I wouldn't lock yourself into just thinking about long run times, instead find battery they works with your crawler to make it preform better. You don't want to jam one huge 5000mah battery in there that is going to make it top heavy when you could carry a couple smaller batteries. For example I run 1300mah batteries on my front axle to get my weight down low. I have 4 of these so I can stay out crawling for awhile.
Do you know what cell and how many volts?
My understanding is the higher the mah, c, etc... rating; the longer the runtime. Ive heard a stock rs10 only gets about 20min of play.
What type of battery should i use to get around an hour of play?
"you're RS10 uses 370 motors which are grossly under powered"
Thought the new rs10XT came with 390 motors?
I hope redcat isnt lying to me already, I havent even got my rig yet!
http://www.redcatracing.com/RC-Cars/Rock-Crawlers/Rockslide-RS10-XT-1-10-Scale-Crawler