I put new cells in a power tool battery with a BMS. I didn't connect the sensing wires yet because of the weird voltages.
I'm scratching my head. One of these cells measures -15V. The are all just in series and I can't see a short or anything.
From the negative I get these cell measurements 3.3V, -15V, 4V, (the rest are 3-4V)
The cells all measure 3-4v when I remove the nickel strip.
It hasn't caught fire at least.
Simple BMS with cells in series
First cell is 4V
Second is -15V
Third is 3.3V