Help needed, Li-Ion pack wiring

[Skysurfer]

Hi, guys.
I've obtained a second hand Li-Ion pack off a wheelchair. The cells seem to be OK, 64 of them!
I don't think they're A123's, as there's no indication of that on them. I bought an excellent balance charger from Overlander, Lipo Battery Balance Charger Overlander RC-8S Pro | Overlander Batteries
and would recommend this for up to 8s packs.
My question is, how is this pack wired? It's nominal 24v (just what I need). I thought it would be 8s, but my charger sees 7s.
I've bought an 8s balance lead, but am scratching my head as to where I should tap the cells.
The pack case is well made, and splits easily, but the cells will require prising apart with a crowbar! Chinese glue is damned good stuff!
Thanks for any consideration, folks.

 

[Deleted member 4366]

Hi, guys.
I've obtained a second hand Li-Ion pack off a wheelchair. The cells seem to be OK, 64 of them!
I don't think they're A123's, as there's no indication of that on them. I bought an excellent balance charger from Overlander, Lipo Battery Balance Charger Overlander RC-8S Pro | Overlander Batteries

and would recommend this for up to 8s packs.
My question is, how is this pack wired? It's nominal 24v (just what I need). I thought it would be 8s, but my charger sees 7s.
I've bought an 8s balance lead, but am scratching my head as to where I should tap the cells.
The pack case is well made, and splits easily, but the cells will require prising apart with a crowbar! Chinese glue is damned good stuff!
Thanks for any consideration, folks.

They'll be normal 18650 cells, so 64 of them has to be 8S8P configuration as it's not divisible by 7. You have to dismantle to expose the cell connections at least to where the balance wires are attached, then you should be able to figure out the 8 packs of 8 and check each cell-group for their voltages with a voltmeter.. Anything less than 3.0v is bad news. If your charger is only seeing 7S, it could be because a balance wire is off (common problem) or the BMS has drained cell-group one. Some chargers won't charge if they see a cell less than 3.0v, so you need to individually charge it with a 5v charger first.