Made an enclosure with some paddings and made sure that wires are loose and that nickel stripes won’t cut the wires.
Then i wrapped it on duct tape so it’s sealed.
What do you think could have caused it? All the cells were oriented the right way, and connections were triple checked.
This was the very first time those cells were under a charge. series charging without balancing on 2A current. So it’s 0,2C rate.
Dude, cover the cells with some tape from next time, cells might have touched and caused this, you are lucky that there is no major damage beside of burning up your cells.
After Soldiering all the wires make sure there is no contact point for anything to touch the +&- parts of the Battery
Hmm. I’m going to shrink-wrap the next cells from now on. But i don’t think that was the case here of those rubbing to each other. But good point.
And i’m going to use double cardboards on positive terminals also.
Discolored? Hmm… Googling a little… yea they are discolored, meaning there is big currents going in spot-welder.
I have adjusted the settings, so that it welds that nickel stripe i have, not any thicker. Settings are 50ms pulse, 500ms wait, 400ms pulse. The current is that i remember, around 1000A-1300A
Wait, did you not insulate them in the middle? I’m surprised it lasted till the first charge, the one time i made that mistake my whole pack instantly started to short and a nickel strip fused to save the day, and it happened because i had opened and uninsulated the whole thing for maintenance and my hand slipped while doing it!
I clicked the photos, the discoloration is the sort that happens from lotta lotta heat. Like when cutting tools are burnt, and lose their temper and edgeholding ability. Very consistent amount of it on each weld.
I’m voting for damaged cells.
Only 2A charge current…
@Quezacotl if you have a spare cell, maybe weld nickel to the terminals (with same heat discoloration) and try to charge that single cell, see if flames shoot out? Make sure camera is running this time.
1 cell is probably not going to be conclusive, but it should give you more information on whether you need to rethink your welder.