Was it that cell that had the deep dents?
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Yeah that would explain why that happened.
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I got this one on order is it fine?
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It’s probably a different one but welded by the same dummy (me).
Here is the cell that leaked.
Oozed from the 1st weld at the bottom right
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I hope you paid per pixel on that image
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It’s just a white one of this pony
found a hd version for it
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not if it was a lifepo4 cell, although that would probably be ok still.
usually people weld at storage, assemble and wire, manually balance possibly, but also a good idea to verify before you do that to check the BMS is balancing to 4.20.
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They are liion, the pack was at 3.88/3.86 I discharged the ones that were over 3.9 with the hobby charger.
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If it’s a single cell and its lower than the group, charge the cell up then weld it.
If its has enough partner cells @ 3.88v then build that group and charge it as a whole to match the other groups. Follow?
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I think one of the main reasons to weld Pgroups at a lower voltage is if they short at 4.2v it is a bit worse than at 3.7V. Although that is a bit like avoiding being hit by a bus and getting hit by a van instead.
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This was my understanding as well.
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Yeah the rest of the cells in the group are 3.86 I was wondering which is also the voltage of the rest of the p groups that are already welded.
That is clearer, thanks.
Yes, very bad. I can’t see how that is anything other than the electrolyte liquid from inside the cell. It is flammable organic solvents, additives, and dissolved lithium salt. It is toxic and should not be touched.
That cell is useless now.
Because you were lucky. Do not touch the liquid with bare hands and certainly do not weld anywhere near it. It is flammable and toxic. Thoroughly clean anything the liquid might have touched.
Carefully wrap that cell and recycle it.
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Your sad trolling aside the liquid is dangerous, both flammable and poisonous.
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There is a significant difference between cells at 4.2V and down near 3.4V though. This is near the 30% charge point where new cells are taken down to after being manufactured and tested. Going down to this voltage is still way above the 2.5V low voltage rating but leaves a lot less charge in the cell to feed a short-circuit with. This helps prevent a fire if the cells are damaged or otherwise shorted out during shipping or pack assembly,
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Are there any other risks apart from a bigger short potential when welding fully charged cells?
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