I used the battery holder from the perfection light set, because it seemed to be the only good part on the whole thing. And now I'm gonna have to get what ph2t's got on his so I can make mine really bright.
With the weight issue: it is noticeable, but only when turning at high speed with like a 4.2 or something really fast like that. The problem is the battery is located at the top of the body, which is far from ideal. the best place would be to attach it to the chassis, where it is lower and will actually aid in handling.