I found the same results with my battery bank as well Andy. I have my JK balancer Delta cell voltage set to .005v. I leave my balancer off now except for what I call a "maintenance balance" and try to do this about once every 3 months or so. Meaning I turn on the balancer, do a bulk charge and as the battery hits its peak voltage and shows 100% it then charges for a while longer to complete constant current. Once the bank is truly at 100% and the charging cycle is done (My inverters to an excellent job at this) I turn OFF the balancer and let the bank run - discharging and charging back up again (Day to day operations) and while the delta will obviously change It stays well within a good range. The DCV will actually get better as I the pack reaches full absorption. These tests that you run and your step by step trials that you show on YT are such a help to people trying to understand this technology and they are priceless! They help me as well so that I can be assured that what I "think" I have learned holds true. You are a great asset to the community and I still enjoy watching your vids. Too bad we don't live closer so that we could share an odda.. odeng.. odi.. Well one of your beers! haha Thanks, Dan
Thanks a lot, Dan. Appreciate all your kind words and you many comments. It has been a great support! That is great info for everyone. Do you just turn the balancers on manually or use a switch/relay.
@@OffGridGarageAustralia We all learn from each other eh? We can talk about it but YOU show it, discuss it, learn from it and pass it on. One of the big differences is you involve the viewers for help and I don't know how you find the time.. but you read comments from us viewers to help you out as we ALL go along. That is a great quality. You are a good teacher.
@@danfitzpatrick4112 Yes Dan, I agree, I feel honoured to get reply’s from Andy, he is a real inspiration, it must be a hard slog to keep up to all he does, I can really appreciate three must be a lot of behind the scenes stuff going on with just keeping up to comments alone, and he still answers so many. Anyhow Andy, I think I can say a big Thankyou from all of us here, even those who may have different views on things that go on here, your channel gives/creates food for thought if nothing else for those observers too, & everyone can and does learn from your wonderfully edited videos & experiments. It’s good to see what comes from your testing the system to its extremities which does give us all a better understanding or helps to confirm what we may believe of this great chemistry, & possibly helps to completely change what they have always believed or been told by the uneducated. Often many Solar PV systems may not perform to these extremes, but it is good to know the limits if you want understand or design such systems. Cheers All!
@@LithiumBatteryGuy I'm testing! I don't have any voltage difference either. See the middle battery/BMS, no problem. It's a test! I'm testing things here in the channel and go of the regular path on purpose to see what is going to happen. I need to mention this more often in my videos for new people to the channel 😊
How? This just proves that the pack which didn't have an active balancer attached had no issues. It doesn't prove anything about the quality of the jkbms. Repeat the test with the active balancer on the jkbms and see if the other two packs have a problem. Based on the conclusion the jkbms pack should have the same issue.
Andy, I think you might have a 'runner' (Overkill #16 cell). I have a cell just like that one. Once it reaches 3.4x it starts running away increasing it's voltage until the overcharge protections kicks In. I have tried many things to balance it with the others. But after many failed attempts, I believe it has gone bad. it always behaves the same way. With or without active balancer. It would be interesting to swap it position with other cells and see if the behavior is the same.
I have a similar cell ,it always shuts down the BMS on over voltage every time. I think i shall buy four more cells for backup replacements .. it makes it very difficult to fully charge the battery.
@@davidkettell6236 I charge my cells to 3.4v (27.2v), which is exactly the voltage were the cell starts separating from the other because of the absorption time. This is what I consider 100% Charge. But still I will probably replace it. It should not be doing that.
New cells or second life I seem to always have one that runs up the curve ahead of all the others, if I replace it then the replacement is usually just enough off that another cell now becomes the runner. It seems to just be the nature of it, that's where the minute different in absolute energy storage between cells shows up. That's why I like the JK active balancer, it has made that problem basically disappear. I still datalog the cycles so I know if any cells are becoming burners that the JK is covering up though.
@@captainobvious9188 I have a active balancer connected and it brings down the voltage of that cell faster than the BMS will do. When in "float", it prevents it from running off again, but the voltage always remains above the other cells. In the evening, when the discharge cycle starts, it levels with all other cells and the difference in voltages between cells become 5mv. Is just that peak voltage after hitting just above 3.4v.
Andy, If in future two week period this cell is still an issue you could do a charge test(out of the pack) and see if the cells also runs away after hitting 3.4v.
Thanks for putting this data out Andy. I have been running 2 strings of 280ah and 2 strings of 100ah for several months now, with no active balancers and my difference is between 1-3 millivolts across the 64 cells.
Batrium is known for relatively high current passive balancing, at least that's so in my older lithium ion setup. Batrium works for lithium iron too? No reason it shouldn't.
Yes, the Batrium can discharge with 1.3A and is very effective (not efficient) at higher voltages. It also matters how often your cells hit the higher voltages. Do it daily and the drift will be very small, do it once every 2 months, deviation is much higher.
You already proved this concept months ago but it's nice to see it proved out in actual real world off grid conditions. Nice. I wish Victron would make us a 16S fully programmable BMS. Another blue box opportunity , they surely will soon .
Some said, it was because of the 'old' battery and bad connections between bus bars and terminals. I wanted to see if they were right 😉 Yeah, the Victron BMS would be great. I don't know why they don't. Probably want to sell their own smart batteries.
Another great comparison. Looking forward to see how the next 2 week test turns out. I bet the JK BMS sellers are getting an increase in sales due to you.
Andy - I have been testing 5 balances on my 4S RV battery using cells like your - the 120a blue tooth BMS bleed balances such a low rate they are nearly 0.15v out at top it would probably take a month to balance! 1/The first balance was 0.5a surface mounted multi resistor that never switched on till 3.64v and latched till 3.60v - too high for regular charging and clunky - it also got quite hot 2/The second was 1amp bleed balance that again triggered at 3.6 which was thought to high for regular charging. 3/ The next was active 2amp balance switch mode balance with wire wound inductors - it worked but seemed to have quite high running loads of over 100ma 4/ A 1.5 surface mounted active cell balance that seemed to be very slow though did have twinkly lights - probably suited for smaller cells on e bikes 5/ An 5A active cell balance that uses small metal capacitors like yours - This was the most successful of all 5 and you could see it doing its thing nicely on the phone app - it worked in parallel with the BMS and brought the cells together nicely over night - it goes in to sleep mode at 3V - I wish it would be adjustable so sleep at 3.3v - it seems to have very low running loads Just thought you might be interested
Fantastic testing, Trev. That is great information. I also have some other balancers but they are all crap and not really working with LFP. They may come from Li-ion setups and could work there far better. Thanks a lot for sharing.
Thanks again for all the hard work! I took the plunge and ordered 32 280Ah K cells from Amy, 2 JK's from alib. Still getting the rest to get started. Will use a Victron now and will get another one when I go to multiple fases. You have convinced me to go, there is no hard reason yet here in the Netherlands, but I expect this in the near future, the electeonics and cells are now hard to get and prices are still rising.
Woohoo, Edward. That's a huge setup with 28kWh of storage. It will be great! Yeah energy prices won't come down for a long time any more, so that was the right decision. The JKs will work perfectly work the EVE cells. Do you get a discount from Victron when you buy directly from them, factory direct? 😂
So, the Helltec balancers often have a run or enable solder bridge. It should be possible to use one of these generic voltage controllers with a relay to activate the balancer when the pack voltage is high enough to start balancing. In my case, I monitor my battery bank with a raspberry and will soon implement the switching (of the balancer) on cell voltage level with a logic in the raspberry. Then it would work like the JK BMS. Edit: well, you just had the same idea. Still might be interesting for someone without victron charge controllers.
I have done something similar and it worked great. Last week I replaced the raspberry with an esp32 which connects to the uart port of my daly bms directly. The esp32 uses esphome which now has a module for daly bms. It monitors bms parameters and triggers the balancer via a relay when the difference is over 0.02v and the cell voltage is above 3.38v
I have given up worrying about if the BMS or the active cell balances are balancing the cells correctly, I now every three months charge the cells individually with a 3.5 V power supply and once its output drops to 800 milliamps I move onto the next cell I do this with all the cells still connected in series and have no More problems with cell imbalances. Is this the right way to go I don’t know but it works for me. Food for thought with your setup is that maybe the two battery banks that you are having imbalance problems are supplying more of the load and thus cycling more then the battery with just the BMS on it. I have seen this before with parallel banks of batteries for some reason one battery does not discharge as quickly as the other batteries but instead takes charge from the other batteries. It would be interesting to put a shunt meter on each of the battery banks to see what current they have supplied. Love your work.
Thanks Phil. Yep, I have done the same in the past and used a power supply. It can just take a long time doing that. With the JK-BMS, this is now something from the past... I also don't have any balancing problems as you said. These two battery banks were connected to an active balancer for two weeks which caused the imbalance. I can see the individual currents of each battery bank through the BMS. I have never seen any equalisation currents from one bank into another. One bank can take significant less current than another one while charging or supply more current than others while discharging though. Current from one bank to another occurs only when I had one bank turned of at the breaker to work on it for some time and re-introduce it. There could be currents from 20-80A for a short moment but nothing dramatic. I always make sure the voltages are not too different before re-connecting.
Once that eyebrow hair gets a little longer and connects to the back of your head you can clamp an ammeter around it and measure the current to see the deviation between that and the top balancer current. Staying connected and being one with your batteries is of the most importance. 🤣 No seriously, just a little humor, I do love all that your do for everyone with the batteries and the long hours you put into all this testing. Keep it up. 😁
Good to see a test of what we had already summised. Maybe a workaround would be a relay that is enabled by cc or someother device to enable the active balancers.. or a jk BMS...
Another great vid Andy! Everything about the JK seems pretty damn good, I have one on order since watching ur stuff here like many others. Thanks for all ur great info!
Andy nice test...., go on. Nach einem Jahr auf deinem Kanal, ich gebe es wirklich interessierten Bekannten weiter und gebe Ihnen nur deinen Channel. Sie sind auch sehr Begeistert wie Du das machst. Weiter so, mein Multi läuft, leider will die Sonne nicht so, in Norddeutschland, aber das wird schon :D, ein Bier für deine Heimat, *Prost* .
Danke Dir vielmals, toller Support! Das gleiche hier unten keine Sonne, stattdessen eine zweite Flut 🤦♂️. Internet weg, Power weg... Power kann ich ersetzen, Internet nicht so...
@@OffGridGarageAustralia Verdammt und bei mir in Norddeutschland dürre, wir würden uns über regen freuen. Kopf hoch und vor allem immer über dem Wasser ( Pool ausgenommen) , hoffe das lässt bald nach und das keine gravierenden Schäden an Personen und Haus entstanden sind.
Good sets of videos but if you really want to see if the issue is the active balancer, you need to move the BMS and active balancer to different battery banks. It could be really just an issue with cells or the BMS differences.
I have 2 batteries. Both jk bms. I've done similar testing as you. I just leave the balancer on at 3.4v charge to 3.5v as a normal. I found an unbalanced pack (discharge,charge) with the balancer off then at the top turn on the balancer eventually top balances the pack again. I did this to 9mv deviation then tested 8 cells individually. All discharged full capacity. Life is easy Andy so leave the balancer on. Great testing and video. From So Cal usa. How goes the 1.21gw used solar panels? BTW I've noticed cell swelling over 3.4v if I charge above .2C. Charge at .1C no swelling.
The jk bms is fantastic, my 400ah 16s battery was around 50% state of charge for almost 3 months before i was able to get a full charge, but when i did, it was able to balance the cells perfectly. The only problem i noticed is the bms shows the incorrect voltage and the current is slightly wrong too, meaning that the % remaining display was wrong too. This can be easily calibrated in the jk bms settings and it looks like yours has the same error, im not sure if youve noticed but Andy, your jk bms shows almost 1v higher than the other bms and your set charge voltage, and the battery percentage shows 94% even though we know that it is now fully charged. I also discovered that this inaccurate display does affect the bms turning off discharge at the low cell voltage.
Thanks Lexi. I'm not too fused about the numbers the BMS shows. My point of truth is still the Victron Smart Shunt. The shunt also reports V and A to the charge controllers and inverter. I have 4 devices measuring SOC and voltage, they are all different, so I had to pick one 😏
@@OffGridGarageAustralia yeah Andy, I have found the same problem with thermometers, none are ever the same, you gotta just pick one u reckon is closest.
After the next charge cycle in a few weeks, if still all over the place in voltage differences, maybe swap the JK bms with either top or bottom bank, maybe the top, so you don't have to bend awkwardly, then if cell 16 is still weird on JK, you know it's not a BMS issue.
I doubt it's actually a problem with cell #16 because both battery banks (top and bottom) have the same behaviour but have different battery types (304Ah to 280Ah). I bet it is how the balancer works. Cell 13, 14 and 15 are high as well when leaving the balancer connected.
What if the bms without active balancer is really that good? Would consider shuffling the bms's between batteries? Or doing it the other way,, put a active balancer on that middle bms?
If you need to have a balancer connected all the time, it must be one of these two types (imho). Either a DC/DC to the lowest cell charge pump, or a double charger solution. The first balancer type grabs some current from a charger (a charger keeps a current constant, and so if some current go to the DC/DC, then less current remains for all cells), and sends this energy to a cell with the lowest voltage. No discharging happens. No unwilling disbalance. And the second balancer type uses two chargers, and bypasses the most charged cell, so it appears disconnected for some time, until other cells will have a same voltage. Again, no discharging happens. All the other balancer types which assume a discharging, are intended to be used only at a final phase, when a charging is completed. Oh.. And there is the third type: a DC/AC to a multi-coil transformer. It also takes an energy from all cells/charger and feeds all slowing cells at once. Check out Sunkko balancer. Despite it uses only one phase in DC/AC as I suppose, it gives an idea. May be you could test it with your battery. I'm not sure in this case, because this type of balancers changes a charging current for multiple cells at once. PS In another words, if a balancer keeps a same charging current for all cells except a most outstanding, I think this is fine to have it active all the time. To slow down the most charged cell is always better than to push up the weakest. This is interesting that a passive balancer makes the same ) And considering this, I'd suggest that the double charger solution is the best from many perspectives. But no existing controllers use it afaik
Hi Andy This might be a little off topic. But can't you use a normal grid tie converter to connect to your off line garage to strengthen your 240v supply. I have wondered about that because you are totally off grid in your garage, so your 240v system in the garage acts like the grid.
This can only be done with a Victron Multiplus which can take the energy from another inverter in the micro grid and also turn it off. Imaging the following: your batteries are full, not many loads connected and the grid tie inverter tries to export all its energy to the grid. That's what it is supposed to do. This would end in a big bang. So the trick is to control the grid inverter somehow and tell it to throttle down and even stop delivering power. This is exactly what the Victron Multiplus can do with a feature called frequency shifting. I will do this in the near future...
Andy, off topic sorry, but to be clear, you can use ur Tesla as a storage battery that you can charge AND discharge from, cant you, or would you need to make certain mods to discharge from a Tesla as a backup power supply for whatever reason? I like what ur doing here, & I have been considering some of the extra benefits of owning an EV, extra storage, redundancy & a car that could do a few hundred kms, would be a good 2nd runabout & reason(able excuse! Maybe!), to do something like ur. Even if I dont, love ur stuff! Thanks
This needs a special installation and home 'charger' which transfers power in two ways and also turns off the grid if the car supplies power. Tesla does not do that at the moment for several reasons. One of them is free Supercharging. You know what people would do...
Hi Andy, I am a bitt perplex with your last video. "Permanent balancing is counterproductive".... ok ... and you shown than during two weeks without any balancing, you have better results that with... If I extrapole a bit, it means almost after a super top balancing, you can eventually run everything without balancer. I guess the fact behind the scene is you have some Great LFPO cells .... very good quality. IMHO, the interest of an earlier balancing can come if you have some inohomegeous cells. For example whatever the starting balance voltage I am setting (3.45 ), my cells little by little becomre more and more unbalanced .... :( with my JKBMS...
It's not that easy unfortunately. If you need balancing or not depends solely on your cells but moreover on your setup. If you can recharge your cells every day the drift will be small, even they are B or C-grade cells. So the balancer of the BMS may be sufficient to counter that and keep the pack in balance. But we now see many people getting more and more storage with larger installations and it is likely that we don't fully charge for weeks if not months. In these cases, balancing needs some help...
Hi Andy, if we have two similar LFP battery banks one with Active while second is only passive balancer. In general will the first one (with Active balancing) a) consume lesser energy to charge if both SOCs were same. b) with same SOC level, will the charge time faster for active type.
How bad is a 100-millivolt difference? (i don't know) Since my plan is to run at 3.35 the active balancer would not be working as a top balancer. A scheduled once-a-month top balance at 3.6 is a possible plan for my batteries. A good video except for the BMS on the right seems like it needs to be replaced or updated or something, as you know. My older recycled battery bank may need more active balancing than a fresh bank. Where I live its almost always very sunny and rarely rains so it's interesting to see a bank not get charged up easily. Keep up the good work Andy.
Thanks Ron, the Heltec BMS on the right is not great. It is installed for testing purposes but I think I'm done now with it 😆 Absolutely agreed with your monthly maintenance using a balancer. That would be ideal. 100mV deviation is certainly not a problem as long as all cells are in the steeper area of the curve. Highest cell at 3.6V and lowest at 3.5 is perfectly fine, they will have the same capacity at this stage.
Another awesome video mate 👍👍 I was just looking into ordering active balancers and JBD bms's. New conclusion is scrap the balancers and instead order JK BMS's only?? Thanks in advance mate!!
@@OffGridGarageAustralia literally in the process of ordering. Need JK 4-8s, 17s and 24s variants for different applications. Would you recommend any supplier in particular?
@@oneman29 have a look on my website, there are links to all the BMSes you want. There is also a $10 coupon code you can use at checkout. off-grid-garage.com/battery-management-systems-bms/
@@OffGridGarageAustralia I just got the chance to rewatch the premiere and realised you mentioned it right at the beginning, which wasn't works for me when aired. But thanks again for videos and responses mate! Awesome stuff 👍👍
I don't quite understand your issues with the active balancers being connected all the time. Ok, my battery system is a lot smaller than yours, I only have 4 cells. But I never see an imbalance of 100mV, typically all cells are spot on the same, maybe 10mV difference sometime. I trust the balancer that much, that I meanwhile disconnected the BMS. Voltage protection of inverter and charger is enough and it takes out an additional point of failure as well as less resistance (heat losses) in the system. Could it be that your BMS and your balancers somehow work against each other? Grüße aus dem Nord-Schwarzwald (es regnet schon wieder).
Andy, i noticed both the Heltec and Overkill have cell #16 very high. This cannot be a coincidence?!? I have a 2P16S 2x280Ah setup with a Daly (bought it B4 I saw your great video's which are so helpful to me now) and also in my case the cell towards the end is always higher. What's your view on that?
That is caused by the active balancer for some reason. Others have had the same issue when having this balancer connected all the time. For some reason, it slightly prefers to charge cell #16 more than others if it has enough time. Could be part of the balancer algorithm they are using.
Hey Andy, What if you turn the balancing feature off on your OverKill BMS and keep the Active Balancer continuously connected? So only the Active Balancer will perform balancing function. That will in essence be what the JK-BMS is...No?
Thanks Eban. The essential difference her eis WHEN you turn on the active balancer. The JK BMS has a balance start voltage when it activates the balancer while the active balancer will balance all the time. And exactly that is the problem. You don't want it to balance all the time.
Hi Andy, I've been using JK BMS on my 8s pack and it works great. I am curious, what is "Cycle capacity" and looks like it is changing over the time. Can you please clarify? Thank you, appreciate your channel and all you do.
Thanks Oleg. Cycle capacity is what the BMS observes you cycle the battery with. So this is basically what you real capacity you use over time from your max capacity of the pack.
I have enjoyed watching your channel and your progression since you received your first 16 cells. I have been about a month behind you in testing, playing with, building batteries. But I also now sell them. I have a few comments about your balancing issues. First I don’t trust active balancers enough to leave them connected. Unnecessary tech in my view. I have been testing one for weeks. I intentionally put a 12v 230ah pack together with one cell fully charged and the other 3 almost discharged. I connected the active balancer and it moved some power around until the high cell went below 3.38 then it would stop. But the light stayed on. Since the stop happened twice I connected a power supply to the high cell. Set the output at 3.6v and 800 watts. It has been connected like that for a few weeks and the 3 low cells are slowly charging (judged by voltage) and the high cell sits at 3.56v. So the active balancer is definitely taking the 800 watts and moving it to the other cells. So configured like this I guess you could top balance your battery with this Method. But why would you? In 1/10 the time I can put the pack in parallel and top balance it in a day. So I can’t get my head around why I need one. My other comment surrounds cell balancing. I have come to believe that we place too much emphasis on exact balance between the cells. In my view as long as when the highest cell hit 3.55v (my max cell v setting) all the other cells are in that steep area of the charge then why care if they are 100 mv out of balance? As long as all are over 3.4 before that shut off happens you are dealing with under 1% capacity loss due to imbalance. If 2.8 amp hours means that much to you, you need a bigger battery. I have watched batteries that seem to be perfectly balanced for a year. Never more than 30mv out of balance even at 3.5v. I have seen others that would have a cell at 3.45 and another hit 3.55 and the BMS stops charging. Their capacity was almost identical to the first test done on it when it was perfectly balanced. So my question would be: if the pack capacity is not changed remarkably when the cells are 100 or 120 mv out of balance at the top of the charge, who cares? I would not be concerned unless I saw a reduction in capacity. If I saw that, or saw a 200mv delta when one cell is at 3.55 I would take the battery out of service for a day, remove the bus bars and connect it in parallel
Hit send just a bit too soon! I meant to finish with connect in parallel and top balance it with a 3.6v power supply. Put it back together and see if it happens again. If I had to do that to a battery every 6 months or a year it would not bother me much. Fun watching your channel, keep it up! Although I have trouble believing you need more capacity than you have now! There is a huge amount of energy in the off grid garage. Well done. I’ll keep watching.
Thanks for sharing your thoughts, David (you can also edit your own comments after you have sent them😉). The method to top balance your battery with an active balancer makes sense if your pack is already built and it would be a tremendous effort to take it all apart again and connect the cells in parallel. You can also keep using the battery system while doing this top balancing, so nothing needs to be turned off if the power source is strong enough to power your loads. But yes, I agree for a new battery, it is faster to parallel them first to balance them. Yes, I fully agree with you on that argument of balancing if cells are not running away and are all in the steep area of the charging curve ( I made a video about this a while back). The capacity is then already very close together, even voltage differs. So practically no gain when balancing them any further. We have done all this testing here on the channel and charged a cell to different voltages to measure the capacity. Hence I now charge mine only to 3.45V and let them absorb for a while until they all catch up and are saturated. I certainly don't need all this capacity right now. It basically matches the capacity in the Tesla battery already. This is mor for learning and testing purposes. There are more batteries coming in the future though. Not that I need them but... Thanks again for sharing, great comment.
@@davidwhite47 great comment David, keep watching Andy’s vids, he has got a few to get thru, I haven’t seen em all yet but probly getting there soon. I have made comments & then watched another vid & thought, okay well that answers that, I can see where he is going to some degree here, Andy has a 45kwh Tesla I think, so 44kwh battery is probly a good project area, for ‘Andy’ to start with anyhow. We all made a lot of comments about how to hook it all up to his house, but there were actually a number of complex issues & concerns for Andy regarding that matter, & I believe he went down the right path regardless of everyone’s comments, & he didn’t want to mess with his already installed system & FIT, fair & prudent call. You obviously know what ur doing David, & Andy is a pretty good listener too IMO, I like going thru many of the varied comments here, I learn a lot, and I think so many others do too. Some of these experiments & tests help us understand for when sh*t happens (when ur away for awhile), and ways we can combat these potential problems that may well never happen to many of us. Didn’t mean to bore u with a lengthy comment, & nothing wrong with urs, it was well placed, but I do love this channel, & I think Andy’s logic seems overall pretty sound, & he doesn’t mind saying if he thinks he has f**ked up either, & he does ‘fiddle’ with things pretty hard, so I think he’s doing at least 4 Frogs as he puts it, “Humble is the Wise man”, Cheers!
Andy is THE balance king. But sometimes I wonder if the capacity % gain/loss is all that important also. If they’re coming back together at the top knee you have to be pretty close to real good. Gotta love that over the top spat man.
Oh man.... Hut ab... Also ich hätte ja viel gedacht aber das hätte ich nicht erwartet.. Mir war klar das die Balancer dann nur noch so wenig leisten.. Ich fahre die Akkus von etwa 5 bis 90 Prozent.. Also kurz vor der steilen kurve... Somit ist mir das noch nie aufgefallen... Ich glaub ich hab viel Arbeit am Wochenende 🙈
I use a simple over/under voltage relay and use it to turn my active balancer on when the bank voltage goes above 27.2 volts and then turn off when it drops below 27.1 volts (for my 24V battery). The relay I use can also turn on at the low end of the voltage range if I want it to bottom balance, but I have not enabled the undervoltage setting on the relay. Seems to work pretty well and its cheap and simple.
When the battery is charging from mppt charge controller and the bms disconnects the battery due to high cell voltage or temp etc does it damage the charge controller if it is seeing full pv power and the bms isn't connected via a communications cable?
Hello Andy. Another amazing video! I just received 2 active balancer for my futur 32 cells batteries sets JKBMS controlled. Should I sell them or any interest to keep active balancer when I see your results?
Hello Andy, The heltec can be good especially if the solar system is connected to the grid. For example I use a seplos bms and it will fully charge the battery and then disconnect the charging so that the exces solar power can be fed in the grid but if a cloud is passing there Wil be a short voltage dip and some power will be used from the battery and if the cloud is gone the voltage Wil rise and charge the battery again this will result in a lot of rapid charge and discharges is one day. For example the seplos Wil stop charging at 100% and only enabled it under 90% to keep this rapid cycles at a minimum
Hello Rutger, thanks for your comment. I find this fascinating that you use a BMS to terminate charging! Should this not be the role of the solar charge controller? A BMS is for protection only, not regulate the charging state of the battery.
@@OffGridGarageAustralia yes if the system is off grid I would agree. But if the system is on grid it's not possible if you turn of the mppt you will also not be able to feed back in to the grid. For now this is the only solution I found not to fast cycle the batteries at high state of charge. Before with the other setup the batteries got pretty warm on a cloudy day and the state of charge was going up and down from 96 to 100% Now it's yust going to 100% and only drops to 96 on a cloudy day but no rapid charges in between
@@Rutgeroppenhuizen The BMS should not disconnect charging unless there is an OV, UV, OC or OT situation! The battery will take less power once it gets full which the solar charge controllers keep sending energy. What the battery won't take, goes into the grid. Once the battery is fully charged all solar power goes into the grid and the battery floats. There is no cycling of the battery at 100%. If they get warm or you have watched them cycling between 96 and 100% there is something fundamentally wrong. Could bad faulty hardware, wrong settings or bad system design.
As mentioned the last time I have the opposite experience. Frankly, I do not charge or discharge my 250Ah with more than 30A so the 2 parallel 5A active balancers have enough time to catch up with any potential deviation. I will leave em connected all the time.
How is it with yours, if you hit like 40 amps of charge? I quite soon get cell voltage limit on my dalybms cause my 1A active balancer seems not to be able to catch up. Then it falls quite fast (minute) back to 3.25 as the rest is and the game starts over.. (16s, 200ah, calb lifepo4) Is that normal?
Very overrated in my opinion. For what reason do you want this? If the battery gets low, the inverter will shut down any way. If the battery gets high, the solar charge controller will stop charging. All this happens without communication. I really don't see a benefit from having this communication. It just ads more to the complexity of the whole system... I left a comment on Jens' channel.
Andy, on those active balancers, the pad that is soldered with "RUN" label, you can unsolder that connection and insert a relay connection controlled by something else like your raspberry pi, triggered at a specific voltage or set of parameters. Or... you could build a simple divider circuit with a relay, so it would closed loop turn on at the top of the charge only.
Andy I'm in need of your professional advice in a bad Way!!! I have 24 nissan leaf modules in a 24 volt configuration. I need advice on a bms. I am running them without a bms and people say it's dangerous. I'd rather not burn down my camper so I'm trying to find a good, easy to understand and set up bms. The leaf cells have a weird top voltage of like 25 volts and I take them down to 20 volts. Do you know of any good quality bms that can be adjusted to those voltages? I've never had a bms before so it's all new to me. Any help is greatly appreciated
@@OffGridGarageAustralia this will sound confusing but here goes. Each module is 2s2p. I have 12 modules per stack. Each stack of 12 is 4 modules in a group and each group in a series of 3. Then there are the 2 stacks at 24 volts in parallel. So it's 2s2p4p3s2p
I could do a 6s bms if I could find one that supported a 4.2 nominal voltage per cell. I need 2 bms that are 6 s but yes it would have to have a high voltage of 25 volts and all bms I see are for lifepo4 and have much higher voltage for a 24 volt pack
I don't have solar panels or big battery banks, but I had to discover battery balancers myself about a month ago after I got annoyed that Lead-Acid batteries in 24V cheap consumer UPS die so often... You can put high quality 8-10 years lifetime batteries in it, and after 1-3 years one battery will almost always fail... Of course, these UPS never have any balancing in them… So, now I've added a simple 2S active balancer to my UPS... It didn't solve the problem entirely because it turns out that one of the batteries is half-dead anyway, and the balancer can't bring its voltage to the same level no matter what... And the capacity is roughly 50-60% of what it should be... So, next week I'll install fresh batteries, with a balancer, and I hope they'll last longer this time...
In my situation, I bought some pre made batteries (3x 130ah lifepo4) which run a jbd bms. I have found the cells don’t balance at the top or bottom well. I am getting 330ah from a supposed 390ah total. So I have bought an active balancer to help get both the top and bottom ah out of the pack. I keep seeing people test these active balancers with one cell fully charged and the others depleted which is not what these active balancers are designed to solve for.
Andy, if in two weeks time (or so), your theory is proven correct, that active balancing in the flat part of the curve is contraindicated, maybe show us how to automate. Can a simple relay be utilized to somehow switch on the active balancers if voltage reaches a certain threshold?
I saw on the forum a low voltage disconnect board setup so the active balancer would stop below some voltage e.g. start above some voltage and thus "helping" the BMS. But, would this also be an option for bottom balancing for periods where the lack of sun doesn't give us a full charge?
Andy, the active balancers are too small for your battery size. You can parallel them. So try putting the two 5A ones together on one battery. I just bought the heltec 10a one for my 8s 24v batteries. It will make a difference as the amperes used at 0.1v difference will be 1.2A x 2 = 2.4A - which is equivalent to your JK BMS.
Yes, you can parallel them. But this would also introduce even more complexity to the system. Once the balancer is running only at the top of the charging curve, it will be fine. I also have a 10A active balancer here. But it's only for a 4s battery.
@@OffGridGarageAustralia i would love to see the 10a one being used 😃 especially as mine are arriving shortly. Also, would appreciate some ideas on how to safely modify a pre built battery that has been spot welded. Is it best to solder the balance wires on? Or something else?
Hello, I am a scientist at a German university and I am investigating LFP cells with a special test rig. Unfortunately I can't give more details, but I can explain where the problems with the active balancers come from. From my own tests I know how precise the active balancers are. If you supply the balancers with a power supply at the highest and lowest potential, you get partial voltages that are accurate to the mV. And exactly here is the problem, the voltages at the cells are dependent on several factors, such as temperature and the slightly different internal resistances (when they are charged and discharged). So the cell voltages are not absolutely the same in operation even with the same SoC. Nevertheless, the balancer tries to equalize the cell voltages. I would therefore recommend using the active balancers only for top and bottom balancing.
Indeed - but if you look at the specs of this specific active balancer (Heltec 5.5A) you will see that the balancing will occur in a gradual way from 0.01 to 0.1v differences, with the 0.1v difference being 1.5A for 8S. As we all know, the LFP voltage curves are flat in the middle, so the balancer will actually put itself to sleep until it sees a higher difference. Also as we all know, LFP voltage curves happen at the bottom and the top of the pack. So in essence, under normal operation in say a house battery, these balancers will top and bottom balance your system. Also, the manufacturer states that
Thanks for your comment and support of my theory. We have made such a test a few months ago already where I found the same result. The balancer was permanently connected to a 16s battery and basically caused an imbalance over time which it could not re-balance once fully charged. Some viewers said this could have been caused by the fact the my terminal to busbar connections were not optimal (higher and different resistance) and therefore the balancer balanced out the voltage difference it saw. This test here was to demonstrate that the problem is not caused by the bus bar connections but more likely by the variation of the cells as you described them. In the next test, we will see how different the cells will perform when fully charged again without the balancer.
@@OffGridGarageAustralia Of course, it is always an interaction of various influences. The contact resistances of the busbars can also contribute to this. However, this should not be overestimated. There is also a thermal influence that should not be neglected. If a cell heats up more, its internal resistance drops somewhat and thus its voltage. At the busbars and the cells in the middle of the set, the heat is evenly distributed. At the edge cells with the transition to the wires, it may be that additional heat is introduced from the wires. Therefore, the voltage at outer cells can be lower, which leads to a continuous recharging of the active balancer to this cell. Regarding the answer of Micheal Wood, I could not confirm in my tests that the active balancers go into a sleep mode when the cell voltage is approximately the same. I can confirm that they have a lower turn-on threshold as stated by the manufacturer. However, only the first cell is considered for this. As I said before, my recommendation is to use the balancers only close to the charge and discharge end. This can be programmed e.g. with a Raspberry PI or also the Cerbo GX (e.g. Node-Red). There is an "Enable" solder bridge on the balancer boards, which you can lead with wires to a control relay for example. I'm building something like this right now with my PV storage. It just use an additional cell voltage measurements and control the Multiplus inverters according to their charge status.
I found this video by searching for my issue being similar. I have a cell in my 4S system that always reaches the final voltage before all others but also reaches the lowest voltage before all others when under load. The supplier recommended adding an active balancer, which I have on 24/7 - after 5 months of testing, the same cell still reaches high voltage before all others AND still reaches lowest voltage before all others. To me, this looks like this one cell has a lower capacity than the others maybe because of degradation. This pack had only 13 full cycles since put together. Should I try to disconnect the balancer when discharging and only have it connected when charging above 3.45 V or do you have other suggestions?
Hallo Andy! Mich würden deine (dauerhaften) Einstellungen für das JK BMS interessieren. Insbesondere Bulk/Float Voltage (Ladespannung WR), OverVolt und UnderVolt Protection im BMS. Gehst du mit deinen Werten 20-80% oder 10-100% ? Ganz liebe Grüße aus Deutschland
Danke Dir Christian. Mit LioFePO4 kann man getrost bis 100% laden und die Energie auch nutzen. Ganz entladen tue ich den Akku jedoch auch nicht, ausser ich teste etwas. Mit der grossen Batterie nun, komme ich sehr selten in den Bereich von 3.0V oder darunter. Im uebernachsten Video stelle ich das JK-BMS 4s vor und da gehe ich genau auf alle Einstellungen ein.
@@OffGridGarageAustralia Danke, da freue ich mich dann besonders auf das übernächste Video. Bleib am Ball und halte uns up to Date. Ich schau aber alle deine Videos gern. (auf den anderen Kanälen auch!)
Hi Andy, greetings from Finland, we have here a storm and 6 degrees below zero and no frogs... Have you measured the voltage loss of the bush bars with a high load current? That would be a very easy way to check for a good contact. Just measure the voltage from the tip of the battery bolts between the bars. Br, Eeli
Ive noticed you have the Breaker for each bank AFTER the BMS. I was considering a breaker before the BMS (multi bank solution, similar to Andy's). Pro and Cons? I just think a breaker before BMS will protect bank if BMS has a meltdown.
That was part of my design, regardless what will happens, the BMS will still be connected to the battery. In case of an emergency shutdown I still have the BMS to give me all kind of information. Also for maintenance, I flick the breaker and can work on the battery including the BMS. I can let the BMS balance this one pack over night for example. I think battery and BMS is one unit and should not be separated. Either is useless without the other.
@@OffGridGarageAustralia makes sense. I also realised your breakers are double pole when i was drawing my diagram and realised it’s actually protected on either side
@@OffGridGarageAustralia Yes they do but they are set up as the only form of protection. Its easy to lose some capacity when the bms is conservative, the battery monitor cutoff set above that then the inverter above that again. Homebrew batteries are the way to go.
No, I was in contact with them but felt, this is not the right BMS for my setup. I wanted several independent batteries which are not reliant on just one BMS. With my setup now, I can just turn one bank off completely without affecting the other two. I doubt this would be the case with the Batrium.
I did see that issue with the same type of balancer on my bank (a 48v 150ah). back when I had a 8x 250ah AGM´s, to help balance the voltage throughout the two banks (4 each) I would connect the batteries between the two banks. this means that both banks were in parallel on all batteries, not just the end units positive and negative. I imagine you´ll be able to do it on lithium as well. Just a thought that might help when you got multiple banks...
Its totally doable to parrellel all cells, balance also seems to improve because of it. Its a lot of extra connections and much more difficult when you have to troubleshoot to find a failing cell.
So, if the active balancer should not be connected all the time, how would you turn it off on the SunKit battery once you close up the case? Can you turn it off remotely?
That is a very good question, Ricky. I would like to have either a physical switch on the outside of the box or a relay which turn on at a certain voltage. These balancers don't Bluetooth so no remote option there.
What do I think? I think this video raises a lot of questions. First of all, how much cell deviation is allowable? 1mV, 5mV, 50mV, 100mV. Depends who you ask I guess. Do any of these active balancer come with blue tooth so you can chance the parameters like you do with the BMS. If so you could then disable balancing below a certain cell voltage. How long before BMS's come with inbuilt active balancers. Also this video suggests that a BMS is not really needed once everything is set up correctly. Once the battery is balanced, so long as it is never fully discharged it should be fine. After all the BMS should not be there to stop the battery charging. The charge controller should do that. Maybe not in your case with multiple batteries, but in the case of a single battery.
All 3x BMS’s had BlueTooth, which is how Andy got the displays. Each is programmable, in their own way. The value of the BMS is to keep a lithium fire from occurring, keep venting from occurring for more stable chemistries, and to otherwise keep from destroying the batteries. I have been struggling with the question of using a more volatile chemistry, never charge it to 100%, then do I really need a BMS, or is a balance board all that is required if the inverter shuts off when the pack is too low? (EGO batteries run like this, and I am generally pleased with the results.) My only concern is possibly killing the welded packs when the weakest cell fails when it will eventually drop too low. This known eventuality keeps pushing me back to using a BMS. I just bought a pair of welded packs that have no BMS, so I am now about to make that decision.
Thanks Peter, that's all good questions raised. I think as long as all cells stay within the specs, balancing is not really necessary unless you see a drop in capacity. The JK-BMS I'm using has already an active balancer and it works flawlessly. You must have misunderstood, a BMS is always needed as I said many time in my videos. It's a must have for your battery. And, as I said many times in my videos and in this one as well, a BMS is not there to control charging. But the Heltec BMS does exactly that and I said, it is wrong.
On the Active balancers, Beware if you try to unsolder the RUN pads, to connect switch or relay. Also only use small gauge wire like 22. I soldered on 1mm wire, but one of the pads came off! There is a very small through hole plated connection. I repaired it by scraping the other side of the board, and soldering a thin wire there. Am using a 24v relay, controlled by XY-CD60L - LCD screen, programmable voltage relay module, in OUT mode. It is about 0.1v reading higher than the true battery voltage. Turns on at 26.8, off at 26.7. Sometimes, when the voltage is falling, it turns on and off, briefly. There are also some timer modes, I have not investigated. Middle SET button clears the flashing display when it turns off. DOWN button is also a manual ON & OFF override, doesn’t always work, so maybe subject to the voltage settings. Holding the SET button allows changing parameters. Pressing SET cycles through displaying the settings.
Hi, I need to setup my batteries in smart shunt 500a and I dont know what is the best voltage for synchronize SOC, by float or by absortion voltage? Thanks for you very good vídeos.
Great question, I will soon go through all the devices I have setup and explain the settings of each. I have set 55.2V as absorption in my solar charge controller and have the smart shunt set to: 55.1V charged voltage 10min detection time 0.5% tail current All three parameters need to be true to reset the shunt to 100%. You may need to adjust the settings a bit to your needs depending on your setup.
Why is always cell number 16 totally out of balance? It's the same case with my 16s pack. After having had the active balancer 24/7 connected, cell 16 hits 3.65v way faster than any other cells/ shows the highest SOC. 0.2v cell difference. I use the same active balancer.
That is something I observed as well! I also found cell 15, 14 and 13 are higher than the others as well. It must be how the balancer works. I've never seen this when I connect it only at higher voltage, only if left connected 24/7.
Andy swap the cells that are overcharging and swap the BMS after that. I am 100 percent sure the problem will follow the cell and it has nothing to do with the BMS or Active Balancer. Also measure the internal resistance of those overcharging cells. I am sure it is different. I am guessing if you check the capacity of cell 3 and 16 individually. You will find it is slightly less than rest of the pack. Balancing is not the issue here. Balancer cannot fix capacity issues
These are not the cells. If you read the comments here, quite a few people have the same issue having a balancer connected 24/7. Also, two different battery banks, two different BMSs, same result... And it seems to affect #16 every time for some reason... Even if they have different capacities, it should not matter once they are top balanced.
@@OffGridGarageAustralia Care to see if the third active balancer on bank2 put it at imbalance. Just remember these balancers will have no chance balancing in real time at high amp charging rate It will balance overnight. Make sure to turn off the solar charge controller overnight. take the reading in the morning than turn the charge controller on. I know on my Dali BMS it was 200 or 300mv deviation before it started balancing the cells. I am not sure what it is for Active balancers. I will also turn off passive balancers on the bms. I do appreciate your work here. Thank you
i discharged my batt at 100a til 2.9v it is a jk bms and mos reached 68 degree c and batt t1, t2 reached 42. batts are in a box. is that temps safe? Where is the unsafe mark?
Hello , you do a great ~ Job thank you I’ve been following you for years ! I have a very good Question for you - in You’re Wisdom I have 2 Lithium Battery Banks 1 - Lithium Phosphate 48v 3.2v 280Ah which I actually have 25 PCS Batteries of the 3.2v & an LTO 2.3v 40Ah & I have actually 24 PCS “ Question - can I use an Active Balancer say for S- 25 wires which the batteries are not connected together but the Balancer will help regenerate the 15 PCS Batteries connected together in series for 48v but the other 11 batteries will help Regenerate the 15 batteries in Series when they drain down and when the Inverter charge controller charges the 15 PCs batteries that’s on the DAILY 15S 120v BMS the Active Balancer will transfer the electrical voltage from the 15 PCs to the other 11 batteries which are not in Series ! You following me ? I’m sure you are with all you’re Experience & Knowledge ! Will this work ? The inverter is an EASUN 5KVA 230v PURE SIN WAVE Inverter Charge Controller 48v GVW ! And another question I want to take the 230v Hybrid Solar Inverter the L1 is Hot 115v & the Neutral is Hot 115v at 5KVA is 98A in only an Emergency electrical lose I want to be able to energize my Breaker Panel I’m in the USA which is 120v @ 100A my Box is a Square D Home Line what I see to Back Feed this Box I Have to Use a 20A Double Pole Breaker and the whole box would be 1 Phase at 115v at 5KVA 98A but my house we use about 3 KW a day - and if it’s a grid down only refrigerators and gas heat with the sump pump would be on I have No 220v in my house so possibly thinking we can run at 1 Phase 115v pure sin wave inverter & do you want a little bit better take a GM 10 SI High Amp Alternator wire 1/0 wire 130A because the Alternator is 120A wire it with 1/0 straight to the Stator the Brass winding under the rear case which produces the Purest Sin Wave 120v spin the alternator with a 12v DC motor speed control the only thing I have not found is a Module or voltage regular yo monitor the battery bank and turn on the 12v DC motor to keep the Battery bank Charged ! My alternators are a GM 10SI high Amp 110A & a Big Block Low Spin GM 10SI 120A & a Ford Mazda 150A Alternator ! And 3 - 12v DC Motors and Charge controllers !
Nice vidéo ! For the heltec, I found is great option if it cut charging at 100°/°. If WE want keep batterie at 80°\° max, WE just have to parameter the capacity if thé batterie at 80°/°. What do you think about that?
Victron should add functionality to the Smart Shunt that allows you to dictate how many amp hours you charge into a battery and then communicate with SCC to stop the charge as opposed to relying on voltage alone. Maybe that way you can actually charge up to 80- 90% reliably.
It depence on the situation i Guess. I have actieve balancer on Every 18S pack (x3). They limit the time it takes to top level by 2 days! The thing to note is that i am running it parralelled on a batrium that is connected with the victron via canbus, the batrium will limit the charging current on the top level and gives the balancers time to top Balance. My cells are used cells... Some of them are allways chargeed faster and discharge faster. I ran it for months without the active balancers and it took for ever to reach top Balance.
Yeah, OK, if you limit the charge current, that's a different situation then. I don't want to do that if the other banks are still able to take energy. We will see in two weeks time.
Do the separate active balancers have an option to only turn on above a certain voltage or else have a way to trigger balancing via a relay? It seems the JKBMS already has this built in.
The separate active balancers being used have no smarts in them. They are completely passive so there is no way for them to control that but as Andy pointed out in a previous video they do have ability to connect to a switch to turn on/off. That is why he mentioned using relays of the charge controllers in a future video to turn them on only after the charge controllers see that they hit 3.45V like the JK BMS already does.
Just a correction Andy: The QLD electricity grid is *always* dominated by fossil fuel energy (coal and gas). In the last 7 days, renewable energy *at its peak* provided 25-30% of grid demand for short periods in the middle of the day, with the rest of supply coming from from coal and gas power plants. Last week renewables contributed 16.2% of the QLD grid demand. QLD grid is *always* very fossil heavy and it's the most carbon intensive grid in the country.
I am sure he meant he is paying the extra from his supplier to be supplied 100% renewable power for his usage. Yes the grid as a whole has a long way to go for fully renewable.
@@jasondevine6014 While I get the idea, physically it's false accounting as it doesn't result in an increase in renewable energy supply. Paying more doesn't make more sun or wind available. All it means is the proportion of fossil fuel consumption allocated to everyone else on the grid is a bit higher. If only 25% of the physical supply is available from renewable sources, then it matters little how much extra you pay for it, there is still only 25% renewable supply available.
The solution is to only allow the active balance when a cell is >3.44v. The external active balancers are not programmable but you can turn them on or off manually.
@@OffGridGarageAustralia Your videos are a hell of a journey.... I know you know what you are doing... I love the demonstrations. It's the best way to teach. You are a great teacher.
Definitely added a JK to my shopping list. Been running the Overkill for a year now. Even without an active balancer things go out of whack way to often. I like the fact you can purchase it with a heater function too. 5his would eliminate the thermal controller I now have stuffed in my battery box. Just a cleaner and more ideal setup all round. With a nicer display to boot.
I found the same results with my battery bank as well Andy.
I have my JK balancer Delta cell voltage set to .005v. I leave my balancer off now except for what I call a "maintenance balance" and try to do this about once every 3 months or so. Meaning I turn on the balancer, do a bulk charge and as the battery hits its peak voltage and shows 100% it then charges for a while longer to complete constant current.
Once the bank is truly at 100% and the charging cycle is done (My inverters to an excellent job at this) I turn OFF the balancer and let the bank run - discharging and charging back up again (Day to day operations) and while the delta will obviously change It stays well within a good range. The DCV will actually get better as I the pack reaches full absorption.
These tests that you run and your step by step trials that you show on YT are such a help to people trying to understand this technology and they are priceless! They help me as well so that I can be assured that what I "think" I have learned holds true.
You are a great asset to the community and I still enjoy watching your vids. Too bad we don't live closer so that we could share an odda.. odeng.. odi.. Well one of your beers! haha
Thanks,
Dan
Thanks a lot, Dan. Appreciate all your kind words and you many comments. It has been a great support!
That is great info for everyone. Do you just turn the balancers on manually or use a switch/relay.
@@OffGridGarageAustralia Manually from the App
@@danfitzpatrick4112 That's convenient and you can do it whenever you feel the cells need some love. Great.
@@OffGridGarageAustralia We all learn from each other eh? We can talk about it but YOU show it, discuss it, learn from it and pass it on. One of the big differences is you involve the viewers for help and I don't know how you find the time.. but you read comments from us viewers to help you out as we ALL go along. That is a great quality. You are a good teacher.
@@danfitzpatrick4112 Yes Dan, I agree, I feel honoured to get reply’s from Andy, he is a real inspiration, it must be a hard slog to keep up to all he does, I can really appreciate three must be a lot of behind the scenes stuff going on with just keeping up to comments alone, and he still answers so many.
Anyhow Andy, I think I can say a big Thankyou from all of us here, even those who may have different views on things that go on here, your channel gives/creates food for thought if nothing else for those observers too, & everyone can and does learn from your wonderfully edited videos & experiments.
It’s good to see what comes from your testing the system to its extremities which does give us all a better understanding or helps to confirm what we may believe of this great chemistry, & possibly helps to completely change what they have always believed or been told by the uneducated. Often many Solar PV systems may not perform to these extremes, but it is good to know the limits if you want understand or design such systems. Cheers All!
This just goes to show that JKBMS is top tier and worth every penny.
Yep, absolutely.
@@LithiumBatteryGuy I'm testing! I don't have any voltage difference either. See the middle battery/BMS, no problem. It's a test! I'm testing things here in the channel and go of the regular path on purpose to see what is going to happen. I need to mention this more often in my videos for new people to the channel 😊
How? This just proves that the pack which didn't have an active balancer attached had no issues. It doesn't prove anything about the quality of the jkbms. Repeat the test with the active balancer on the jkbms and see if the other two packs have a problem. Based on the conclusion the jkbms pack should have the same issue.
@@RowanSmithNZ that's why we do the test without any balancer now to see if these two packs are fine after two weeks.
@@OffGridGarageAustralia can't wait for this test, well the conclusions of! 😁
Andy, you are a genius.
Keep up the good work 😃.
Thank you.
Andy, I think you might have a 'runner' (Overkill #16 cell). I have a cell just like that one. Once it reaches 3.4x it starts running away increasing it's voltage until the overcharge protections kicks In. I have tried many things to balance it with the others. But after many failed attempts, I believe it has gone bad. it always behaves the same way. With or without active balancer. It would be interesting to swap it position with other cells and see if the behavior is the same.
I have a similar cell ,it always shuts down the BMS on over voltage every time. I think i shall buy four more cells for backup replacements .. it makes it very difficult to fully charge the battery.
@@davidkettell6236 I charge my cells to 3.4v (27.2v), which is exactly the voltage were the cell starts separating from the other because of the absorption time. This is what I consider 100% Charge. But still I will probably replace it. It should not be doing that.
New cells or second life I seem to always have one that runs up the curve ahead of all the others, if I replace it then the replacement is usually just enough off that another cell now becomes the runner. It seems to just be the nature of it, that's where the minute different in absolute energy storage between cells shows up. That's why I like the JK active balancer, it has made that problem basically disappear. I still datalog the cycles so I know if any cells are becoming burners that the JK is covering up though.
@@captainobvious9188 I have a active balancer connected and it brings down the voltage of that cell faster than the BMS will do. When in "float", it prevents it from running off again, but the voltage always remains above the other cells. In the evening, when the discharge cycle starts, it levels with all other cells and the difference in voltages between cells become 5mv. Is just that peak voltage after hitting just above 3.4v.
Andy, If in future two week period this cell is still an issue you could do a charge test(out of the pack) and see if the cells also runs away after hitting 3.4v.
Thanks for putting this data out Andy. I have been running 2 strings of 280ah and 2 strings of 100ah for several months now, with no active balancers and my difference is between 1-3 millivolts across the 64 cells.
What BMS are you using?
@@hendersonsobers396 Hello, we are using a Batrium BMS.
@@solargarage Nice
Batrium is known for relatively high current passive balancing, at least that's so in my older lithium ion setup. Batrium works for lithium iron too? No reason it shouldn't.
Yes, the Batrium can discharge with 1.3A and is very effective (not efficient) at higher voltages. It also matters how often your cells hit the higher voltages. Do it daily and the drift will be very small, do it once every 2 months, deviation is much higher.
Andy, you legend! Thanks for all the testing and sharing!
As always thank you Sirfor your videos. Looking forward to the final observations and conclusion on the balancer issues
Coming soon!
You already proved this concept months ago but it's nice to see it proved out in actual real world off grid conditions. Nice. I wish Victron would make us a 16S fully programmable BMS. Another blue box opportunity , they surely will soon .
Some said, it was because of the 'old' battery and bad connections between bus bars and terminals. I wanted to see if they were right 😉
Yeah, the Victron BMS would be great. I don't know why they don't. Probably want to sell their own smart batteries.
So glad I bought my JK BMS last week before you nailed this down…. Now they will be sold out everywhere for six months!!!!
Hahaha, yeah, that could be the case!
Great video explaining the problem with full time active balancers and LiFePO4 batteries! Thanks Andy
No problem 👍
Another great comparison. Looking forward to see how the next 2 week test turns out. I bet the JK BMS sellers are getting an increase in sales due to you.
I'm keen to see the result as well... I can only share what I find out with all my testing. If people buy the JK or another is totally up to them...
Andy - I have been testing 5 balances on my 4S RV battery using cells like your - the 120a blue tooth BMS bleed balances such a low rate they are nearly 0.15v out at top it would probably take a month to balance!
1/The first balance was 0.5a surface mounted multi resistor that never switched on till 3.64v and latched till 3.60v - too high for regular charging and clunky - it also got quite hot
2/The second was 1amp bleed balance that again triggered at 3.6 which was thought to high for regular charging.
3/ The next was active 2amp balance switch mode balance with wire wound inductors - it worked but seemed to have quite high running loads of over 100ma
4/ A 1.5 surface mounted active cell balance that seemed to be very slow though did have twinkly lights - probably suited for smaller cells on e bikes
5/ An 5A active cell balance that uses small metal capacitors like yours - This was the most successful of all 5 and you could see it doing its thing nicely on the phone app - it worked in parallel with the BMS and brought the cells together nicely over night - it goes in to sleep mode at 3V - I wish it would be adjustable so sleep at 3.3v - it seems to have very low running loads
Just thought you might be interested
Fantastic testing, Trev. That is great information. I also have some other balancers but they are all crap and not really working with LFP. They may come from Li-ion setups and could work there far better.
Thanks a lot for sharing.
I so love how you do stuff. Great learning from you Andy.
Thanks 👍
Thanks again for all the hard work! I took the plunge and ordered 32 280Ah K cells from Amy, 2 JK's from alib. Still getting the rest to get started. Will use a Victron now and will get another one when I go to multiple fases. You have convinced me to go, there is no hard reason yet here in the Netherlands, but I expect this in the near future, the electeonics and cells are now hard to get and prices are still rising.
Woohoo, Edward. That's a huge setup with 28kWh of storage. It will be great!
Yeah energy prices won't come down for a long time any more, so that was the right decision. The JKs will work perfectly work the EVE cells. Do you get a discount from Victron when you buy directly from them, factory direct? 😂
@@OffGridGarageAustralia good tip about Victron need to investigate.
So, the Helltec balancers often have a run or enable solder bridge. It should be possible to use one of these generic voltage controllers with a relay to activate the balancer when the pack voltage is high enough to start balancing. In my case, I monitor my battery bank with a raspberry and will soon implement the switching (of the balancer) on cell voltage level with a logic in the raspberry. Then it would work like the JK BMS.
Edit: well, you just had the same idea. Still might be interesting for someone without victron charge controllers.
I have done something similar and it worked great.
Last week I replaced the raspberry with an esp32 which connects to the uart port of my daly bms directly.
The esp32 uses esphome which now has a module for daly bms. It monitors bms parameters and triggers the balancer via a relay when the difference is over 0.02v and the cell voltage is above 3.38v
Hi Holger, that's what I suggested at the end of the video. We will do this before we charge the battery again in two weeks.
I have given up worrying about if the BMS or the active cell balances are balancing the cells correctly, I now every three months charge the cells individually with a 3.5 V power supply and once its output drops to 800 milliamps I move onto the next cell I do this with all the cells still connected in series and have no More problems with cell imbalances. Is this the right way to go I don’t know but it works for me.
Food for thought with your setup is that maybe the two battery banks that you are having imbalance problems are supplying more of the load and thus cycling more then the battery with just the BMS on it. I have seen this before with parallel banks of batteries for some reason one battery does not discharge as quickly as the other batteries but instead takes charge from the other batteries. It would be interesting to put a shunt meter on each of the battery banks to see what current they have supplied.
Love your work.
Thanks Phil. Yep, I have done the same in the past and used a power supply. It can just take a long time doing that. With the JK-BMS, this is now something from the past...
I also don't have any balancing problems as you said. These two battery banks were connected to an active balancer for two weeks which caused the imbalance. I can see the individual currents of each battery bank through the BMS. I have never seen any equalisation currents from one bank into another. One bank can take significant less current than another one while charging or supply more current than others while discharging though.
Current from one bank to another occurs only when I had one bank turned of at the breaker to work on it for some time and re-introduce it. There could be currents from 20-80A for a short moment but nothing dramatic. I always make sure the voltages are not too different before re-connecting.
Once that eyebrow hair gets a little longer and connects to the back of your head you can clamp an ammeter around it and measure the current to see the deviation between that and the top balancer current. Staying connected and being one with your batteries is of the most importance. 🤣 No seriously, just a little humor, I do love all that your do for everyone with the batteries and the long hours you put into all this testing. Keep it up. 😁
Thanks man, I keep working on my eyebrows 😁
Good to see a test of what we had already summised. Maybe a workaround would be a relay that is enabled by cc or someother device to enable the active balancers.. or a jk BMS...
Yes, I will setup the CC for the next test to enable the balancer at 55V or so. They have a programmable relay.
I will be waiting for the next part of this experiment.....
Love your work Andy! Thanks as always!
Thanks Dave.
Another great vid Andy! Everything about the JK seems pretty damn good, I have one on order since watching ur stuff here like many others. Thanks for all ur great info!
Thank Evan. The JK is great 💪
Andy nice test...., go on.
Nach einem Jahr auf deinem Kanal, ich gebe es wirklich interessierten Bekannten weiter und gebe Ihnen nur deinen Channel. Sie sind auch sehr Begeistert wie Du das machst. Weiter so, mein Multi läuft, leider will die Sonne nicht so, in Norddeutschland, aber das wird schon :D, ein Bier für deine Heimat, *Prost* .
Danke Dir vielmals, toller Support!
Das gleiche hier unten keine Sonne, stattdessen eine zweite Flut 🤦♂️. Internet weg, Power weg... Power kann ich ersetzen, Internet nicht so...
@@OffGridGarageAustralia Verdammt und bei mir in Norddeutschland dürre, wir würden uns über regen freuen. Kopf hoch und vor allem immer über dem Wasser ( Pool ausgenommen) , hoffe das lässt bald nach und das keine gravierenden Schäden an Personen und Haus entstanden sind.
Good sets of videos but if you really want to see if the issue is the active balancer, you need to move the BMS and active balancer to different battery banks. It could be really just an issue with cells or the BMS differences.
You’re wisdom is far beyond you’re age !
I have 2 batteries. Both jk bms. I've done similar testing as you. I just leave the balancer on at 3.4v charge to 3.5v as a normal. I found an unbalanced pack (discharge,charge) with the balancer off then at the top turn on the balancer eventually top balances the pack again. I did this to 9mv deviation then tested 8 cells individually. All discharged full capacity. Life is easy Andy so leave the balancer on. Great testing and video. From So Cal usa. How goes the 1.21gw used solar panels? BTW I've noticed cell swelling over 3.4v if I charge above .2C. Charge at .1C no swelling.
The JK never let us down. It always balances at the right time.
Solar installation is in preparation. I've ordered all missing parts over the weekend.
The jk bms is fantastic, my 400ah 16s battery was around 50% state of charge for almost 3 months before i was able to get a full charge, but when i did, it was able to balance the cells perfectly. The only problem i noticed is the bms shows the incorrect voltage and the current is slightly wrong too, meaning that the % remaining display was wrong too. This can be easily calibrated in the jk bms settings and it looks like yours has the same error, im not sure if youve noticed but Andy, your jk bms shows almost 1v higher than the other bms and your set charge voltage, and the battery percentage shows 94% even though we know that it is now fully charged. I also discovered that this inaccurate display does affect the bms turning off discharge at the low cell voltage.
Thanks Lexi. I'm not too fused about the numbers the BMS shows. My point of truth is still the Victron Smart Shunt. The shunt also reports V and A to the charge controllers and inverter. I have 4 devices measuring SOC and voltage, they are all different, so I had to pick one 😏
@@OffGridGarageAustralia yeah Andy, I have found the same problem with thermometers, none are ever the same, you gotta just pick one u reckon is closest.
After the next charge cycle in a few weeks, if still all over the place in voltage differences, maybe swap the JK bms with either top or bottom bank, maybe the top, so you don't have to bend awkwardly, then if cell 16 is still weird on JK, you know it's not a BMS issue.
I doubt it's actually a problem with cell #16 because both battery banks (top and bottom) have the same behaviour but have different battery types (304Ah to 280Ah). I bet it is how the balancer works. Cell 13, 14 and 15 are high as well when leaving the balancer connected.
What if the bms without active balancer is really that good? Would consider shuffling the bms's between batteries? Or doing it the other way,, put a active balancer on that middle bms?
Buy a jk-bms ^^
The JK-BMS in the middle is really that good. Best stand-alone BMS on the market!
If you need to have a balancer connected all the time, it must be one of these two types (imho). Either a DC/DC to the lowest cell charge pump, or a double charger solution. The first balancer type grabs some current from a charger (a charger keeps a current constant, and so if some current go to the DC/DC, then less current remains for all cells), and sends this energy to a cell with the lowest voltage. No discharging happens. No unwilling disbalance. And the second balancer type uses two chargers, and bypasses the most charged cell, so it appears disconnected for some time, until other cells will have a same voltage. Again, no discharging happens. All the other balancer types which assume a discharging, are intended to be used only at a final phase, when a charging is completed.
Oh.. And there is the third type: a DC/AC to a multi-coil transformer. It also takes an energy from all cells/charger and feeds all slowing cells at once. Check out Sunkko balancer. Despite it uses only one phase in DC/AC as I suppose, it gives an idea. May be you could test it with your battery. I'm not sure in this case, because this type of balancers changes a charging current for multiple cells at once.
PS In another words, if a balancer keeps a same charging current for all cells except a most outstanding, I think this is fine to have it active all the time. To slow down the most charged cell is always better than to push up the weakest. This is interesting that a passive balancer makes the same )
And considering this, I'd suggest that the double charger solution is the best from many perspectives. But no existing controllers use it afaik
Hi Andy
This might be a little off topic. But can't you use a normal grid tie converter to connect to your off line garage to strengthen your 240v supply. I have wondered about that because you are totally off grid in your garage, so your 240v system in the garage acts like the grid.
This can only be done with a Victron Multiplus which can take the energy from another inverter in the micro grid and also turn it off.
Imaging the following: your batteries are full, not many loads connected and the grid tie inverter tries to export all its energy to the grid. That's what it is supposed to do. This would end in a big bang. So the trick is to control the grid inverter somehow and tell it to throttle down and even stop delivering power. This is exactly what the Victron Multiplus can do with a feature called frequency shifting. I will do this in the near future...
Andy, off topic sorry, but to be clear, you can use ur Tesla as a storage battery that you can charge AND discharge from, cant you, or would you need to make certain mods to discharge from a Tesla as a backup power supply for whatever reason? I like what ur doing here, & I have been considering some of the extra benefits of owning an EV, extra storage, redundancy & a car that could do a few hundred kms, would be a good 2nd runabout & reason(able excuse! Maybe!), to do something like ur. Even if I dont, love ur stuff! Thanks
This needs a special installation and home 'charger' which transfers power in two ways and also turns off the grid if the car supplies power. Tesla does not do that at the moment for several reasons. One of them is free Supercharging. You know what people would do...
Hi Andy, I am a bitt perplex with your last video. "Permanent balancing is counterproductive".... ok ... and you shown than during two weeks without any balancing, you have better results that with... If I extrapole a bit, it means almost after a super top balancing, you can eventually run everything without balancer. I guess the fact behind the scene is you have some Great LFPO cells .... very good quality. IMHO, the interest of an earlier balancing can come if you have some inohomegeous cells. For example whatever the starting balance voltage I am setting (3.45 ), my cells little by little becomre more and more unbalanced .... :( with my JKBMS...
It's not that easy unfortunately. If you need balancing or not depends solely on your cells but moreover on your setup. If you can recharge your cells every day the drift will be small, even they are B or C-grade cells. So the balancer of the BMS may be sufficient to counter that and keep the pack in balance. But we now see many people getting more and more storage with larger installations and it is likely that we don't fully charge for weeks if not months. In these cases, balancing needs some help...
Hi Andy, if we have two similar LFP battery banks one with Active while second is only passive balancer. In general will the first one (with Active balancing) a) consume lesser energy to charge if both SOCs were same. b) with same SOC level, will the charge time faster for active type.
How bad is a 100-millivolt difference? (i don't know) Since my plan is to run at 3.35 the active balancer would not be working as a top balancer. A scheduled once-a-month top balance at 3.6 is a possible plan for my batteries. A good video except for the BMS on the right seems like it needs to be replaced or updated or something, as you know. My older recycled battery bank may need more active balancing than a fresh bank. Where I live its almost always very sunny and rarely rains so it's interesting to see a bank not get charged up easily. Keep up the good work Andy.
Thanks Ron, the Heltec BMS on the right is not great. It is installed for testing purposes but I think I'm done now with it 😆
Absolutely agreed with your monthly maintenance using a balancer. That would be ideal. 100mV deviation is certainly not a problem as long as all cells are in the steeper area of the curve. Highest cell at 3.6V and lowest at 3.5 is perfectly fine, they will have the same capacity at this stage.
Looking forward to your next bms video👌
Yes, me too. It will be interesting in two weeks time...
Another awesome video mate 👍👍
I was just looking into ordering active balancers and JBD bms's.
New conclusion is scrap the balancers and instead order JK BMS's only??
Thanks in advance mate!!
Yes, go for the JK-BMS. It is awesome can replace the Daly and additional balancer you had in mind.
@@OffGridGarageAustralia literally in the process of ordering. Need JK 4-8s, 17s and 24s variants for different applications.
Would you recommend any supplier in particular?
@@oneman29 have a look on my website, there are links to all the BMSes you want. There is also a $10 coupon code you can use at checkout.
off-grid-garage.com/battery-management-systems-bms/
@@OffGridGarageAustralia I just got the chance to rewatch the premiere and realised you mentioned it right at the beginning, which wasn't works for me when aired.
But thanks again for videos and responses mate! Awesome stuff 👍👍
I don't quite understand your issues with the active balancers being connected all the time. Ok, my battery system is a lot smaller than yours, I only have 4 cells. But I never see an imbalance of 100mV, typically all cells are spot on the same, maybe 10mV difference sometime. I trust the balancer that much, that I meanwhile disconnected the BMS. Voltage protection of inverter and charger is enough and it takes out an additional point of failure as well as less resistance (heat losses) in the system.
Could it be that your BMS and your balancers somehow work against each other?
Grüße aus dem Nord-Schwarzwald (es regnet schon wieder).
Andy, i noticed both the Heltec and Overkill have cell #16 very high. This cannot be a coincidence?!? I have a 2P16S 2x280Ah setup with a Daly (bought it B4 I saw your great video's which are so helpful to me now) and also in my case the cell towards the end is always higher. What's your view on that?
That is caused by the active balancer for some reason. Others have had the same issue when having this balancer connected all the time. For some reason, it slightly prefers to charge cell #16 more than others if it has enough time. Could be part of the balancer algorithm they are using.
Hey Andy, What if you turn the balancing feature off on your OverKill BMS and keep the Active Balancer continuously connected? So only the Active Balancer will perform balancing function. That will in essence be what the JK-BMS is...No?
Thanks Eban. The essential difference her eis WHEN you turn on the active balancer. The JK BMS has a balance start voltage when it activates the balancer while the active balancer will balance all the time. And exactly that is the problem. You don't want it to balance all the time.
Great work andy!
Hi Andy, I've been using JK BMS on my 8s pack and it works great. I am curious, what is "Cycle capacity" and looks like it is changing over the time. Can you please clarify? Thank you, appreciate your channel and all you do.
Thanks Oleg. Cycle capacity is what the BMS observes you cycle the battery with. So this is basically what you real capacity you use over time from your max capacity of the pack.
@@OffGridGarageAustralia Appreciate you replay, that clarifies things!
I have enjoyed watching your channel and your progression since you received your first 16 cells. I have been about a month behind you in testing, playing with, building batteries. But I also now sell them. I have a few comments about your balancing issues. First I don’t trust active balancers enough to leave them connected. Unnecessary tech in my view. I have been testing one for weeks. I intentionally put a 12v 230ah pack together with one cell fully charged and the other 3 almost discharged. I connected the active balancer and it moved some power around until the high cell went below 3.38 then it would stop. But the light stayed on. Since the stop happened twice I connected a power supply to the high cell. Set the output at 3.6v and 800 watts. It has been connected like that for a few weeks and the 3 low cells are slowly charging (judged by voltage) and the high cell sits at 3.56v. So the active balancer is definitely taking the 800 watts and moving it to the other cells. So configured like this I guess you could top balance your battery with this Method. But why would you? In 1/10 the time I can put the pack in parallel and top balance it in a day. So I can’t get my head around why I need one. My other comment surrounds cell balancing. I have come to believe that we place too much emphasis on exact balance between the cells. In my view as long as when the highest cell hit 3.55v (my max cell v setting) all the other cells are in that steep area of the charge then why care if they are 100 mv out of balance? As long as all are over 3.4 before that shut off happens you are dealing with under 1% capacity loss due to imbalance. If 2.8 amp hours means that much to you, you need a bigger battery. I have watched batteries that seem to be perfectly balanced for a year. Never more than 30mv out of balance even at 3.5v. I have seen others that would have a cell at 3.45 and another hit 3.55 and the BMS stops charging. Their capacity was almost identical to the first test done on it when it was perfectly balanced. So my question would be: if the pack capacity is not changed remarkably when the cells are 100 or 120 mv out of balance at the top of the charge, who cares? I would not be concerned unless I saw a reduction in capacity. If I saw that, or saw a 200mv delta when one cell is at 3.55 I would take the battery out of service for a day, remove the bus bars and connect it in parallel
Hit send just a bit too soon! I meant to finish with connect in parallel and top balance it with a 3.6v power supply. Put it back together and see if it happens again. If I had to do that to a battery every 6 months or a year it would not bother me much.
Fun watching your channel, keep it up! Although I have trouble believing you need more capacity than you have now! There is a huge amount of energy in the off grid garage. Well done. I’ll keep watching.
Thanks for sharing your thoughts, David (you can also edit your own comments after you have sent them😉).
The method to top balance your battery with an active balancer makes sense if your pack is already built and it would be a tremendous effort to take it all apart again and connect the cells in parallel. You can also keep using the battery system while doing this top balancing, so nothing needs to be turned off if the power source is strong enough to power your loads.
But yes, I agree for a new battery, it is faster to parallel them first to balance them.
Yes, I fully agree with you on that argument of balancing if cells are not running away and are all in the steep area of the charging curve ( I made a video about this a while back). The capacity is then already very close together, even voltage differs. So practically no gain when balancing them any further. We have done all this testing here on the channel and charged a cell to different voltages to measure the capacity. Hence I now charge mine only to 3.45V and let them absorb for a while until they all catch up and are saturated.
I certainly don't need all this capacity right now. It basically matches the capacity in the Tesla battery already. This is mor for learning and testing purposes. There are more batteries coming in the future though. Not that I need them but...
Thanks again for sharing, great comment.
@@davidwhite47 great comment David, keep watching Andy’s vids, he has got a few to get thru, I haven’t seen em all yet but probly getting there soon. I have made comments & then watched another vid & thought, okay well that answers that, I can see where he is going to some degree here, Andy has a 45kwh Tesla I think, so 44kwh battery is probly a good project area, for ‘Andy’ to start with anyhow. We all made a lot of comments about how to hook it all up to his house, but there were actually a number of complex issues & concerns for Andy regarding that matter, & I believe he went down the right path regardless of everyone’s comments, & he didn’t want to mess with his already installed system & FIT, fair & prudent call.
You obviously know what ur doing David, & Andy is a pretty good listener too IMO, I like going thru many of the varied comments here, I learn a lot, and I think so many others do too. Some of these experiments & tests help us understand for when sh*t happens (when ur away for awhile), and ways we can combat these potential problems that may well never happen to many of us. Didn’t mean to bore u with a lengthy comment, & nothing wrong with urs, it was well placed, but I do love this channel, & I think Andy’s logic seems overall pretty sound, & he doesn’t mind saying if he thinks he has f**ked up either, & he does ‘fiddle’ with things pretty hard, so I think he’s doing at least 4 Frogs as he puts it, “Humble is the Wise man”, Cheers!
Andy is THE balance king. But sometimes I wonder if the capacity % gain/loss is all that important also. If they’re coming back together at the top knee you have to be pretty close to real good. Gotta love that over the top spat man.
Hi Andy! Is that plexiglass on your battery shelf? Is it safe enough with melting point at just 160 C? P.S. Love your videos!
I have proper covers made from aluminium. But yeah, it does not burn and melting point is around 190-200°C. I tested it in one of the videos...
Oh man.... Hut ab...
Also ich hätte ja viel gedacht aber das hätte ich nicht erwartet.. Mir war klar das die Balancer dann nur noch so wenig leisten.. Ich fahre die Akkus von etwa 5 bis 90 Prozent.. Also kurz vor der steilen kurve... Somit ist mir das noch nie aufgefallen... Ich glaub ich hab viel Arbeit am Wochenende 🙈
Hahaha, ja fahr die mal bis 3.5V hoch, dann wirst du es sehen...
@@OffGridGarageAustralia ja scheinbar sollte ich das dringend mal machen
Thanks Andy
I use a simple over/under voltage relay and use it to turn my active balancer on when the bank voltage goes above 27.2 volts and then turn off when it drops below 27.1 volts (for my 24V battery). The relay I use can also turn on at the low end of the voltage range if I want it to bottom balance, but I have not enabled the undervoltage setting on the relay. Seems to work pretty well and its cheap and simple.
When the battery is charging from mppt charge controller and the bms disconnects the battery due to high cell voltage or temp etc does it damage the charge controller if it is seeing full pv power and the bms isn't connected via a communications cable?
It does not damage the solar charge controller. They usually go in float mode and still supply solar power to the load if they can.
Hi , I see on the JK BMS that the Cycle Count is 0 after 82 days ! How did you do this ? For me is one cycel at 2 days.
I changed the capacity settings on the BMS so it things it's a new battery now and starts from 0.
Hello Andy. Another amazing video! I just received 2 active balancer for my futur 32 cells batteries sets JKBMS controlled. Should I sell them or any interest to keep active balancer when I see your results?
Hello Andy,
The heltec can be good especially if the solar system is connected to the grid.
For example I use a seplos bms and it will fully charge the battery and then disconnect the charging so that the exces solar power can be fed in the grid but if a cloud is passing there Wil be a short voltage dip and some power will be used from the battery and if the cloud is gone the voltage Wil rise and charge the battery again this will result in a lot of rapid charge and discharges is one day. For example the seplos Wil stop charging at 100% and only enabled it under 90% to keep this rapid cycles at a minimum
Hello Rutger, thanks for your comment. I find this fascinating that you use a BMS to terminate charging! Should this not be the role of the solar charge controller? A BMS is for protection only, not regulate the charging state of the battery.
@@OffGridGarageAustralia yes if the system is off grid I would agree.
But if the system is on grid it's not possible if you turn of the mppt you will also not be able to feed back in to the grid.
For now this is the only solution I found not to fast cycle the batteries at high state of charge. Before with the other setup the batteries got pretty warm on a cloudy day and the state of charge was going up and down from 96 to 100%
Now it's yust going to 100% and only drops to 96 on a cloudy day but no rapid charges in between
@@Rutgeroppenhuizen The BMS should not disconnect charging unless there is an OV, UV, OC or OT situation!
The battery will take less power once it gets full which the solar charge controllers keep sending energy. What the battery won't take, goes into the grid. Once the battery is fully charged all solar power goes into the grid and the battery floats.
There is no cycling of the battery at 100%.
If they get warm or you have watched them cycling between 96 and 100% there is something fundamentally wrong. Could bad faulty hardware, wrong settings or bad system design.
agree with you andy. let's see what the next test brings
Time ^^
As mentioned the last time I have the opposite experience. Frankly, I do not charge or discharge my 250Ah with more than 30A so the 2 parallel 5A active balancers have enough time to catch up with any potential deviation.
I will leave em connected all the time.
How is it with yours, if you hit like 40 amps of charge? I quite soon get cell voltage limit on my dalybms cause my 1A active balancer seems not to be able to catch up. Then it falls quite fast (minute) back to 3.25 as the rest is and the game starts over.. (16s, 200ah, calb lifepo4)
Is that normal?
Très bonne analyse. Merci ANDY
Merci beaucoup!
I look forward to the results in 2 weeks.
Me too, John!
Before you do that testing of acvtive balancer. Did you check all cells resistance???
Andy, interesting video on Meine Energiewende in the future, about how to make a JK bms visible on victron's vrm
Very overrated in my opinion. For what reason do you want this? If the battery gets low, the inverter will shut down any way. If the battery gets high, the solar charge controller will stop charging. All this happens without communication.
I really don't see a benefit from having this communication. It just ads more to the complexity of the whole system...
I left a comment on Jens' channel.
Andy, on those active balancers, the pad that is soldered with "RUN" label, you can unsolder that connection and insert a relay connection controlled by something else like your raspberry pi, triggered at a specific voltage or set of parameters. Or... you could build a simple divider circuit with a relay, so it would closed loop turn on at the top of the charge only.
Hi William, that's what I said in the video at the end 😁
30k Subscribed coming up Andy!
An I was offline again! No internet since the recent flood last weekend .
That is incredible, 30.000 subs. I need to print new numbers for my door 🥳
Andy I'm in need of your professional advice in a bad Way!!! I have 24 nissan leaf modules in a 24 volt configuration. I need advice on a bms. I am running them without a bms and people say it's dangerous. I'd rather not burn down my camper so I'm trying to find a good, easy to understand and set up bms. The leaf cells have a weird top voltage of like 25 volts and I take them down to 20 volts. Do you know of any good quality bms that can be adjusted to those voltages? I've never had a bms before so it's all new to me. Any help is greatly appreciated
What is the configuration of these cells? How many in series, how many in parallel in one module? How are the modules connected together?
@@OffGridGarageAustralia this will sound confusing but here goes. Each module is 2s2p. I have 12 modules per stack. Each stack of 12 is 4 modules in a group and each group in a series of 3. Then there are the 2 stacks at 24 volts in parallel. So it's 2s2p4p3s2p
I could do a 6s bms if I could find one that supported a 4.2 nominal voltage per cell. I need 2 bms that are 6 s but yes it would have to have a high voltage of 25 volts and all bms I see are for lifepo4 and have much higher voltage for a 24 volt pack
I don't have solar panels or big battery banks, but I had to discover battery balancers myself about a month ago after I got annoyed that Lead-Acid batteries in 24V cheap consumer UPS die so often... You can put high quality 8-10 years lifetime batteries in it, and after 1-3 years one battery will almost always fail... Of course, these UPS never have any balancing in them… So, now I've added a simple 2S active balancer to my UPS... It didn't solve the problem entirely because it turns out that one of the batteries is half-dead anyway, and the balancer can't bring its voltage to the same level no matter what... And the capacity is roughly 50-60% of what it should be... So, next week I'll install fresh batteries, with a balancer, and I hope they'll last longer this time...
In my situation, I bought some pre made batteries (3x 130ah lifepo4) which run a jbd bms. I have found the cells don’t balance at the top or bottom well. I am getting 330ah from a supposed 390ah total. So I have bought an active balancer to help get both the top and bottom ah out of the pack. I keep seeing people test these active balancers with one cell fully charged and the others depleted which is not what these active balancers are designed to solve for.
That's a good example for using an active balancer. Thanks for sharing, Michael.
Andy, if in two weeks time (or so), your theory is proven correct, that active balancing in the flat part of the curve is contraindicated, maybe show us how to automate. Can a simple relay be utilized to somehow switch on the active balancers if voltage reaches a certain threshold?
PS: Maybe tie-in arduino somehow. . .
I talked about this at the end of the video 😉
I saw on the forum a low voltage disconnect board setup so the active balancer would stop below some voltage e.g. start above some voltage and thus "helping" the BMS.
But, would this also be an option for bottom balancing for periods where the lack of sun doesn't give us a full charge?
Andy, the active balancers are too small for your battery size. You can parallel them. So try putting the two 5A ones together on one battery. I just bought the heltec 10a one for my 8s 24v batteries. It will make a difference as the amperes used at 0.1v difference will be 1.2A x 2 = 2.4A - which is equivalent to your JK BMS.
Yes, you can parallel them. But this would also introduce even more complexity to the system. Once the balancer is running only at the top of the charging curve, it will be fine. I also have a 10A active balancer here. But it's only for a 4s battery.
@@OffGridGarageAustralia i would love to see the 10a one being used 😃 especially as mine are arriving shortly. Also, would appreciate some ideas on how to safely modify a pre built battery that has been spot welded. Is it best to solder the balance wires on? Or something else?
Hello, I am a scientist at a German university and I am investigating LFP cells with a special test rig. Unfortunately I can't give more details, but I can explain where the problems with the active balancers come from.
From my own tests I know how precise the active balancers are. If you supply the balancers with a power supply at the highest and lowest potential, you get partial voltages that are accurate to the mV.
And exactly here is the problem, the voltages at the cells are dependent on several factors, such as temperature and the slightly different internal resistances (when they are charged and discharged).
So the cell voltages are not absolutely the same in operation even with the same SoC. Nevertheless, the balancer tries to equalize the cell voltages.
I would therefore recommend using the active balancers only for top and bottom balancing.
Indeed - but if you look at the specs of this specific active balancer (Heltec 5.5A) you will see that the balancing will occur in a gradual way from 0.01 to 0.1v differences, with the 0.1v difference being 1.5A for 8S. As we all know, the LFP voltage curves are flat in the middle, so the balancer will actually put itself to sleep until it sees a higher difference. Also as we all know, LFP voltage curves happen at the bottom and the top of the pack. So in essence, under normal operation in say a house battery, these balancers will top and bottom balance your system. Also, the manufacturer states that
Thanks for your comment and support of my theory. We have made such a test a few months ago already where I found the same result. The balancer was permanently connected to a 16s battery and basically caused an imbalance over time which it could not re-balance once fully charged. Some viewers said this could have been caused by the fact the my terminal to busbar connections were not optimal (higher and different resistance) and therefore the balancer balanced out the voltage difference it saw.
This test here was to demonstrate that the problem is not caused by the bus bar connections but more likely by the variation of the cells as you described them.
In the next test, we will see how different the cells will perform when fully charged again without the balancer.
@@OffGridGarageAustralia Of course, it is always an interaction of various influences. The contact resistances of the busbars can also contribute to this. However, this should not be overestimated. There is also a thermal influence that should not be neglected. If a cell heats up more, its internal resistance drops somewhat and thus its voltage. At the busbars and the cells in the middle of the set, the heat is evenly distributed. At the edge cells with the transition to the wires, it may be that additional heat is introduced from the wires. Therefore, the voltage at outer cells can be lower, which leads to a continuous recharging of the active balancer to this cell.
Regarding the answer of Micheal Wood, I could not confirm in my tests that the active balancers go into a sleep mode when the cell voltage is approximately the same. I can confirm that they have a lower turn-on threshold as stated by the manufacturer. However, only the first cell is considered for this.
As I said before, my recommendation is to use the balancers only close to the charge and discharge end. This can be programmed e.g. with a Raspberry PI or also the Cerbo GX (e.g. Node-Red). There is an "Enable" solder bridge on the balancer boards, which you can lead with wires to a control relay for example.
I'm building something like this right now with my PV storage. It just use an additional cell voltage measurements and control the Multiplus inverters according to their charge status.
I found this video by searching for my issue being similar. I have a cell in my 4S system that always reaches the final voltage before all others but also reaches the lowest voltage before all others when under load. The supplier recommended adding an active balancer, which I have on 24/7 - after 5 months of testing, the same cell still reaches high voltage before all others AND still reaches lowest voltage before all others. To me, this looks like this one cell has a lower capacity than the others maybe because of degradation. This pack had only 13 full cycles since put together. Should I try to disconnect the balancer when discharging and only have it connected when charging above 3.45 V or do you have other suggestions?
Hallo Andy! Mich würden deine (dauerhaften) Einstellungen für das JK BMS interessieren. Insbesondere Bulk/Float Voltage (Ladespannung WR), OverVolt und UnderVolt Protection im BMS. Gehst du mit deinen Werten 20-80% oder 10-100% ? Ganz liebe Grüße aus Deutschland
Danke Dir Christian. Mit LioFePO4 kann man getrost bis 100% laden und die Energie auch nutzen. Ganz entladen tue ich den Akku jedoch auch nicht, ausser ich teste etwas. Mit der grossen Batterie nun, komme ich sehr selten in den Bereich von 3.0V oder darunter.
Im uebernachsten Video stelle ich das JK-BMS 4s vor und da gehe ich genau auf alle Einstellungen ein.
@@OffGridGarageAustralia Danke, da freue ich mich dann besonders auf das übernächste Video. Bleib am Ball und halte uns up to Date. Ich schau aber alle deine Videos gern. (auf den anderen Kanälen auch!)
@@CryptoOpa Vielen herzlichen Dank dafür.
Hi Andy, greetings from Finland, we have here a storm and 6 degrees below zero and no frogs... Have you measured the voltage loss of the bush bars with a high load current? That would be a very easy way to check for a good contact. Just measure the voltage from the tip of the battery bolts between the bars. Br, Eeli
Ive noticed you have the Breaker for each bank AFTER the BMS. I was considering a breaker before the BMS (multi bank solution, similar to Andy's).
Pro and Cons? I just think a breaker before BMS will protect bank if BMS has a meltdown.
That was part of my design, regardless what will happens, the BMS will still be connected to the battery. In case of an emergency shutdown I still have the BMS to give me all kind of information. Also for maintenance, I flick the breaker and can work on the battery including the BMS. I can let the BMS balance this one pack over night for example.
I think battery and BMS is one unit and should not be separated. Either is useless without the other.
@@OffGridGarageAustralia makes sense. I also realised your breakers are double pole when i was drawing my diagram and realised it’s actually protected on either side
I'm having the same problem with ready made drop in batteries. I'm tempted to bust the seal and try changing the BMS.
Do they come with a balancer as well?
@@OffGridGarageAustralia Yes they do but they are set up as the only form of protection. Its easy to lose some capacity when the bms is conservative, the battery monitor cutoff set above that then the inverter above that again. Homebrew batteries are the way to go.
Is there a link to the follow-up test? Thanks
Andy, have you had any experience with the Batrium BMS?
No, I was in contact with them but felt, this is not the right BMS for my setup. I wanted several independent batteries which are not reliant on just one BMS. With my setup now, I can just turn one bank off completely without affecting the other two. I doubt this would be the case with the Batrium.
I did see that issue with the same type of balancer on my bank (a 48v 150ah). back when I had a 8x 250ah AGM´s, to help balance the voltage throughout the two banks (4 each) I would connect the batteries between the two banks. this means that both banks were in parallel on all batteries, not just the end units positive and negative. I imagine you´ll be able to do it on lithium as well. Just a thought that might help when you got multiple banks...
Its totally doable to parrellel all cells, balance also seems to improve because of it. Its a lot of extra connections and much more difficult when you have to troubleshoot to find a failing cell.
@@jakeandrules7724 agree, but this way it passively balances itself. I imagine that if one cell is bad it will clearly reveal itself.
did you have time to put the used solar panels you bought?
Hell, no! No time since. It will be here on the channel...
So, if the active balancer should not be connected all the time, how would you turn it off on the SunKit battery once you close up the case? Can you turn it off remotely?
That is a very good question, Ricky. I would like to have either a physical switch on the outside of the box or a relay which turn on at a certain voltage. These balancers don't Bluetooth so no remote option there.
What do I think? I think this video raises a lot of questions.
First of all, how much cell deviation is allowable? 1mV, 5mV, 50mV, 100mV. Depends who you ask I guess.
Do any of these active balancer come with blue tooth so you can chance the parameters like you do with the BMS. If so you could then disable balancing below a certain cell voltage.
How long before BMS's come with inbuilt active balancers.
Also this video suggests that a BMS is not really needed once everything is set up correctly. Once the battery is balanced, so long as it is never fully discharged it should be fine. After all the BMS should not be there to stop the battery charging. The charge controller should do that. Maybe not in your case with multiple batteries, but in the case of a single battery.
All 3x BMS’s had BlueTooth,
which is how Andy got the displays.
Each is programmable, in their own way.
The value of the BMS is to keep a lithium fire from occurring, keep venting from occurring for more stable chemistries, and to otherwise keep from destroying the batteries.
I have been struggling with the question of using a more volatile chemistry, never charge it to 100%, then do I really need a BMS, or is a balance board all that is required if the inverter shuts off when the pack is too low? (EGO batteries run like this, and I am generally pleased with the results.)
My only concern is possibly killing the welded packs when the weakest cell fails when it will eventually drop too low. This known eventuality keeps pushing me back to using a BMS.
I just bought a pair of welded packs that have no BMS, so I am now about to make that decision.
Thanks Peter, that's all good questions raised. I think as long as all cells stay within the specs, balancing is not really necessary unless you see a drop in capacity.
The JK-BMS I'm using has already an active balancer and it works flawlessly.
You must have misunderstood, a BMS is always needed as I said many time in my videos. It's a must have for your battery. And, as I said many times in my videos and in this one as well, a BMS is not there to control charging. But the Heltec BMS does exactly that and I said, it is wrong.
On the Active balancers, Beware if you try to unsolder the RUN pads, to connect switch or relay. Also only use small gauge wire like 22. I soldered on 1mm wire, but one of the pads came off! There is a very small through hole plated connection. I repaired it by scraping the other side of the board, and soldering a thin wire there. Am using a 24v relay, controlled by XY-CD60L - LCD screen, programmable voltage relay module, in OUT mode. It is about 0.1v reading higher than the true battery voltage. Turns on at 26.8, off at 26.7. Sometimes, when the voltage is falling, it turns on and off, briefly. There are also some timer modes, I have not investigated. Middle SET button clears the flashing display when it turns off. DOWN button is also a manual ON & OFF override, doesn’t always work, so maybe subject to the voltage settings. Holding the SET button allows changing parameters. Pressing SET cycles through displaying the settings.
Thanks for the info! Yeah, these pads seemed very tiny.
Andy,
Does Mrs.OffGridGarage also dream about internal battery resistance and not enough solar irradiance?
Ask her 😉
Could I put alligator clamps on a active balancer and do maintenance balance on my batteries ? I have multiple batteries with jbd bms.
That should work just fine. Just make sure the clips are secured connected and in the right order.
Hi, I need to setup my batteries in smart shunt 500a and I dont know what is the best voltage for synchronize SOC, by float or by absortion voltage? Thanks for you very good vídeos.
Great question, I will soon go through all the devices I have setup and explain the settings of each.
I have set 55.2V as absorption in my solar charge controller and have the smart shunt set to:
55.1V charged voltage
10min detection time
0.5% tail current
All three parameters need to be true to reset the shunt to 100%. You may need to adjust the settings a bit to your needs depending on your setup.
Why is always cell number 16 totally out of balance? It's the same case with my 16s pack. After having had the active balancer 24/7 connected, cell 16 hits 3.65v way faster than any other cells/ shows the highest SOC. 0.2v cell difference. I use the same active balancer.
That is something I observed as well! I also found cell 15, 14 and 13 are higher than the others as well. It must be how the balancer works. I've never seen this when I connect it only at higher voltage, only if left connected 24/7.
Andy swap the cells that are overcharging and swap the BMS after that. I am 100 percent sure the problem will follow the cell and it has nothing to do with the BMS or Active Balancer. Also measure the internal resistance of those overcharging cells. I am sure it is different. I am guessing if you check the capacity of cell 3 and 16 individually. You will find it is slightly less than rest of the pack. Balancing is not the issue here. Balancer cannot fix capacity issues
These are not the cells. If you read the comments here, quite a few people have the same issue having a balancer connected 24/7. Also, two different battery banks, two different BMSs, same result... And it seems to affect #16 every time for some reason...
Even if they have different capacities, it should not matter once they are top balanced.
@@OffGridGarageAustralia Care to see if the third active balancer on bank2 put it at imbalance. Just remember these balancers will have no chance balancing in real time at high amp charging rate It will balance overnight. Make sure to turn off the solar charge controller overnight. take the reading in the morning than turn the charge controller on. I know on my Dali BMS it was 200 or 300mv deviation before it started balancing the cells. I am not sure what it is for Active balancers. I will also turn off passive balancers on the bms. I do appreciate your work here. Thank you
@@wasifsyed1085 thanks very much.
i discharged my batt at 100a til 2.9v it is a jk bms and mos reached 68 degree c and batt t1, t2 reached 42. batts are in a box. is that temps safe? Where is the unsafe mark?
You need to lock into the specs of the batteries. The EVE have 55°C as max discharge temperature. Not healthy though, temperature is a killer.
You topped again Andy. Thx
How do u know when all ur cells are actually balanced it seems like they never actually balanced or the identical same voltage on these bms out here
Hello , you do a great ~ Job thank you I’ve been following you for years ! I have a very good Question for you - in You’re Wisdom I have 2 Lithium Battery Banks 1 - Lithium Phosphate 48v 3.2v 280Ah which I actually have 25 PCS Batteries of the 3.2v & an LTO 2.3v 40Ah & I have actually 24 PCS “ Question - can I use an Active Balancer say for S- 25 wires which the batteries are not connected together but the Balancer will help regenerate the 15 PCS Batteries connected together in series for 48v but the other 11 batteries will help Regenerate the 15 batteries in Series when they drain down and when the Inverter charge controller charges the 15 PCs batteries that’s on the DAILY 15S 120v BMS the Active Balancer will transfer the electrical voltage from the 15 PCs to the other 11 batteries which are not in Series ! You following me ? I’m sure you are with all you’re Experience & Knowledge ! Will this work ? The inverter is an EASUN 5KVA 230v PURE SIN WAVE Inverter Charge Controller 48v GVW ! And another question I want to take the 230v Hybrid Solar Inverter the L1 is Hot 115v & the Neutral is Hot 115v at 5KVA is 98A in only an Emergency electrical lose I want to be able to energize my Breaker Panel I’m in the USA which is 120v @ 100A my Box is a Square D Home Line what I see to Back Feed this Box I Have to Use a 20A Double Pole Breaker and the whole box would be 1 Phase at 115v at 5KVA 98A but my house we use about 3 KW a day - and if it’s a grid down only refrigerators and gas heat with the sump pump would be on I have No 220v in my house so possibly thinking we can run at 1 Phase 115v pure sin wave inverter & do you want a little bit better take a GM 10 SI High Amp Alternator wire 1/0 wire 130A because the Alternator is 120A wire it with 1/0 straight to the Stator the Brass winding under the rear case which produces the Purest Sin Wave 120v spin the alternator with a 12v DC motor speed control the only thing I have not found is a Module or voltage regular yo monitor the battery bank and turn on the 12v DC motor to keep the Battery bank Charged ! My alternators are a GM 10SI high Amp 110A & a Big Block Low Spin GM 10SI 120A & a Ford Mazda 150A Alternator ! And 3 - 12v DC Motors and Charge controllers !
Which kind of JST connector do the balancers have?
Nice vidéo !
For the heltec, I found is great option if it cut charging at 100°/°. If WE want keep batterie at 80°\° max, WE just have to parameter the capacity if thé batterie at 80°/°.
What do you think about that?
Victron should add functionality to the Smart Shunt that allows you to dictate how many amp hours you charge into a battery and then communicate with SCC to stop the charge as opposed to relying on voltage alone. Maybe that way you can actually charge up to 80- 90% reliably.
It depence on the situation i Guess.
I have actieve balancer on Every 18S pack (x3). They limit the time it takes to top level by 2 days!
The thing to note is that i am running it parralelled on a batrium that is connected with the victron via canbus, the batrium will limit the charging current on the top level and gives the balancers time to top Balance. My cells are used cells... Some of them are allways chargeed faster and discharge faster. I ran it for months without the active balancers and it took for ever to reach top Balance.
Yeah, OK, if you limit the charge current, that's a different situation then. I don't want to do that if the other banks are still able to take energy. We will see in two weeks time.
my active balancer has been on for a year now , no issues
Do the separate active balancers have an option to only turn on above a certain voltage or else have a way to trigger balancing via a relay? It seems the JKBMS already has this built in.
The separate active balancers being used have no smarts in them. They are completely passive so there is no way for them to control that but as Andy pointed out in a previous video they do have ability to connect to a switch to turn on/off. That is why he mentioned using relays of the charge controllers in a future video to turn them on only after the charge controllers see that they hit 3.45V like the JK BMS already does.
Thanks David!
Just a correction Andy:
The QLD electricity grid is *always* dominated by fossil fuel energy (coal and gas). In the last 7 days, renewable energy *at its peak* provided 25-30% of grid demand for short periods in the middle of the day, with the rest of supply coming from from coal and gas power plants. Last week renewables contributed 16.2% of the QLD grid demand. QLD grid is *always* very fossil heavy and it's the most carbon intensive grid in the country.
I am sure he meant he is paying the extra from his supplier to be supplied 100% renewable power for his usage. Yes the grid as a whole has a long way to go for fully renewable.
@@jasondevine6014 While I get the idea, physically it's false accounting as it doesn't result in an increase in renewable energy supply. Paying more doesn't make more sun or wind available. All it means is the proportion of fossil fuel consumption allocated to everyone else on the grid is a bit higher.
If only 25% of the physical supply is available from renewable sources, then it matters little how much extra you pay for it, there is still only 25% renewable supply available.
Thank you so much for this info!
Can I use it with gel/Agm batteries 4 inseries 12v each for 48v system??!
Nice research 👍
Thanks!
Dear Andy, how can we combine LTO & LIFePo4? When you'll start reviewing LTO? I'll be your fan :)
Very difficult to combine them in one system... I'll probably to a LTO project soon'ish.
The solution is to only allow the active balance when a cell is >3.44v. The external active balancers are not programmable but you can turn them on or off manually.
Yep, that's what I explained...
@@OffGridGarageAustralia Your videos are a hell of a journey.... I know you know what you are doing... I love the demonstrations. It's the best way to teach. You are a great teacher.
Definitely added a JK to my shopping list. Been running the Overkill for a year now. Even without an active balancer things go out of whack way to often. I like the fact you can purchase it with a heater function too. 5his would eliminate the thermal controller I now have stuffed in my battery box. Just a cleaner and more ideal setup all round. With a nicer display to boot.
Thanks Landon, the JK is definitely a great BMS! You cannot go wrong with it.
Thanks for all the tests this helps me a lot for my solar system ^^
No problem, thank you.