This equipment doesn't match a more specific subforum, so I'm posting here.
I have a 36V 9Ah battery pack for an electric bike that is not charging well and has a lower voltage than nominal.
I've disassembled it and it consists of a matrix of 20x CGR18650CG Lithium Ion cells. It's arranged in a 10x4 grid, meaning: 10 packs in series of 4 cells in parallel (10 x 3.6V = 36V; 4 x 2250mAh = 9Ah).
I've measured each pack of 4 cells and the first ones (from first (+) to sixth) they all read about 4V (correct), while from seventh to tenth (-) they read between 1.5 and 1.9V. I've split the individual cells of this 4 suspicious groups, hoping to find one of them specially dead... but not. All cells in a group read the same low voltage, not higher, not lower than the whole parallel group.
The charger has a test point to each union between the 10 packs.
What can be wrong? I've seen several vids on YT that show how to revive LiIon cells, but that trick doesn't seem to apply to these.
I have a 36V 9Ah battery pack for an electric bike that is not charging well and has a lower voltage than nominal.
I've disassembled it and it consists of a matrix of 20x CGR18650CG Lithium Ion cells. It's arranged in a 10x4 grid, meaning: 10 packs in series of 4 cells in parallel (10 x 3.6V = 36V; 4 x 2250mAh = 9Ah).
I've measured each pack of 4 cells and the first ones (from first (+) to sixth) they all read about 4V (correct), while from seventh to tenth (-) they read between 1.5 and 1.9V. I've split the individual cells of this 4 suspicious groups, hoping to find one of them specially dead... but not. All cells in a group read the same low voltage, not higher, not lower than the whole parallel group.
The charger has a test point to each union between the 10 packs.
What can be wrong? I've seen several vids on YT that show how to revive LiIon cells, but that trick doesn't seem to apply to these.
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