Vehicle super, mega fun of it, but battery is fully scrap!

My kids are full of the vehicle excited (Mario we have), just very annoying is that battery (700 mAh) not even hold 15 minutes go out to get (both vehicles) and charging man must each screwdriver, because the battery compartment cover every time must be from and screwed. New more powerful batteries (eg 1200 mAh) costs equal to nearly 17 euros each. So fun is much too short, but for a lot of trouble!