I would charge it through the balance leads over dismantling and I would not apply 1A per a cell at all go lower if it’s a 4P pack if you screwed up 3 of the cells 1 cell might be taking all the amps
I would be exspecting to take all day to slowly charge it under constant supervision and repeatedly checking the temp
I would not fully charge the pack I would get the p groups up to 3v and manually balance them
What you need to do is idetayfi if any of the p groups has revived any damage. Easy way to do this is to see if any of the charge or discharge difrent from each other. You can’t do that untill you have very carefully brought them back up to a safe voltage
A BMS and a brick charger is fine when your battery’s are within the safe voltage of the manufacture sets out.
You need respect that all the battery’s in this pack are classed as abused and manufacture state thay should be disposed of.
Any thing after this is at your own risk me and the forum take no responsibility for you actions or damage this may cause
Attempting to savage battery’s I class then all as unuserble and any thing that survives is a bonus be prepared that the pack may end up on fire. If you want garentees on saving don’t discharge below manufacture minimum voltage.
You need tools to monitor and be able to vary the voltage and amps a lab supply has all ready been Suggested personally I use a ISDT smart battry charger in and use a ledacid type battry mode (any good charger or BMS should stop you charging if li-ion the pack is below a safe voltage)
You need to bring them back to a safe voltage but exspect the worst to happen I start by charging a p group at 0.1a in CC mode I want to see the voltage slowly rise with out the pack temp rising to much rember the cells are in a very fragile state so don’t push them or you will cause more damage. If you can’t feel the temp rise after 10min I would increase the amps by .1 each time. Think worst case 1 cell is good in the p group so all the charge could be going in to that 1 cell so check the temp by toutching every cell repeatedly for the same reason I wouldn’t go much higher than 0.5amp untill I’m past 2.6v. Then I would push them a little to see if I can feel them to start to heat up a few degrees up to 3V if you pushing 1amp in a 4P and it’s rising you probably got issues in that P group.
Repeat this untill all Groups are at 3v
I would then let the pack rest untill the next day checking voltage ones in a wile. If 1 p group is dropping them it’s a sign that groups having issues.
Hopefully every thing is ok and will probably dropped voltage a little bit to 2.8v a p group now I would charge the hole pack on a genital charge say any thing up to 1A a cell up to 3.8-4v a p group you want to watch the voltages of every p group looking for anger group charging faster or slower than the Others or heating up. if any do it’s a sign of the group has issues.
Then I would do a 5-10 minor discharge test checking p group voltages often if you ridding the board to do this be general don’t Bome it. You looking for any p group dropping voltages quicker than otheres or heating up.
If all is still good I would attach the BMS charge the pack till the BMS was done check the voltages of each p group confirming the BMS did its job. use the board generally checking p group voltages every few days or Temps and voltages after short rids. BMS can hide or be the issue by dong the steps with out the BMS it should have flagged up any cells that are having issues so you are aware with out the BMS hiding them
Cheep BMS often have a leakage and discharge the battry slowly in storage this is most likely your issue. Either use better quality components or matain a storage charge on you packs periodically frequency determined by how fast it drains
If you wanted my take. It is not worth burning your house down over. You clearly don’t have a proper grasp on the skills it will take to fix this battery or the tools to attempt to do so even if you did its still a terrible idea. These cells need to be married together.
You don’t want to mix new/old cells in general unless you know what you’re doing. It really really sucks but just save a little money and get a really quality replacement and read up on how to store it! li-Ion batteries are not to be fucked with. Do not think someone on this forum knows exactly how to help you and go prying apart electric components that could cause serious harm if mishandled. Even if they are an expert. You are not. It isn’t worth it. Just my opinion.
