John, Enersys batteries are great for taking abuse, and high energy, as Garret mentioned. You can also charge them extremely fast. Here are some links (bottom of page) to sources: http://www.stealth316.com/2-dynabatt.htm
A less expensive alternative is to use B&B Batteries. The "EVP" and "EB" series work well for EVs. A few sources: http://www.digikey.com http://www.electricrider.com http://www.zbattery.com NiMH and NiCad cells would work too, depending on the discharge rate. D Cells are the cheapest for energy storage. Known sources for cheap cells: http://www.batteryspace.com http://www.all-battery.com Beware that the D-Cells available from the above sources appear to have high internal resistances, and may not provide much power in a large pack. It may be best to use a hybrid pack in that instance where a small lead-acid pack provides most of the power, using the NiMH/NiCad pack to augment the energy storage, and "feed" the lead-acid pack. SAFT are probably the best quality NiMH/NiCad available. Known source: http://www.batterystore.com Good luck, Andrew
