http://www.hobbypartz.com/83p-800mah-2s1p-74-15c.html

Started using these last summer. Ordered 5 of them just in case. They have slightly over an hour run time when you count warm up time before the race.

Before these batteries I kept trying to use LiPo's with 1500mah and 2000mah capacity, but they were dropping like flies. The off road use kept causing them to short out or just swell. So when I switched to the little batteries in the link above I could put more foam padding around them for more protection. And surprise...they come out looking new, work perfect, and no more battery failures.