I worked for British Telecom for many years. The telephone exchanges had battery backups and a diesel generator. Each battery was 6v lead-acid, and wired in series. Because of imbalances, but it was an acceptable problem / consequence, we had to change the batteries often, and certainly more regularly than you'd expect. You're absolutely correct, but most people will be happy to wire two 12v in series. 😉
Yes, and a backup station is not made to cycle all day, so i expect the imbalances to be less visible. This video doesn't really focus on lead-acid. Maybe i should have talked a bit more about lead-acid.
@cleversolarpower Sorry, I didn't explain too well. The batteries were always used. Mainly to smooth out the feed and ensure a steady DC supply. They were mains charged, but generator during a power cut. So the batteries were in continuous use.
@floki5353 To be honest, I'm unsure. Nowadays, yes. Back when they were the strowger sets, I don't think there was unless you count the huge capacitors?
Lead acid in series is a bit easier. That chemistry tolerates overcharge which it dissipates as heat as vaporizing electrolyte. This allows the series string to be periodically "equalized" to a higher charge voltage which ensures all series cells are fully charged. Electrolyte management is a separate issue. After using lead for years, running LiFePO4 is almost magic.
Completely agree with you on this, and this is something I've long stated. SOC divergence can be seen on maintenance free lead acid systems too and they need an external balancer to keep them in check. Open cell wet lead acid allows one to simply over charge each cell to bring the batteries up to the same SOC and then replace lost electrolyte.
People have been connecting batteries in series for years without issues especially those that use balancers. Some people actually started out with a small 12v system and later realized they want to move to higher voltage without discarding their already bought batteries. This is why many people usually series their batteries.
I have a 12V system and use agm sla batteries wired in parallel. I routinely disconnect and test each battery individually so as not to get any false feedback from the testing. I have not had any problems as yet, and everything seems to be in good working order and balanced.
@cleversolarpower , I have been told that if you have one battery that won't hold charge, it can drain your other batteries that it's connected to, and if left connected to the other batteries, can damage them. I don't know if that's true, but it does sound plausible. So I err on the side of caution and test my batteries on a regular basis.
So asuming i have a full 24v battery in parallel and i want ti upgrade to 48v will i add another 24 volts in parallel or i should buy single 48v and remove thr 24v?
Open cell flooded does drift in a similar way but you have the option of simply over charging the batteries to bring all cells up to full charge and periodically replacing lost water. You can't do this with maintenance free batteries since over charging there for flooded cells will see loss of electrolyte over time; AGM and gel types will be damaged by over charging.
This used to be a problem for me with my acid batteries. But now that I can log into each battery individually and monitor it through its Bluetooth BMS I can see that they are staying well-balanced. It seems that if they were to get out of BALANCE the one that had the higher voltage would have an automatic cut off when it reached a voltage too high.
@cleversolarpower One question please, I have already bought 3 12v 150A lifepo4 batteries, the idea was to buy a 4th battery to be able to achieve a 12, 24, or 48 configuration. Watching your video it makes a lot of sense, now my question is the following, do you recommend me to finish my 12v string connected in parallel, or make a 2P2S to make a 24v system?
You can still finish your system. I recommend watching how they behave (measure the voltages of each battery) and add a balancer if needed. You will need one over time anyway.
No, this video is only for lithium (lifepo4). There are no 24 or 48V SLA batteries available as far as i know. But why would you use SLA batteries anyway?
@@cleversolarpower You used to be able to get them but big battery systems usually used individual cells. I think lithium more or less killed off the 24V and higher lead acid batteries leaving only 12V and single cells.
I'd like to build a pure off-grid system for a cabin with a 3000w inverter. What battery and inverter brand/model would you recommend for the simplest possible system that can be purchased in Germany?
I am using Vestwoods batteries and I think they are available in Germany. Any high quality inverter will be fine. Try to get a pure sine wave inverter. They are better for your electronics.
Yes, that's true. A 12V lead-acid battery is made up of six 2V cells connected in series. Just like lithium-ion cells, these can also become imbalanced over time due to variations in capacity, internal resistance, or charge acceptance. However, lead-acid batteries have a higher internal resistance compared to lithium-ion batteries, which slows down the rate of imbalance. This slower rate of imbalance means that lead-acid batteries usually take longer to show issues, but they still require regular maintenance, such as equalization charging, to keep all cells balanced. For lithium-ion batteries, the battery management system (BMS) performs this balancing function at the cell level, but in series-configured lithium packs, imbalance between the packs themselves can still occur without proper monitoring or maintenance.
I opted for Pairing My 280ah CHINS in Series for 24 Volt Systems and Use Victron Energy Battery Balancers on all 4 Systems now. Currently Buying 24 Volt 100ah and wiring 4 in Parallel to 300 amp Buss Bars for System #5 and #6 Thank You Nick 🙌
Please, I have a question for you about 12V 100Ah LiFePO4 Batteries. If you put an amp meter on a 12V 100Ah LiFePO4 Battery terminals what would the amps meter read?
Each battery in a series string will read the same amps as all the others since the current is flowing through all the batteries in the string. Current is the same at any point in a simple circuit where the measurement encompasses all paths. The voltage across each battery is where things will vary, but with the nature of lifepo4 discharge curve they will be very similar for most of the string's discharge / charge time - until they move into the top / bottom 20% of their individual SOC.
@@floki5353 Hmm, I interpreted the question in the context of the video, series connected batteries. Maybe he was asking about short circuit, maybe not. The BMS would quickly disconnect under short circuit so his meter may not be quick enough to see the impulse correctly, or perhaps not at all. BMS reaction times to short circuits can be in the 100 usec domain.
You would need a high impedance ameter to do that. A low impedance ameter will probably draw too much power too quickly and the bms will shut down the battery. It will read 100 amp hours before the bms shuts it down.
Batteries in series do have those problems, but batteries in parallel have balancing issues too in that the ones on the outside charge more than the ones inbetween. And so the ones closest to the wired connection get more use. Also the ones that have less resistance get more charge. And as far as buying larger voltage batteries, that is a better deal if one can find a good price and availability on them. But they are not so available everywhere. Which is why I was thinking of doing 2x12 volt ones. And I could do those in parallel without the uneven charge but 3 or more would have uneven charge. I did try searching Amazon for a bms.. I didn't find one for that purpose.. maybe I could search again.
That is true. However, that is only the case if you add lots of batteries in parallel. And that's why you should use busbars in parallel battery setups.
I have been pondering this dilemma for a bit. You sold me. I shall buy 24V Batteries and Parallel them. It's also a lot easier to add another battery in parallel than to add a new string.
Correct. This is only applicable the batteries with BMSs. Lead-acid is a different beast, though depending on the lead-acid type you will still need a balancer or have to depend on an equalization schedule to keep the elements in balance, and/or other care and maintenance.
The 48v battery cost way more per Kwh so price is a contributing factor. I have 3 banks, 1-4S and 2-2S. the 4S has a balancer and the 2S banks I can wire parallel every 6 months to balance. Not as hands off as the 48v battery but really not that bad either, especially considering the extra storage I get for the trouble.
I basically agree that you should use a battery pack designed for end voltage, with overall balancing. However, there's some flaws and inaccuracies on your reasoning. By principle, having bms for each 12V set, does not provide risk. It will cut down the charge or discharge when under or over voltage is detected in any cell. However, the real risk comes from bms voltage rating. 12V bms uses switching components, designed to handle 12V system. They may be 16V, 25V, or more, but most likely not more than 30V. Your can't rely on it without specifications, and usually they are not provided. If single 12V bms try to cut out the battery in 48V system, it sees 48V across it's open fets, most likely experiencing shoot-through and melt down, which typically short circuit fets, disabling bms protection. Such system may seem to work properly, untill bms protection is needed. Then it fails. Same goes when connecting too many, so called protected 18650 cells in series. Battery packs should always be made on unprotected cells and separate protection cirquit.
What about canbus ?? connect batteries in series then together with canbus communication, the batteries balance out ?? Batteries communicating with each other
i was planing to make a small setup with 4 12v 25ah batteryes in paralel using halfway method and another same set conected in series with first one to make an 24v sistem
When you have 24/48 solar panels you have to wire in series to break fown by the charge controler snd this keep wire size smaler then. Speical when you have 3k solar panels.
eh, i dont use bms on my diy battery builds anymore. just use inductive active balancer and rely on inverter or charge controller for over/under charge protection. add a thermostat relay to the load side and hook it up to a 15w heating pad to avoid freezing temp. bms is the cause of most lithium fires. active balance boards are much cheaper, like by 2 orders of magnitude and usually have 10-100x better balance capability in terms of total current and use energy more efficiently instead of making bms get hot.
I am glad I didn't go ahead and wire four 12.8vdc Lifepo4 batteries in series. I am only focused on 48vdc to 120vac and 240vac inverters. They are the most expensive by far, but pushing the same amount of current at 12vdc vs 48vdc is a no-brainer to me, just expensive.
If you have 2V lead-acid cells you need series connections to make 12V. However, since it's much cheaper these days to get lithium, i don't know why people still get lead-acid. So this video only talks about lithium (lifepo4).
@cleversolarpower lithium batteries here are still very expensive and I don't trust them, to much electronics to run safe, I want to make a 24v system with 2v cells and only victron inverters have the right program to support them, but victron inverters are very expensive, so I need to find something else to support them (Chinese hi frequency inverters) who I don't trust them either.
I maybe the exception to the rule but I have a prismatic 12v 200ah parallel with a chins 12 v 100ah in series with 2 chins , 1 200ah and 1 100 ah in parallel and never have any issues with balance. Even the prismatic cells stay balanced without a balancer. 24volt system
Batteries in series are a well established procedure. He’s not wrong about the drift that can occur, but for $20 you can put a balancer on the batteries and resolve the problem. It’s better than spending the money on a 24 or 48 v battery when you have 12v laying around.
I agree with what you said except for the $20. balancers. I pay around $60 to $80. for my active balancers. Worth every dime though. They have an LED display that shows the voltage of every battery. If there were to be an issue I would look at the displays and quickly find the offending battery.
Buying a 24V 100Ah battery cost you $400, while two 12V 100Ah cost you $600. So it's cheaper buying one battery than connecting two in series. + you don't need a balancer and interconnecting cables. That's a no-brainer.
@@cleversolarpower I suggest you check on your prices. You might be surprised to learn you can pick up 100ah LiFePo4 batteries for as low as $139. Plenty of well reviewed choices all below $200. Mine are all connected with bus bars made from 1/2" copper tubing. Beaten flat. Drilled holes. Then coveted in heat shrink. My only complaint is space. 20 batteries take up a lot of space. It's gotten to the point where everything has to be reconfigured when I add 4 more. I'm also at the point where I think I need to get them off my back porch. Safe as they are I fear what would happen if something were to go wrong.
You have to use a battery balance system. Active flyback that takes the higher voltage and shifts it to lower performing batteries.Same battery balancer on the single battery!Kinda deceptive whe you speak! If battery balancer can work on a single battery with multiple cells,why can it not work on multiple batteries of cells?😊
Both systems are 16S. regardless if it's a 48 or 4x12. so if an element goes down, everything is gone , you're point is mute. it's all came down to balancing, either you have 1 BMS or 5 BMS's . I can continue, regarding the perfect cell match you mentioned, but I'm too lazy
I think you missed to point of this video. If you have 4x 12V batteries in series, they are not 16S. they are 4S4S. The four batteries have a separate BMS, they cannot communicate with each other. They don't see that battery one has a higher charge than the other battery. They have no way of balancing each other.
Imbalances can be solved by manually balancing all the batteries once annually, and charging all lifepo4 batteries from 0%-100%. This does not damage the battery like other lithium ion variants, and charging to 100% will get the internal BMS of each battery to balance the cells more consistently. This will keep everything balanced and long life from the batteries. Also agree with keeping same brand and aged batteries, and all line lengths should be the exact same
Manually balancing all the batteries once a year seems convenient. It could have been negated with proper design. And now you will need an additional 12V lifepo4 charger costing you $100.
@ Given the costs of everything in a solar build are easily exceeding 12k, $100 bucks to maintain the batteries life span once per year probably will save more in the long term.
Nearly all 50A or higher BMS's can handle voltages of at least 60VDC BAT+ to BAT-, so generally speaking you can connect 4 x 12.8V batteries in series, or 2 x 25.6V, or 1 x 51.2V. But even so it isn't a good idea to connect batteries with BMS's in series for a multitude of other reasons. I personally don't trust the BMSs on very small batteries like the 10, 20 and 30Ah LiFePO4's you see on Amazon to be able to run in series. But larger batteries should be fine. If battery explicitly says not to tie in series, though, then definitely don't. The tolerances are just a function of the MOSFET breakdown voltage in the BMS, 60V is actually fairly run of the mill and cheap. -Matt
Renogy’s LiFePO4 batteries were once limited in their ability to be wired in series, as their MOSFETs weren’t designed to handle 48V configurations. At the time, they could only be wired in series for 24V setups. However, Renogy has since upgraded to higher-voltage MOSFETs, eliminating this limitation. Nowadays, it’s rare to see this kind of restriction with popular battery brands.
is why you need to charge to 100% at least before getting too low, anyways I have enough panels to charge to full every day, and I have 12 batteries in 4s to 3p and soon getting 16 batteries for a total of about 53klw in 4s to 4p you have to follow the directions of manufacturers, they tell you the max you can do on series and or to parallel , if we follow that and charge to 100% regularly is not needed a balancer. I dont use balancer on my lifepo4 and manufacturer recommend only 4 in series to max 4 to parallel on the 12.8 260amp , and i been running my system over a year and not a single problem.
Like i showed in the video, it doesn't matter if you charge it to 100%, there will be imbalances. Just measure the individual battery voltage and you will see they are not the same. The manufacturer says only 4 in series because the mosfets cannot handle more voltage, and there is no use to have more in series because you already have 48V.
You sre perfectly correct in theory but real life starting out with two new 12.8V-100Ah LiFePO4 as example. Fully charge both batteries to chager stop charging. I will claim your scenario will not happen unless one cell get a problem.
Still, that doesn't mean you should wire in series just because they can 😉. I can use a 5000W inverter with a 12V lead-acid battery, but that doesn't mean i should.
I rather not check the voltage of my battery. And you need a 12V lifepo4 charger for that. An additional headache. It's way better to get a higher voltage battery. No check, no headaches and no worries.
Will Prowse commented on this a while back. His experience was balancers are not needed with lithium . If someone was concerned they should balance after six months or more.
@@cleversolarpower Because in here in the US, you can get 4x 100ah 12v batteries for $600 vs buying a 48v 100ah that cost $1000. Plus most people start off doing 12v systems. Gradually they move up and once you move up, it's natural to put those old 12v to good use. Not a lot of people start doing solar just go straight to 48v.
Most users will simply be oblivious to the issue until they try to pull full capacity from their battery when the weather is bad and then the lights go out. Decent lithium manufacturer's do state the requirement to separately charge the batteries at least every few months or to charge the batteries with a separate floating charger on each individual battery. Personally I don't want to be turning my system off every 6 months to separate the batteries and fully charge. Not only is it time consuming and I must have an alternate power source while I am doing it, it puts repeated stress on the battery terminals (threaded type which is pretty common) and they will eventually tear out even when torqued properly.
@@Firephosureno knowledge that’s why people start off with 12V…my first system I went 24V & I’m in the U.S of A 😩 don’t comment for the entire country please 😞
@@CampedOutGamers Learn to read. My first comment is for the price pertaining to the price difference buying 12v vs 48v in the USA. Second comment is "most" people. I didn't say ALL. Just because you started out at 24v doesn't mean most.
Slightly misleading title since this applies to Lithium based 12V batteries - combining 12V Lead Acid batteries in series has been done for decades if I'm not mistaken albeit they need to be carefully looked after. Also, I was under the impression that the single 48V Lithium-based packs are actually 15 cells in series since the nominal 3.2V/cell x15 = 48V - they charge at around 3.5V per cell and hence internal balancing isn't an issue - plus if one cell goes bad you're not having to replace an entire pack - there are pros and cons to having more hardware...
Yes, i'm talking about lifepo4 batteries. Who uses lead-acid these days? You are saying 'they need to be carefully looked after' that is the reason i made this video. Most 48V lifepo4 batteries are 16S, very few are 15S. If a battery in a parallel setup goes bad, nothing bad happens, you have reduced capacity. But if a battery in a series string goes bad, the whole battery is out of order.
I wondered about exactly this. Even with lead acid batteries, in commercial vehicles, rvs, boats etc, wired for 24v, people manage to get the batteries out of balance and struggle with starting/charging issues. With solar systems in domestic situations, the opportunities for problems always seemed more plentiful, albeit mitigated by the fact that domestic installations are more closely regulated and rarely dealt with by diy-ers. In the marine and leisure vehicle industry, I always try to keep 24v circuits to a minimum. If at all possible, I use 12v for everything. You have to use heavier cables, particularly for big loads, like starting, but you eliminate a potential source of recurring trouble. I’ve seen a battery in a 24v starter bank explode, due to being out of balance. With my own 24v systems, I occasionally disconnect them and wire them in parallel to a 12v smart charger, to keep them in balance. I suspect this would be helpful in the examples given here, too. This problem is going to become more common, because 12v LiFePO4 batteries are much cheaper and easier to get hold of than their higher voltage counterparts. People ARE going to be wiring them in series, because the budget dictates it. They need to be educated about keeping such systems alive. Ideally, the BMS in each battery would be able to communicate with other BMSes in the string, but that facility would add expense, so probably not gonna happen. That being so, manual balancing on a scheduled maintenance plan would probably be a good idea.
1:04 This expert does not understand batteries enough to be an expert. If one wants to configure a 72volts(nominal) power pack out of 6 units of 12volts(nominal) batteries, one may 1)open each battery, 2)disconnect the 12volts BMS from each of them, and 3)connect the string of 24 cells to a properly rated 72volts BMS(if he can find one). Or, he may connect the 6 batteries in parallel and use a DCtoDC converter to get the desired voltage.
Don't think you understand what nick is saying in this video. If you have single cell batteries and run them in series no problem but with multiple bms's problem occurs, not communicating with each other.
Lithium batteries need to be within 0.2 volts before connecting in series. Lithium batteries will balance themselves. Learn what your preaching before commenting.
No, lithium batteries need to be fully charged before connecting in series. Because their soc can vary greatly, even at a 0.2V difference. Lithium batteries only balance themselves in parallel, not in series.
2 x redodo 100Ah have a in multi review measured capacity of 104 ah they are all in this range with 1% proven scatter in production. so how your conspiracy theorie works with 30% differenz? you get 1 redodo 100Ah with 104 Ah inside and the other redodo 100 Ah has 70 Ah capacitiy? my oldest LiFePo4 is now 10 years old and after this time it still have 95% of there rated capacity so LiFePo4 have over time no capacity use in real world use. so how you com on this 2 different capacitys??? to ake video and show comlete unlogic stuff brings you what?
Not sure about your question, but here it goes: In a series connection batteries need to have the same capacity. If one battery has higher capacity than a series connection is not suitable. That's why i recommend wiring in parallel.
@cleversolarpower jeżeli chodziło by o same okablowanie to po co robić taki materiał, rozumiem że brak ci pomysłów tym bardziej że przestrzegasz przed łączeniem baterii szeregowo, tymczasem 75% banków energii jakie znam powyżej 25 KWh są właśnie tak łączone, nawet elektronarzędzia z dwoma bateriami mają połączone baterie w sposób który uważasz za błędny. Nie przygotowałeś się poprostu
@brianOcurradhin jeżeli nie jest dla ciebie oczywistym, by sięgnąć po powszechną wiedzę, zwłaszcza gdy masz do czynienia z urządzeniami mogącymi zagrozić życiu i zdrowiu to sam jesteś ignorantem bronisz idiotów twojego pokroju. Jestem przeciwny publikacji bezwartościowych materiałów które są powtórkami bardzo niskiej jakości ponadto utrudniają dostęp do wartościowych materiałów znajdujących się na tej platformie.
"Exact matching required." Not really: if the batteries were actually perfectly matched, you wouldn't need a balancer in the first place. We need BMS and balancers specifically because it is impossible to perfectly match cells since even perfectly factory-matched cells will drift differently over time due to slight variations in local parameters like heat exposure, airflow, uneven compression, etc. Having better-matched batteries only reduces the amount of balancing work required.
@@cleversolarpower How poorly matched your cells can be is determined by how much total capacity you are willing to sacrifice and how much additional management effort you are willing to put into it. With enough determination, you could make an SLA+NiCd+NiMH+NMC+NCA+LTO+LFP+LiS series monstrosity work. While you shouldn't intentionally mismatch batteries in a new system, you have to work with whatever you've got afterwards and there is a lot more flexibility in there than exactness.
If that happens than you can still run your inverter and charger controller. A battery with less capacity (ah), doesn't change the system. If a series connection fails, then your inverter, charge controller, and your whole system is out of order because it's not the voltage they supposed to work on.
@cleversolarpower this is a great point for anyone running 12v at low amps with large enough wires for the extra load but I prefer the efficiency gain in 24v over 12 and some inverters are dual voltage. Personally I also have in place a 24v to 12v converter and know how to easily create a coil should I need more voltage from 12v. But yes. All good points.
open those single batteries up and you will find batteries in series.... All batteries are in series ..... They all just need to be balanced once in a while stop the BS...
Did you miss the video entirely? The cells are balanced by the BMS of the battery. It's more batteries in series that's the problem because they cannot see each other. It's 30 seconds in the video 😄
@cleversolarpower is why you need to charge to 100% at least before getting too low, anyways I have enough panels to charge to full every day, and I have 12 batteries in 4s to 3p and soon getting 16 batteries, you have to follow the directions of manufacturers, they tell you the max you can do on series and to parallel , if we follow that and charge to 100% regularly is not needed an balancer.
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What about in PARALLEL???
I worked for British Telecom for many years. The telephone exchanges had battery backups and a diesel generator. Each battery was 6v lead-acid, and wired in series. Because of imbalances, but it was an acceptable problem / consequence, we had to change the batteries often, and certainly more regularly than you'd expect. You're absolutely correct, but most people will be happy to wire two 12v in series. 😉
Yes, and a backup station is not made to cycle all day, so i expect the imbalances to be less visible. This video doesn't really focus on lead-acid. Maybe i should have talked a bit more about lead-acid.
@cleversolarpower Sorry, I didn't explain too well. The batteries were always used. Mainly to smooth out the feed and ensure a steady DC supply. They were mains charged, but generator during a power cut.
So the batteries were in continuous use.
@floki5353 To be honest, I'm unsure. Nowadays, yes. Back when they were the strowger sets, I don't think there was unless you count the huge capacitors?
Lead acid in series is a bit easier. That chemistry tolerates overcharge which it dissipates as heat as vaporizing electrolyte. This allows the series string to be periodically "equalized" to a higher charge voltage which ensures all series cells are fully charged. Electrolyte management is a separate issue. After using lead for years, running LiFePO4 is almost magic.
What about battery equalization function of Charge Controller which is programmed to run every month or week?
Completely agree with you on this, and this is something I've long stated. SOC divergence can be seen on maintenance free lead acid systems too and they need an external balancer to keep them in check. Open cell wet lead acid allows one to simply over charge each cell to bring the batteries up to the same SOC and then replace lost electrolyte.
Good to see someone agree on this matter. Other commenters try to justify their series connection 😅
This guy knows more about this stuff in his little finger than most people and is genuine, download the diagrams he has they're free
People have been connecting batteries in series for years without issues especially those that use balancers. Some people actually started out with a small 12v system and later realized they want to move to higher voltage without discarding their already bought batteries. This is why many people usually series their batteries.
I recommend watching the video again and paying attention to the section about balancers 😉
lmao! The guy is a retard lol.
Hahahahahaha
I though power goes up even if they are connected in parallel
I have a 12V system and use agm sla batteries wired in parallel. I routinely disconnect and test each battery individually so as not to get any false feedback from the testing. I have not had any problems as yet, and everything seems to be in good working order and balanced.
You said your batteries are in parallel, so you don't have to worry about imbalances. It's only a problem with series connections.
@cleversolarpower , I have been told that if you have one battery that won't hold charge, it can drain your other batteries that it's connected to, and if left connected to the other batteries, can damage them. I don't know if that's true, but it does sound plausible. So I err on the side of caution and test my batteries on a regular basis.
So asuming i have a full 24v battery in parallel and i want ti upgrade to 48v will i add another 24 volts in parallel or i should buy single 48v and remove thr 24v?
Got your book, great job. Also awesome vids.
Thanks for your support!
Thanks.
Please Sir, does this also apply to flooded lead acid batteries? Due to cost implications, I and most people are using lead acid batteries in my area.
I made this video for lithium. For lead acid, you also require a balancer but harder to find 24V or even 48V deep cycle batteries.
I'd like you to make video for lead acid batteries. The effects of its series and parallel connections.
Open cell flooded does drift in a similar way but you have the option of simply over charging the batteries to bring all cells up to full charge and periodically replacing lost water. You can't do this with maintenance free batteries since over charging there for flooded cells will see loss of electrolyte over time; AGM and gel types will be damaged by over charging.
This used to be a problem for me with my acid batteries. But now that I can log into each battery individually and monitor it through its Bluetooth BMS I can see that they are staying well-balanced. It seems that if they were to get out of BALANCE the one that had the higher voltage would have an automatic cut off when it reached a voltage too high.
Your speaking is so nice
@cleversolarpower One question please, I have already bought 3 12v 150A lifepo4 batteries, the idea was to buy a 4th battery to be able to achieve a 12, 24, or 48 configuration. Watching your video it makes a lot of sense, now my question is the following, do you recommend me to finish my 12v string connected in parallel, or make a 2P2S to make a 24v system?
You can still finish your system. I recommend watching how they behave (measure the voltages of each battery) and add a balancer if needed. You will need one over time anyway.
Same for SLA??
No, this video is only for lithium (lifepo4). There are no 24 or 48V SLA batteries available as far as i know. But why would you use SLA batteries anyway?
@@cleversolarpowerbecause they are EMP apocalypse proof.
@@cleversolarpower You used to be able to get them but big battery systems usually used individual cells. I think lithium more or less killed off the 24V and higher lead acid batteries leaving only 12V and single cells.
@@cleversolarpower Lower cost, hazard. Greater temperature resilience.
I'd like to build a pure off-grid system for a cabin with a 3000w inverter. What battery and inverter brand/model would you recommend for the simplest possible system that can be purchased in Germany?
I recommend the victron multiplus. Checkout my playlist about 'off grid systems' there is one in there for a cabin.
I am using Vestwoods batteries and I think they are available in Germany.
Any high quality inverter will be fine. Try to get a pure sine wave inverter. They are better for your electronics.
what about wiring lead acid batteries in series?
You also need a balancer.
I'm glad I'm going with parallel configuration
Awesome dude.
Many UPS systems use serial connection without balancing
Yes, that's true. A 12V lead-acid battery is made up of six 2V cells connected in series. Just like lithium-ion cells, these can also become imbalanced over time due to variations in capacity, internal resistance, or charge acceptance. However, lead-acid batteries have a higher internal resistance compared to lithium-ion batteries, which slows down the rate of imbalance.
This slower rate of imbalance means that lead-acid batteries usually take longer to show issues, but they still require regular maintenance, such as equalization charging, to keep all cells balanced. For lithium-ion batteries, the battery management system (BMS) performs this balancing function at the cell level, but in series-configured lithium packs, imbalance between the packs themselves can still occur without proper monitoring or maintenance.
Those are SLA batteries.
I opted for Pairing My 280ah CHINS in Series for 24 Volt Systems and Use Victron Energy Battery Balancers on all 4 Systems now.
Currently Buying 24 Volt 100ah and wiring 4 in Parallel to 300 amp Buss Bars for System #5 and #6
Thank You Nick 🙌
Yes, adding a 24V battery in parallel with your 2x12V batteries in series is no problem as well.
Please, I have a question for you about 12V 100Ah LiFePO4 Batteries. If you put an amp meter on a 12V 100Ah LiFePO4 Battery terminals what would the amps meter read?
Each battery in a series string will read the same amps as all the others since the current is flowing through all the batteries in the string. Current is the same at any point in a simple circuit where the measurement encompasses all paths. The voltage across each battery is where things will vary, but with the nature of lifepo4 discharge curve they will be very similar for most of the string's discharge / charge time - until they move into the top / bottom 20% of their individual SOC.
@@floki5353 Hmm, I interpreted the question in the context of the video, series connected batteries. Maybe he was asking about short circuit, maybe not. The BMS would quickly disconnect under short circuit so his meter may not be quick enough to see the impulse correctly, or perhaps not at all. BMS reaction times to short circuits can be in the 100 usec domain.
You would need a high impedance ameter to do that. A low impedance ameter will probably draw too much power too quickly and the bms will shut down the battery. It will read 100 amp hours before the bms shuts it down.
Batteries in series do have those problems, but batteries in parallel have balancing issues too in that the ones on the outside charge more than the ones inbetween. And so the ones closest to the wired connection get more use. Also the ones that have less resistance get more charge.
And as far as buying larger voltage batteries, that is a better deal if one can find a good price and availability on them. But they are not so available everywhere. Which is why I was thinking of doing 2x12 volt ones. And I could do those in parallel without the uneven charge but 3 or more would have uneven charge.
I did try searching Amazon for a bms.. I didn't find one for that purpose.. maybe I could search again.
That is true. However, that is only the case if you add lots of batteries in parallel. And that's why you should use busbars in parallel battery setups.
@@cleversolarpower Depending how they are wired.. 3 would make it uneven..even with busbars.. The ones closest to the connection get more use.
Does anyone have any experience with connecting batteries using JK Bms's in series or in parallel? Would be very interested to hear how it went.
No problem.
I have been pondering this dilemma for a bit.
You sold me.
I shall buy 24V Batteries and Parallel them. It's also a lot easier to add another battery in parallel than to add a new string.
Exactly 💯
@@cleversolarpower Yeah, it strikes me that the 24V Batteries are the best Medium between affordability and capacity, with the least effort to add.
this is only the case for lithium ion batteries right? in my country we use 6v batteries in series parallel connections for massive battery banks.
Correct. This is only applicable the batteries with BMSs. Lead-acid is a different beast, though depending on the lead-acid type you will still need a balancer or have to depend on an equalization schedule to keep the elements in balance, and/or other care and maintenance.
The 48v battery cost way more per Kwh so price is a contributing factor. I have 3 banks, 1-4S and 2-2S. the 4S has a balancer and the 2S banks I can wire parallel every 6 months to balance. Not as hands off as the 48v battery but really not that bad either, especially considering the extra storage I get for the trouble.
I basically agree that you should use a battery pack designed for end voltage, with overall balancing. However, there's some flaws and inaccuracies on your reasoning.
By principle, having bms for each 12V set, does not provide risk. It will cut down the charge or discharge when under or over voltage is detected in any cell. However, the real risk comes from bms voltage rating. 12V bms uses switching components, designed to handle 12V system. They may be 16V, 25V, or more, but most likely not more than 30V. Your can't rely on it without specifications, and usually they are not provided.
If single 12V bms try to cut out the battery in 48V system, it sees 48V across it's open fets, most likely experiencing shoot-through and melt down, which typically short circuit fets, disabling bms protection. Such system may seem to work properly, untill bms protection is needed. Then it fails.
Same goes when connecting too many, so called protected 18650 cells in series. Battery packs should always be made on unprotected cells and separate protection cirquit.
Nowadays BMS'es are rated for 48V, before this wasn't the case. They will tell you how many batteries you can wire in series.
What about canbus ?? connect batteries in series then together with canbus communication, the batteries balance out ?? Batteries communicating with each other
Canbus wires cannot carry a current; they are only used for signal transmission. You need a balancer between the batteries.
i was planing to make a small setup with 4 12v 25ah batteryes in paralel using halfway method and another same set conected in series with first one to make an 24v sistem
Just buy one 24V 100Ah battery, much cheaper and better.
When you have 24/48 solar panels you have to wire in series to break fown by the charge controler snd this keep wire size smaler then. Speical when you have 3k solar panels.
Just buy individual cells and bms.
I would never buy 48V 100 Ah battery. It is too big and to heavy.
Some people are not comfortable or have time to make their own battery.
4S BMS - 12.8V nominal
8S BMS - 25.6V nominal
16S BMS - 51.2V nominal
eh, i dont use bms on my diy battery builds anymore. just use inductive active balancer and rely on inverter or charge controller for over/under charge protection. add a thermostat relay to the load side and hook it up to a 15w heating pad to avoid freezing temp. bms is the cause of most lithium fires. active balance boards are much cheaper, like by 2 orders of magnitude and usually have 10-100x better balance capability in terms of total current and use energy more efficiently instead of making bms get hot.
I am glad I didn't go ahead and wire four 12.8vdc Lifepo4 batteries in series. I am only focused on 48vdc to 120vac and 240vac inverters. They are the most expensive by far, but pushing the same amount of current at 12vdc vs 48vdc is a no-brainer to me, just expensive.
Exactly, for higher power systems use 48V. I recommend using 48V systems if your inverter is 3000W or higher.
Led acid batteries work's better with balancers even with different capacities, for 2v cells i can't find balancers.
If you have 2V lead-acid cells you need series connections to make 12V. However, since it's much cheaper these days to get lithium, i don't know why people still get lead-acid. So this video only talks about lithium (lifepo4).
@cleversolarpower lithium batteries here are still very expensive and I don't trust them, to much electronics to run safe, I want to make a 24v system with 2v cells and only victron inverters have the right program to support them, but victron inverters are very expensive, so I need to find something else to support them (Chinese hi frequency inverters) who I don't trust them either.
I maybe the exception to the rule but I have a prismatic 12v 200ah parallel with a chins 12 v 100ah in series with 2 chins , 1 200ah and 1 100 ah in parallel and never have any issues with balance. Even the prismatic cells stay balanced without a balancer. 24volt system
A chins battery already has a BMS with balancer inside, and since you have them connected in parallel there is no unbalance.
Batteries in series are a well established procedure. He’s not wrong about the drift that can occur, but for $20 you can put a balancer on the batteries and resolve the problem. It’s better than spending the money on a 24 or 48 v battery when you have 12v laying around.
I agree with what you said except for the $20. balancers. I pay around $60 to $80. for my active balancers. Worth every dime though. They have an LED display that shows the voltage of every battery. If there were to be an issue I would look at the displays and quickly find the offending battery.
Buying a 24V 100Ah battery cost you $400, while two 12V 100Ah cost you $600. So it's cheaper buying one battery than connecting two in series. + you don't need a balancer and interconnecting cables. That's a no-brainer.
@@cleversolarpower I suggest you check on your prices. You might be surprised to learn you can pick up 100ah LiFePo4 batteries for as low as $139. Plenty of well reviewed choices all below $200. Mine are all connected with bus bars made from 1/2" copper tubing. Beaten flat. Drilled holes. Then coveted in heat shrink. My only complaint is space. 20 batteries take up a lot of space. It's gotten to the point where everything has to be reconfigured when I add 4 more. I'm also at the point where I think I need to get them off my back porch. Safe as they are I fear what would happen if something were to go wrong.
You have to use a battery balance system. Active flyback that takes the higher voltage and shifts it to lower performing batteries.Same battery balancer on the single battery!Kinda deceptive whe you speak! If battery balancer can work on a single battery with multiple cells,why can it not work on multiple batteries of cells?😊
LiFePO4 discharge curve is very flat so battery balancer dont do the same job as in lead acid case
Both systems are 16S. regardless if it's a 48 or 4x12. so if an element goes down, everything is gone , you're point is mute. it's all came down to balancing, either you have 1 BMS or 5 BMS's . I can continue, regarding the perfect cell match you mentioned, but I'm too lazy
I think you missed to point of this video. If you have 4x 12V batteries in series, they are not 16S. they are 4S4S. The four batteries have a separate BMS, they cannot communicate with each other. They don't see that battery one has a higher charge than the other battery. They have no way of balancing each other.
Imbalances can be solved by manually balancing all the batteries once annually, and charging all lifepo4 batteries from 0%-100%. This does not damage the battery like other lithium ion variants, and charging to 100% will get the internal BMS of each battery to balance the cells more consistently. This will keep everything balanced and long life from the batteries. Also agree with keeping same brand and aged batteries, and all line lengths should be the exact same
Manually balancing all the batteries once a year seems convenient. It could have been negated with proper design. And now you will need an additional 12V lifepo4 charger costing you $100.
@ Given the costs of everything in a solar build are easily exceeding 12k, $100 bucks to maintain the batteries life span once per year probably will save more in the long term.
I had that exact problem when i connected the batteries in Series for 24 volts. The batteries would not stay balanced
Both new same type and model? LiFePO4 type?
@@boapvdk Valence U27 12XP Not new
Every car battery has 6 cells in series. Trucks have usually 2 batteries in series, e.g. 24V
Yes, they are lead acid.
i always thought for lithium batteries that this was not a good idea / impossible because the bms could not handle the higher total voltage.
Nearly all 50A or higher BMS's can handle voltages of at least 60VDC BAT+ to BAT-, so generally speaking you can connect 4 x 12.8V batteries in series, or 2 x 25.6V, or 1 x 51.2V. But even so it isn't a good idea to connect batteries with BMS's in series for a multitude of other reasons.
I personally don't trust the BMSs on very small batteries like the 10, 20 and 30Ah LiFePO4's you see on Amazon to be able to run in series. But larger batteries should be fine. If battery explicitly says not to tie in series, though, then definitely don't.
The tolerances are just a function of the MOSFET breakdown voltage in the BMS, 60V is actually fairly run of the mill and cheap.
-Matt
Renogy’s LiFePO4 batteries were once limited in their ability to be wired in series, as their MOSFETs weren’t designed to handle 48V configurations. At the time, they could only be wired in series for 24V setups. However, Renogy has since upgraded to higher-voltage MOSFETs, eliminating this limitation. Nowadays, it’s rare to see this kind of restriction with popular battery brands.
cool
This is a problem for lead acid as well.
Indeed.
is why you need to charge to 100% at least before getting too low, anyways I have enough panels to charge to full every day, and I have 12 batteries in 4s to 3p and soon getting 16 batteries for a total of about 53klw in 4s to 4p you have to follow the directions of manufacturers, they tell you the max you can do on series and or to parallel , if we follow that and charge to 100% regularly is not needed a balancer.
I dont use balancer on my lifepo4 and manufacturer recommend only 4 in series to max 4 to parallel on the 12.8 260amp , and i been running my system over a year and not a single problem.
Like i showed in the video, it doesn't matter if you charge it to 100%, there will be imbalances. Just measure the individual battery voltage and you will see they are not the same. The manufacturer says only 4 in series because the mosfets cannot handle more voltage, and there is no use to have more in series because you already have 48V.
@cleversolarpower ok i will check them individually and we see , if too much difference i will install a balancer.
You sre perfectly correct in theory but real life starting out with two new 12.8V-100Ah LiFePO4 as example. Fully charge both batteries to chager stop charging. I will claim your scenario will not happen unless one cell get a problem.
Ok, just do what you described, and measure the voltages of your batteries after a few months. You will see they will be different.
All batteries are made from low voltage cells connected in series. 6 at 2.2v to make a 12v lead acid. Never been an issue.
Most battery manufacturers state what configuration the battery can be used. E.g. 4S4P, 2S1P etc
Still, that doesn't mean you should wire in series just because they can 😉. I can use a 5000W inverter with a 12V lead-acid battery, but that doesn't mean i should.
Why would you use a 12 lithium battery in a solar system? A string of 4.2v blade cells in series with a decent BMS will be a lot more efficient.
If you have a small system and use 12V loads or are in a van, 12V is a good choice.
I have 1000w in invirter 50hz
Check and top off the individual banks twice a year and you will be fine.
I rather not check the voltage of my battery. And you need a 12V lifepo4 charger for that. An additional headache. It's way better to get a higher voltage battery. No check, no headaches and no worries.
Will Prowse commented on this a while back. His experience was balancers are not needed with lithium . If someone was concerned they should balance after six months or more.
If you have to balance after 6 months, it's still a bad design. Why not use a higher voltage and not have to worry about it?
@@cleversolarpower Because in here in the US, you can get 4x 100ah 12v batteries for $600 vs buying a 48v 100ah that cost $1000. Plus most people start off doing 12v systems. Gradually they move up and once you move up, it's natural to put those old 12v to good use. Not a lot of people start doing solar just go straight to 48v.
Most users will simply be oblivious to the issue until they try to pull full capacity from their battery when the weather is bad and then the lights go out. Decent lithium manufacturer's do state the requirement to separately charge the batteries at least every few months or to charge the batteries with a separate floating charger on each individual battery. Personally I don't want to be turning my system off every 6 months to separate the batteries and fully charge. Not only is it time consuming and I must have an alternate power source while I am doing it, it puts repeated stress on the battery terminals (threaded type which is pretty common) and they will eventually tear out even when torqued properly.
@@Firephosureno knowledge that’s why people start off with 12V…my first system I went 24V & I’m in the U.S of A 😩 don’t comment for the entire country please 😞
@@CampedOutGamers Learn to read. My first comment is for the price pertaining to the price difference buying 12v vs 48v in the USA. Second comment is "most" people. I didn't say ALL. Just because you started out at 24v doesn't mean most.
Slightly misleading title since this applies to Lithium based 12V batteries - combining 12V Lead Acid batteries in series has been done for decades if I'm not mistaken albeit they need to be carefully looked after. Also, I was under the impression that the single 48V Lithium-based packs are actually 15 cells in series since the nominal 3.2V/cell x15 = 48V - they charge at around 3.5V per cell and hence internal balancing isn't an issue - plus if one cell goes bad you're not having to replace an entire pack - there are pros and cons to having more hardware...
Yes, i'm talking about lifepo4 batteries. Who uses lead-acid these days? You are saying 'they need to be carefully looked after' that is the reason i made this video. Most 48V lifepo4 batteries are 16S, very few are 15S. If a battery in a parallel setup goes bad, nothing bad happens, you have reduced capacity. But if a battery in a series string goes bad, the whole battery is out of order.
I wondered about exactly this.
Even with lead acid batteries, in commercial vehicles, rvs, boats etc, wired for 24v, people manage to get the batteries out of balance and struggle with starting/charging issues.
With solar systems in domestic situations, the opportunities for problems always seemed more plentiful, albeit mitigated by the fact that domestic installations are more closely regulated and rarely dealt with by diy-ers.
In the marine and leisure vehicle industry, I always try to keep 24v circuits to a minimum. If at all possible, I use 12v for everything. You have to use heavier cables, particularly for big loads, like starting, but you eliminate a potential source of recurring trouble.
I’ve seen a battery in a 24v starter bank explode, due to being out of balance.
With my own 24v systems, I occasionally disconnect them and wire them in parallel to a 12v smart charger, to keep them in balance.
I suspect this would be helpful in the examples given here, too. This problem is going to become more common, because 12v LiFePO4 batteries are much cheaper and easier to get hold of than their higher voltage counterparts. People ARE going to be wiring them in series, because the budget dictates it. They need to be educated about keeping such systems alive. Ideally, the BMS in each battery would be able to communicate with other BMSes in the string, but that facility would add expense, so probably not gonna happen.
That being so, manual balancing on a scheduled maintenance plan would probably be a good idea.
1:04 This expert does not understand batteries enough to be an expert. If one wants to configure a 72volts(nominal) power pack out of 6 units of 12volts(nominal) batteries, one may 1)open each battery, 2)disconnect the 12volts BMS from each of them, and 3)connect the string of 24 cells to a properly rated 72volts BMS(if he can find one).
Or, he may connect the 6 batteries in parallel and use a DCtoDC converter to get the desired voltage.
You must be trolling right? 😄
Nonsense! Charge series wired batteries separately and use a diode harness to connect them, in case of single battery failure. Job done.
Doesn't charging each 12v battery separately introduce more complexity though?
@@malk6277 Such as ?
@@Humanity101-zp4sq In what manner were you proposing to charge them separately?
@@malk6277 Through the bms, like any other charge process!
@@floki5353 One 12v charger would suffice, with switchover relays if the installation is permanent.
Oh it's easy to run batteries in series without any issues, do a bit more research
I think you missed the point of this video.
Don't think you understand what nick is saying in this video. If you have single cell batteries and run them in series no problem but with multiple bms's problem occurs, not communicating with each other.
A12v bms would disagree.
@@zummerzetwoodsman1067 maybe he shouldn't have such a dumb title for the video?
This only applies to lithium batteries
i use two 12v 200ah lifepo4 in series,never had a issue.i use the victron battery balancer and works fine.
If you got a 24V 100Ah battery and put it in parallel with another one, you didn't need a balancer, all the extra wiring and the headache.
Just your opinion. Pity it’s mainly electronically wrong.
Please let us know how this reasoning is wrong. We all want to learn.
@jimjasper9851 it's science your just wrong!
You clearly haven't used the system enough
Are you saying that batteries in series is a good idea?
Lol clueless UA-cam makes it easy for everyone to be a teacher lol
Please let us know what's wrong so we can all learn from you.
@chuk Your hating and your wrong just another troll
Lithium batteries need to be within 0.2 volts before connecting in series. Lithium batteries will balance themselves. Learn what your preaching before commenting.
No, lithium batteries need to be fully charged before connecting in series. Because their soc can vary greatly, even at a 0.2V difference. Lithium batteries only balance themselves in parallel, not in series.
@davemac521 you don't know what your talking about
2 x redodo 100Ah have a in multi review measured capacity of 104 ah they are all in this range with 1% proven scatter in production.
so how your conspiracy theorie works with 30% differenz?
you get 1 redodo 100Ah with 104 Ah inside
and the other redodo 100 Ah has 70 Ah capacitiy?
my oldest LiFePo4 is now 10 years old and after this time it still have 95% of there rated capacity so LiFePo4 have over time no capacity use in real world use.
so how you com on this 2 different capacitys???
to ake video and show comlete unlogic stuff brings you what?
Not sure about your question, but here it goes: In a series connection batteries need to have the same capacity. If one battery has higher capacity than a series connection is not suitable. That's why i recommend wiring in parallel.
To o czym mówisz zawsze bierze się pod uwagę budując Bank energii, żadne odkrycie zresztą mówisz o tym o dwie dekady za późno.
Did you miss the part where I said it's much more wiring and more complicated?
@cleversolarpower jeżeli chodziło by o same okablowanie to po co robić taki materiał, rozumiem że brak ci pomysłów tym bardziej że przestrzegasz przed łączeniem baterii szeregowo, tymczasem 75% banków energii jakie znam powyżej 25 KWh są właśnie tak łączone, nawet elektronarzędzia z dwoma bateriami mają połączone baterie w sposób który uważasz za błędny. Nie przygotowałeś się poprostu
Everybody's a true genius showing your ignorance @phredka
@brianOcurradhin jeżeli nie jest dla ciebie oczywistym, by sięgnąć po powszechną wiedzę, zwłaszcza gdy masz do czynienia z urządzeniami mogącymi zagrozić życiu i zdrowiu to sam jesteś ignorantem bronisz idiotów twojego pokroju. Jestem przeciwny publikacji bezwartościowych materiałów które są powtórkami bardzo niskiej jakości ponadto utrudniają dostęp do wartościowych materiałów znajdujących się na tej platformie.
"Exact matching required." Not really: if the batteries were actually perfectly matched, you wouldn't need a balancer in the first place. We need BMS and balancers specifically because it is impossible to perfectly match cells since even perfectly factory-matched cells will drift differently over time due to slight variations in local parameters like heat exposure, airflow, uneven compression, etc.
Having better-matched batteries only reduces the amount of balancing work required.
I was referring to the capacity (ah), not internal resistance 😉
@@cleversolarpower How poorly matched your cells can be is determined by how much total capacity you are willing to sacrifice and how much additional management effort you are willing to put into it. With enough determination, you could make an SLA+NiCd+NiMH+NMC+NCA+LTO+LFP+LiS series monstrosity work.
While you shouldn't intentionally mismatch batteries in a new system, you have to work with whatever you've got afterwards and there is a lot more flexibility in there than exactness.
It's too big a step financially for some of us I'm afraid. We learn as we go though😊
A 24V 100Ah battery cost $400. Two 12V 100Ah batteries cost $600. They have the same capacity.
This is nonsense, most battery-operated batteries have batteries in series. Clearly misunderstanding the pocess
Have you watched the video? 😄
@@cleversolarpower Yes and you use terms you do not understand not to mention the click bait title
@ProfessorDIY ironically you are no professional
@@Fatfreddy7 Are you? I do not need to be a professional to know basic electrical theory which I do
you need to go back to school to learn physics. bunch of bs in this video
Please let us know what's wrong with this video so we can learn from your wisdom.
BS!!!!!!
Why?
You can connect batteries in series, never a problem. Bin doing that for 50 years. How else are you going to get 120 V DC!
This video is geared towards lifepo4. If you have lead-acid you either need equalization or balancers as well.
@robertkat you people don't listen, lifepo4
If you run parallel batteries and one of them is bad you have the same issue except with amp hours instead of voltage so 😮
If that happens than you can still run your inverter and charger controller. A battery with less capacity (ah), doesn't change the system. If a series connection fails, then your inverter, charge controller, and your whole system is out of order because it's not the voltage they supposed to work on.
@cleversolarpower this is a great point for anyone running 12v at low amps with large enough wires for the extra load but I prefer the efficiency gain in 24v over 12 and some inverters are dual voltage. Personally I also have in place a 24v to 12v converter and know how to easily create a coil should I need more voltage from 12v. But yes. All good points.
open those single batteries up and you will find batteries in series....
All batteries are in series ..... They all just need to be balanced once in a while stop the BS...
Did you miss the video entirely? The cells are balanced by the BMS of the battery. It's more batteries in series that's the problem because they cannot see each other. It's 30 seconds in the video 😄
@cleversolarpower is why you need to charge to 100% at least before getting too low, anyways I have enough panels to charge to full every day, and I have 12 batteries in 4s to 3p and soon getting 16 batteries, you have to follow the directions of manufacturers, they tell you the max you can do on series and to parallel , if we follow that and charge to 100% regularly is not needed an balancer.
Manufacturers state they can be added in series as long as all batteries are balanced before hand?
Yes, but over time an unbalance will develop. Depending on how hard you cycle them.
@ thank you for the reply. I am going to be switching from 2x lead batteries in series to 2x lithium batteries so I will go down the parrallel route.