Comment by jacquesm

The pack I built has a balancer, that's what all the red wires on the photograph are for. It uses a charge pump to move some charge around so that the high cells get clipped and the low ones brought up. It keeps the pack within 2 mV. The unit it monitors is the cell group, all 10 of them have a wire to the balancer and a ground for reference. It is very accurate and it wills substantially contribute to the life-span of the pack.