Hello, my DIY batterypack is completely drained for power due to a power switch malfunction of focbox unity, the 12s4p pack only measures a total of 5.631Volts, and each paralell pack around 0,4Volts.
The 50,4 charger only charges a few millivolts until it stops, do i need to buy a 3,7 volt charger and disconnect all parallells and charge one by one, or do i have any other options. i have a bestech D140 BMS
Itâs a fire hazard now, if you charge it it might go âboomâ or you might successfully bring it back to life just for it to go boom randomly down the road cause of them dendrites.
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what can i do then ? salvage each cell or is it beyond repair since it always will be a firehazard due to dendrites forming from drainage ?
Safely dispose of it by using local facilities. Donât throw it in your dumpster/trash can.
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bummer about the pack. Cells that go below 2.5v are suspect, drain them flat like that and theyâre dead.
I think the only thing to do now is to salvage that BMS, the wiring, connectors, and anything else that might be useful before recycling them cells
RIP
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Check out the cool battery he shows off at first (SPACEXXX) but he also shows off some 13S ebike packs with what look like 40Ts
@Scepterr
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Iâm just (mostly) giving you a hard time.
The 10sec fusing current will be 10-20x the rated amperage of the wire gauge. that should be enough time for the fuse to pop, though itâll get kinda toasty in the meantime and could get hot enough to desolder.
As for recommendations, you donât have to stick the end into the hole of the plug. You can up the gauge (down? conventions are weird) keep the wire parallel (stick a few strands through if you really want for a mechanical wrap) and just solder to the pad/flat.
def donât forget the heatshrink.
@bwahl602 ok 10mm x .2mm strips came in. Did some test weld on a set of LG cells double fold so (so now .4mm at 50 Joule. Guess I need to bump up the joules. I think I gonna remove all strips and start new.
Take a spare cell, drain it to zero volts and test the welder. Make two welds, tear off and inspect. Repeat
Vtc6 are an 18650 battery arenât they?
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Samsung 40T equivalent
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Hardcore battery for a single motor build.
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I got a really good deal on them from a friend so I have them on hand
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@Resonant did you end up replacing this cell or just let it how it is?
The reason I ask is because I had similar happen from time to time with my malectrics.
Might have been because of not clean probes or not right contact or something I donât know off yet. Doesnât matter how much I take care, I have similar happen as min once at each pack I made. It blows through the nickel and a bit into the cell surface.
My question here would be till which point itâs still safe to use the cells?
Is it legit to say it doesnât matter as long as the cell wall isnât punctured or can it already have an negative effect if the cell wall thickness is reduced a bit due to that wrong weld 
I have seen that happen on many other packs as well, but nobody seems to think/worry about that.
So whatâs your guys opinion about it?
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Pretty sure that one, my hand slipped to the part that had nothing under it, and it pulsed as it happened, may have shorted it on accident at the same time. Iâm gonna run with it though, I think itâll be fine. Though Iâm not an expert.
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Poached from facebook
Heâs used tiny little nickel tabs to weld through the copper to the cell. Genius 
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All those super close series connections with no isolation is giving me the spooks but thatâs pretty cool!
I wonder if they is any special method or setup that we canât see. A video of welding a pack like that would be awesome.
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True. Wonder what it would take for them to arc
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Accidentally dropping a plate of copper on there would probably do it! Or even any tiny peice of metal.
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I wonder if there are resources for finding this sort of stuff out ala ampacity charts. Would be cool to see what distances particular voltages and amperages will arc at
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