So the battery i have is an 11.1V 3S LiPo.
The battery compartment seems to be confined also. Its not a hard case and was assured that it wont expand when it gets hot (it definitely has) so once run its almost impossible to get it from the compartment. Its pretty well ventilated as well.
It has a spacer in there which ive now removed but the battery will move around (probably has 5-6mm play either side and about 10mm above.
So im not sure which way i'll go as i dont want to spend a fortune on it as im sort of deciding if i want to buy another car also (perhaps the Losi super baja rey, or a rovan 5iveT)
But i still want to enjoy this one now, so i may bite the bullet and buy a cpl of the recommended Spektrum LiPos. (car is full spektrum kit out) and if i buy 2 3s batteries they go in the super rey too (it takes 8s LiPo)