Please under stand WAY to much emphasis on BATTERIES.
This is how in order of importance
Driver. Tires , Car set up , Gearing , Motor, Charger ,Then BATTERIES
Driver = the best batteries & and car tires and motor will not will not overcome DRIVER
Tires= the best DRIVER, Car, motor, charger, batteries, will not overcome the wrong Tires.
Car set up= The best Batteries will not work with a poor handing car.
Gearing = the best batteries with the wrong role out will not work well.
Motor= the best packs with a slow inefficient motor will not work well.
Charger= the best killer pack in the world will not work if the charger is not compleatly charging the pack all the way or is over charging your pack. I have seen AC current leaking out of some chargers and killing packs.
Remember you need a clean DC charger , no AC leaking .