Hector, there's a few Japanese companies that sell plugs for motors as well. Kinda like "euro plugs". The female end replaces one of the brush hood screws. The male end solders onto the wire.

Anyways, I used to use the Eagle "euro plugs". I had no issues with them. Or never had batteries come undone. But I had to go away from them and back to hardwiring only cause I changed cars (TC4). Now that I no longer have the car, I have been considering goin back to euro plugs again. It's alot less hassle for me. Especially if I go to a club race that ends up being in a parking lot that does have power.