TheOffGridGamer
New Member
I have 8 lifepo4 batteries at 12.8v 100amps. How long should they be wired in parallel before charging them with a dedicated charger?
Balancing multiple lifepo4 batteries
- Thread starter TheOffGridGamer
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LakeHouse
Solar Enthusiast
There’s no reason to let them sit wired in parallel, just start charging.
You should check that the voltages are close though before wiring in parallel, otherwise you could have a lot of current flowing between batteries.
TheOffGridGamer
New Member
Here is the catch. I only have a 48v charger. I'm trying to get the batteries as clos as I can before I wire them up in 48v sections. Then I can use the 48v charger to top them off
LakeHouse
Solar Enthusiast
Ah, I see. Wiring them together in parallel won’t help you. Having them at the same voltage tells you nothing about SoC (edit: unless voltage is above 13.6V), and that’s what you need to get equal.
I don’t have a suggestion for how to balance those batteries with only a 48V charger. You might need to pick up a 12V charger.
rodrick
Free energy enthusiast
if your charger has a voltage adjustment you may have to lower the top voltage and slowly over time increase the voltage as the batteries balance out
MisterSandals
Participation Medalist
Connecting them in parallel does very little to no balancing.
Why not wire them up 2P4S or 4S2P and start charging them with your 48V charger? Or do 4S and then 4S.
TheOffGridGamer
New Member
From what the manufacturer pointed out, balancing them out by parallel can be done to equalize them. 
MisterSandals
Participation Medalist
Link?
Put a clamp meter on any of the wires and report back with the amount of balance current you are getting..
TheOffGridGamer
New Member
They have been setting for about 6 hours and the current is reading 0.23 amps
LakeHouse
Solar Enthusiast
No. The manufacturer either doesn’t know how their batteries work, or they’re lying to you.
That will get them to the same voltage, but it won’t balance them.
Let them sit like that overnight. as others have said it will equalize the voltage but thats it. once you wire them in series make sure to check that all cells are similar in voltage and make sure one does not run away and get too high. Thing is it will happen fast once they reach the top end. I would check every hour or so until you get close to the top then every 15 minutes or less if you do not have a BMS
TheOffGridGamer
New Member
Each battery has it's own built in bms board
So if you put them in series what happens when an individual 12v cell reaches its max voltage. Does it have an internal shut off?
So if you put them in series what happens when an individual 12v cell reaches its max voltage. Does it have an internal shut off?
TheOffGridGamer
New Member
The bms board will cutoff at a low and high voltage
TheOffGridGamer
New Member
What I meant to say was to balance them out in parallel, then wire them in series to equal 48v then charge them
DIYrich
Solar Wizard
You need to charge in parallel to 14.4v. Hold that voltage for for a few hours to give the BMS inside each battery time to balance the cells inside the battery.
If they are not the same voltage, then charge individually to some voltage before putting in parallel.
Basically it is the same process as balancing individual 3v cells, but yours are in groups of 4.
Just to clarify, what is the voltage output of the 48v charger?
If they are not the same voltage, then charge individually to some voltage before putting in parallel.
Basically it is the same process as balancing individual 3v cells, but yours are in groups of 4.
Just to clarify, what is the voltage output of the 48v charger?
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If this is true then it should not be a problem. I'm still curious as to how they will perform overtime and if one does go high does the whole pack go down? Are you going to use these as 12v or 48v?
MisterSandals
Participation Medalist
I misunderstood when you said you have 4 batteries at 12.8V. I thought you were saying they were all at 12.8V rather than 12.8V nominal.
Wha are the individual battery voltages at rest and not connected in parallel?
Do you have reason to believe they need help balancing or are you trying to get them to similar voltages before assembling in series?
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