I decided to re do my A123 M1 4S SPT packs to add taps.
The 4S taps are from www.allerc.com
and I purchased a Hyperion LBA10 at the same time.
Adding the taps was quite easy. I soldered lead 1 to the main pos terminal, lead 3 to the end cap battery bar and lead 5 to the main neg terminal. For lead 2, I soldered a battery bar end to the wire to increase the surface area and taped and shrink warped the lead to the body of cell 2. Added the bar end to lead 4 and taped and shrink wraped it to the body of battery 4.
Advantage: nothing is soldered directly to the cells.
I usually charge with my Astro 109 and decrease the current after the pack reaches 3.6v per cell. This manual CV phase usually takes a few minutes, but hopefully astrobob will come out with a chip to make this automatic.
When I balance with the LBA10 usually 2 cells are in low discharge and 1 cell in high. Within a few minutes the balancer shows a full balance (all lights off).
Is balancing necessary? Not sure but it can't hurt.