OK guys, thank you very much! !!. I have a xl2 esc I am putting in a rampage mt and the guy at castle says I need at least a 70c 7000mah and only recommends thunder power which to be honest I don't believe it needs all that and thunder power lipos like that cost 300 or over per pack so I will get 2 8s batteries and run them in parallel , I will go with a minimum of 30c and 5000mah a pack. Unless I get lucky and find some good 4s packs at a killer price