Adding a Battery Balancer
Some information is here SRX parallel balancing port.
A123 cells with a Astro Flight "Blinky" Li-poly balancer for A123 1-6 cell battery packs.
After six months of usage, I can say that I would never buy a battery without a balancer. I have taken my old battery pack which I thought would need to be replaced, and it is working like new for six months now. I have even rehabilitated by previous battery pack, so that it is now usable.
An added feature of the balance is that by showing which cell is low, I can see if one cell in particular is consistently low. If this occurs, it is a good indication that the wiring or connections to that cell are loose/faulty.
This is the best modification I have done to my 2000XR motorboard.