Advice on balancing 16 x 12v LiFePo4 batteries
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timselectric
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If you haven't already purchased the 12v batteries, don't. You should use the proper voltage batteries for your system.
But if you are already stuck with them, then you will need 4 balancers. (1 for each string)
People have recommended a couple of good ones. But I don't remember which they were.
I'm sure that someone will say, shortly.
But if you are already stuck with them, then you will need 4 balancers. (1 for each string)
People have recommended a couple of good ones. But I don't remember which they were.
I'm sure that someone will say, shortly.
Something like this:
https://www.aliexpress.us/item/3256805860209321.html
Need 4. No endorsement, shop around.
https://www.aliexpress.us/item/3256805860209321.html
Need 4. No endorsement, shop around.
cs1234
Solar Wizard
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Wow, that's a really good price.
timselectric
If I can do it, you can do it.
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That is a really good price for 10a balancing current.
(also, not an endorsement)
(also, not an endorsement)
Brucey
Solar Wizard
The litime balancer is a 10A unit, works well for me with four Redodo 12V 100Ah minis. Use one for each of your battery strings.
robbob2112
Doing more research, mosty harmless
I personally like the LiTime branded version - similar in specs - higher price point - has a few protections built in.
www.litime.com
LiTime 48V Battery Balancer for 24V/36V/48V Battery Bank
The LiTime 48V battery balancer is suitable for multiple battery types on the market, including LiFePO4 and lead acid. Compatible with 24V, 36V, and 48V battery bank.
www.litime.com
Brucey
Solar Wizard
Each string should equalize assuming they are all connected to a common bus and the battery cable lengths are the same.
robbob2112
Doing more research, mosty harmless
Each string should have a class T fuse at the positive end of them. This keeps the other strings from dumping into a shorted or lower voltage string if there is a problem.
Connected to the same bus bar pairs they should come close to balancing on their own. There is a link to a thread in my signature about parallel batteries and how to ensure they are balanced.
Thanks. I'm actually doubling the capacity of an existing system. The existing system has 8 batteries, 2 strings of 48v. It ended up not being enough to last the night, so that's why I want to expand it.
Thanks. There's some good info in your links.
Could you please help me size the class T fuses? I don't trust my math on it.
I'll have 4 strings of 48v. The inverter supports up to 5kw, but in reality the max draw is about 1.2kw.
robbob2112
Doing more research, mosty harmless
Size them to 20% over your BMS output current.
If you need to round, then round up. So for a 100amp BMS a 120amp fuse, but gets rounded to 125amps. For a 200amp BMS 240a is what it comes up as but gets rounded up to 250a. When we recommend the class T fuses we are talking about the JLLN spec fuses. The Blue Sea systems ignition protected holder is a nice to contain the fuse, but you can use and real brand of mount.
Blue Sea systems uses Eaton and littelfuse to make their products to their specs. Most of the class T I ordered from them come in Littelfuse packaging with their name on it and at a premium price.
The wire should be large enough to be 125% of max BMS current.
www.littelfuse.com
If you need to round, then round up. So for a 100amp BMS a 120amp fuse, but gets rounded to 125amps. For a 200amp BMS 240a is what it comes up as but gets rounded up to 250a. When we recommend the class T fuses we are talking about the JLLN spec fuses. The Blue Sea systems ignition protected holder is a nice to contain the fuse, but you can use and real brand of mount.
Blue Sea systems uses Eaton and littelfuse to make their products to their specs. Most of the class T I ordered from them come in Littelfuse packaging with their name on it and at a premium price.
The wire should be large enough to be 125% of max BMS current.
JLLN - Littelfuse
Thank you very much for the infoSize them to 20% over your BMS output current.
So for a 100amp BMS a 120amp fuse. If you need to round, then round up. For a 200amp BMS 240a is what it comes up as but gets rounded up to 250a. When we recommend the class T fuses we are talking about the JLLN spec fuses. The Blue Sea systems ignition protected holder is a nice to contain the fuse, but you can use and real brand of mount.
Blue Sea systems uses Eaton and littelfuse to make their products to their specs. Most of the class T I ordered from them come in Littelfuse packaging with their name on it and at a premium price.
The wire should be large enough to be 125% of max BMS current.
JLLN - Littelfuse
timselectric
If I can do it, you can do it.
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I would expand with 48v batteries.
And phase the others out, as they reach the end of their life.
If I'm trying to replace 2 strings of 4 x 12v 300aH batteries, and double that capacity, what configuration would you recommend if I switched to 48v individual batteries? It seems from a quick search that most of them are 100aH?
cs1234
Solar Wizard
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300ah 48v are very large and heavy. Most recommended one on here would be EG4 batteries. The PowerPro.
Thanks. So when they say "all weather", it really is okay to put them out in the summer heat?
cs1234
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Best that it be on a shaded part of the house. Direct sunlight assault not recommended.
Brucey
Solar Wizard
The ecoflow 12V 280Ah are usually around $500 on Amazon. Four of those is $2k shipped, versus the eg4 at $3400+shipping.
Depends on what your budget is.
Personally I like to keep the batteries inside away from extremes of temperature (too hot - affects cell lifetime, below freezing shouldn't charge).
Is the existing system built of lithium batteries and do they already have balancers? If answer is "yes, no" it might be failing to meet your needs, not because it's too small for your use case, but because it's gotten out-of-balance and its capacity is reduced.
I'd take a look at your instrumentation and find out what its actual capacity is currently, and if it's far below rating I'd start by forcing them back into balance, buying the balancers, and hooking them up, then running for a while.
Buying balancers is WAY cheaper than buying balancers plus batteries, and if you buy balancers that are also suitable for the contemplated upgrade you're only out time and fussing about if it turns out you still need to replace the current batteries.
timselectric
If I can do it, you can do it.
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I build my own diy batteries from 280ah cells.
For a large capacity bank, you can't beat the price.
But if you need to pass an inspection, you'll have to buy pre maid certified batteries.
The 100ah server rack batteries are about 50 lbs each. I would not want to move anything heavier. And the prices are pretty reasonable.
Brucey
Solar Wizard
The rack mounts are closer to a 100 lbs. The 50Ah between 40-50lbs.
timselectric
If I can do it, you can do it.
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Maybe this is why mine seems so heavy.
I thought that I was just getting old.
I also just got the Li-time balancer today for a 48V bank of 12V LFP. (A single large battery would not fit in the space so there was little choice)
I have not tried it out yet but I was surprised at the weight. There is something in the case for sure. Passive draw is 5mA, so lower than the one linked for Alibaba.
I had a $30 off coupon from points, so it was only $20 shipped.
I have not tried it out yet but I was surprised at the weight. There is something in the case for sure. Passive draw is 5mA, so lower than the one linked for Alibaba.
I had a $30 off coupon from points, so it was only $20 shipped.
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