What is the dimensions of the tab?
Any specs sheet on the cell?
Push button overriding charge voltage resistor or diode inline. Cool, right?
How do you want to use brushed type motor controller on 3 phase BLDC "motor"?
Adding cable length can be the wrong way to go as you ad inductance and stress on the electronics. Shortening weld pulses by lowering J value may have better results on reliability.