The fuse is mostly to stop the electronics pulling too much from the lipo, lipo gets hot and then catches fire. So the rules say you must have a fuse for the maximum the lipo can supply, but in reality you won't get near that with a pair of drill motors. They pull about 30 amps a pair tops. So in that case you could put a 30 amp fuse in and roberts ya mothers brother. If you have weapon motors as well, add the current to 30 ish for the drive and buy for that. It's as complicated as you make it.