Lifepo4 Top Balancing Mistake - How to build a 48v Lifepo4 battery
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- Опубліковано 3 лип 2024
- Today I unpack All of the individual battery cells connect them up in parallel and then try to top balance the cells but I learned something interesting.
I got the battery cells from Shenzhen Qishou Technology Limited
qsolifepo4cell.en.alibaba.com/
I've had 2 lots from them so far and they've been absolutely brilliant.
The battery case I got from eelbattery.myshopify.com/
I wish people who don't know what they are doing wouldn't make tutorial videos.
Agree. Also. Safety first. Using non protected tools in metal. No safety glasses…. This video need to be labelles as : how to make a short” please also you can use a 40a charging that. This one.
Yea like bro, stop please, I can't watch this. Top balance voltage is 3.65. And you check every cel before connecting them in parallel.
Remove jewellery when working on batteries. Also connect the leads at opposite ends of the pack
I was about to suggest the same thing. It's important to connect each lead at opposite ends of the pack to make sure that you have similar resistance to each cell. When you connect at one end only, the cells near the connections have less resistance between them and the power supply than the ones at the other end of the pack.
Always wear safety glasses as well. Put heat shrink over the handles of the tools so can't accidently short out. When you bolt all those together almost 5000 amps.
You want to watch your back mate lifting that kind of weight off the floor. Keep your back straight and bend the knees
even with opposite i would still add more same lenght cables or another paralel charger or dc to dc charger same voltage similar amperage to more busbars... those are masive and many people off grid strugle to fiind correct methods...
It is important to check each individiual cell before you connect them, if a cell would had been discharged because of some internal short, the other cells could have cooked it.....
3.2v is the nominal voltage. They need to be charged to 3.65V to top balance. Do NOT touch the amperage once you start. Set CV to 3.65, and CC to as high as you can. The current will drop as they get to 3.65V( assuming your PS supports CC and CV).
It takes quite a while.
A 304Ah cell can be charged with a good 300A when it is empty.
The power supply delivers a maximum of 20A. So 15 times less than the cell can tolerate.
This eliminates the need for constant current charging with 300A.
It is important to maintain the maximum Voltage ! 3.65V top, better 3.60
@@jensschroder8214 the discharge yes is 1C 304A but the charging is 0.5C or 152A per cell. Since she have 16 on parallel teorically will be 2432A only LOLLL.
You don't want to maintain lithium cells at that high voltage, that should only be considered a "withstand" voltage. Since she's using a 20 amp power supply to charge a 4,880 amp hour battery, that would be maintaining that voltage for way too long. This is better done at 3.45 to 3.5 volts, depending on ambient temperature. The cells will charge to full capacity, but require a longer absorption time. You have plenty of absorption time, when it takes 11 days to charge the battery, if it were completely discharged.
As others have said, I strongly suggest you do a lot more reading, especially with the Victron gear, and a lot more learning, Andy's Off Grid Garage is a great place to start the learning. Start with his first videos and go from there. You really should do this before progressing any further, as you clearly have not done any research. Building batteries and a Victron system is a mammoth task, and there is a lot, and I mean a lot to learn. Victron system are incredibly flexible, which means a multitude of settings, and if you just connect it up your without knowing what you are doing, like in this video then you'll be in for a very nasty shock, possibly literally! I have a Victron 48/10000 and 29kWh of batteries, I did the complete DC install, and all programming, so I do know what I'm talking about. I never top balanced the cells either, I checked voltages and internal resistance, hooked it all up and they are perfectly balanced. Grade A cells purchased from Fogstar Batteries in the UK. Please heed this advice. If I was doing it again, I'd probably buy prebuilt batteries, Fogstar have a great range, as do many other suppliers.
Putting 16 cells in parallel i would connect the + pole to the first battery and the - to the last one. Just to take care of minimal resistantce of the bus bars.
Thank you for giving us all this free content, just remember all the "experts" in the comments help you channel get views 😉 I love the fact your making your own batteries, your a star, keep up the good work, can't wait to see the finished outcome ❤
Thanks for that!
Check each individual cell first, while confirming that the poles are correctly labeled or colored. Don't place the bench between you and the exit. In case you need to exit suddenly and flames have blocked your exit...
Lots of smart people here that can't read the title of video. 🤣
With a new pack, connect it as you want to use it with the BMS in place. The BMS job is also to balance the pack. The first charge you do at a low current to give the BMS time to do the balancing and it will not shut down. Different ways to do it.
Older tech. BMS units have little ability to balance out battery banks with large cells.. In the last couple of years one and two amp active balancing that can be set to all the time or just during the upper part of the charging cycle.. These active balancers have eliminated the 3.6/3.65v top balance requirement so you can assemble everything and walk you charge current and voltage up making the whole process much faster and eliminating the need for a low voltage high amperage bench power supply.. If you have factory new virgin cells I recommend a light amount of compression of the cells during their first 10 or so conditioning cycles to allow any trapped gas bubbles to migrate out of the laminations.. After that no compression is required as long as you don't charge the battery cells to over 3.5v or charge/discharge over .3c...
This method of top balance is no longer a thing if you buy a BMS that has active balance at 2 amps or you get one of the external active balancers made for commissioning battery packs of this size since they can handle up to 15 amps.. These things are a must for someone who plans to build many multi cell batteries because they can do the work in a few hours compared to a 2 amp built in balancer that will take up to 2 days.. Cost is far less then a bench power supply at $35 to $80 US like this unit , NEEY 15A Smart Active Balancer.. In this manner you can use your inverters charger that might supply 50 to 100+ amps for large 280a to 300a+..
You're absolutely correct the second battery I built I didn't need to top balance the cells at all much easier
I have heard you still wanna give them an initial balance and monthly or quarterly rebalance. Keeps the BMS from being overstresses
@@freddurstedgebono6029 A newly compiled set of cells with a newer 2 amp or larger "smart" balancer in the BMS no longer require any of these high voltage balance/rebalance stressing.. You just slowly walk the charge voltage up to 3.6v per cell allowing the auto balance to do the adjusting for a bit and you can drop the voltage back down to 3.45v to 3.5v per cell and forget it unless a cell decides to become unstable and in that event you could try to boost that one cell to see if it becomes stable and if not it may be damaged internally and need replacing.. Yes you can drop in a new cell of younger age without a problem except it will only function at the level of the older cells..
The simplest best way to top balance that ive found is just get a cheap active balancer. Hook it up... fully charge let set overnight then top off the charge. Then disconnect active balancer and they are good to go
Active balancers are great if you have a mismatch of cells. For new batteries, like here, it is unnecessary. Save your money.
@@StuartJ I buy grade a eve 280k cells new but when I top balance I just hook up active balancer to top balance quickly. Id never leave an active balancer connected while actually using the battery
@@matthewknight5641 i guess if your building a lot of batteries it makes sense. What active balancer do you use?
@@StuartJ it just like the heltech but a different brand. I'm an over the road truck driver and only home 2 day a month so I didn't have time to top balance normally so it was well worth the 30 dollar balancer to make balancing happen in a few hours rather than days or weeks
The problem with this plan is that you end up with a pack that’s balanced as the active balancer sees is correct - they have a limited resolution. Fine if you’re going to use this balancer in your final pack, but not the best balance if you’re not. Just parallel them sit and save your money, you’ll get a better balance.
Top balancing sucks because it takes forever and you have to just be patient because it’s worth it
Just something that I do maybe important or not, top balance with your leads, one on a positive of the first battery and the other on the negative of the last battery.
doing great! next time maybey compress the prismatic cells to prevent bloating
You mentioned you'd provide a link to the batteries, not finding one. If you'd be so kind. Love the video and the accent, great job.
I got the battery cells from Shenzhen Qishou Technology Limited
qsolifepo4cell.en.alibaba.com/
I've had 2 lots from them so far and they've been absolutely brilliant.
The battery case I got from eelbattery.myshopify.com/
FYI - remove that ring from your finger. The one time I forgot, I paid the the price..... Big burn all the way around my finger. Also, 3.2v is not fully charged. It's almost dead. 3.65 is fully charged for a LIFEPO4 (all LIFEPO4 cells).
Placing all those cells in parallel adds up to 4,880 amp hours. I hope you weren't in a hurry. That would take 11 days to charge, at 20 amps. The only thing I would have done differently, is connect the negative cable to one end of the row, and connect the positive to the other end. No mistake was made, the best way to equalize cells is a long slow charge like this. The only reason for top-balancing cells is to compensate for differences in self-discharge rates, and, time on the shelf. You actually want them connected in parallel for several days, if not a week or more. I usually top-balance with a lower finishing voltage, around 3.5 volts per cell if cold, 3.45 if warm. Lower voltage means longer absorption time, which means lower tail current for a longer period of time. That minimizes stress on the cells, and ensures full capacity.
I think to preserve the longevity of the batteries charge in parallel at 3.45 * 16 =55.2. In parallel connections charge to 3.5 max to x tend the live batteries.
You don’t realise how easy it is to loose sight in an eye, just one piece of flying hot metal from a short and you’re screwed.
Would you happen to have the link to buying these cells? Wanna make sure I don’t order from a supplier that’ll send me something that’ll catch fire immediately lol
People how have no idea about batteries make tutorials.😢
Handling with possible 1500-3000 Amps i would strongly recommend using insulated tools. Accidentally shorting would lead to al powerfull welding station…
3.65 volts
And one cable at each end
I have a small DIY solar system. I can charge my batteries in a couple of hours with a 5 amp charger.
Should you need to unpack anything like that again, you should find ...
laying the box on its side and cutting the the bottom open ...
then returning the box up the right way with the flaps opened outwards or removed,
far easier to unpack because you can then slide the box up and off,
thusly allowing you to remove the polystyrene packaging from the top and sides,
leaving you only needing to lift the contents a short distance to set it down free from the polystyrene that it was sitting on.
charge with 3.65 volt
carga é de 3.65 v
Pls protect you hand and finger with a glove
3.65
Great video, don’t take the knocks in the comments to heart, we all have to start somewhere and i enjoyed the video! Everybody’s a professional on here sometimes! ❤️
I appreciate that
You should have charged them while they are compressed, to prevent them from irreversibly expending
They are ment to expand
@@jasperhart1188 *face-palm*
Well what's done is done.
I suggest you read about compressing the cells
304Ah x 16 cells equals 4864Ah. That divided into 20A gives 244 hours.
With 24 hours a day, that's 10.5 days of charging.
Each cell has 3.2V times 304Ah, equals 972Wh. With 16 cells ( multiply ) this results in 15600 Wh or 15.6 kWh.
Charging: 3.2V x 20A results in 64 watts. 15600Wh divided by 64W equals 244 hours.
With 24 hours a day, that's 10.5 days of charging.
244h divided by 24 equals 10.12h Exactly 10 days and 10 hours, calculation uncertainty: 10 1/2 days
If you calculate over Wh you have: 3.2V ÷ 3.2V = 1 in the calculation.
With Ah you only calculate amps and hours
your plan B wouldn't have worked
To do this you would have had to charge quickly with 300 amps.
This requires arm-thick, no , thigh thick, cables and 4 conductor monitoring.
@@jensschroder8214 The cells are *not* empty.
that other power lead needs to be on the other end of the battery array. Not both connected to the same battery. your voltage is also set wrong. Why don't you know this? never guess something, know, don't guess.
Lady, if those batteries were fully charged and you bridged them all out in parallel, it means you effectively have a 3.2V/4864A explosion in front of you - if you were to then drop your "spanner" (aka torque wrench) on the positive & negative terminals - it would glow red just before it disappears right in front of your own eyes !
I sincerely hope this was an April Fool's joke!?
It is even worse. Without a BMS, each of those cells can discharge somewhere north of 2000A when shorted, so she was sitting on a 32000A arc if she made a mistake.
Blind leading the blind. Here’s what not to do.
Your story makes no sense to me, it sounds that these batteries are a mystery to you that do (or not) except power .
No they are just chemical cells, that have a certain voltage, can except current and have an internal resistance.
The nominal voltage of these cells is 3,2V, fully charged it is 3,65V.
Charging batteries, you do with current, while charging the voltage rises.
When the voltage rises to 3,65V they are full.
When you set the charger to 3.65V the charger will start with a high current, when the voltage of the cells rises it should continue with the same current until they are full (when there is no resistance).
But the current drops slowly until it is nearly zero, this is due to the internal resistance and the resistance of the cables.
It is also important to top balance charge these cells, because the voltage difference between these cells is the highest between 95 and 100% charge, between 10 and 90% the voltage does nearly not change (only 0,2V).
Putting all cells in parallel is good, though it would be better to connect the charge leads in the middle of the row of cells, so the voltage of the cells will be more equal.
Charging and balancing all the batteries is easy. Since the bench power supply is limited by Amps probably at 3.2V 10 amps for example is only 32W output, at that rate will take forever. What you need to do is setup the batteries in series to 24V or 48V if your bench support it and then charging at 24V for example 10A (assuming is your bench PS limit) will be 246W much better than 32W. Once the first cell archive 3.65V then connect everything in parallel and finish balancing at 3.65V to make sure everything is top balanced. I recommend connect an active balancer while charging in series. I have done this many times without BMS in less than 2 days. Also she forgot to compress the batteries because LiFePo4 batteries tend to puff while fully charge or fully discharge. This will prevent damage the cell, also prolong life spawn and performance.
You have BAD habits with tools,I reccommend not messing with these batteries...Or educate yourself...You can't charge that battery the way it is connected from a 48 volt charger, you had better educate yourself, these batteries can be dangerous if you make a mistake..3.65 V is what you want for a capacity test, discharge to 2.5 But, I wouldn't charge past 3.45 in daily use..
Safety glasses please, if this is a tutorial at least make a token effort to do this safely. It’s wreck-less using that uninsulated tool.
Surprising to see the Lady is not well verse with the Lithium technology and she wonder why at 3.2v there is no "charging current"..... so sad to see this happening
I think reading through the comments she’ll will improve, her next video should be ok
Did not see you read the cell voltages, then realized you are a newbie, for your own safety/welfare and other newbies to the matter, kindly educate yourself properly on the subject, cab be LETHAL . . .