Power rails

[R9000]

I have four 18V drill motors and a brushless RC car motor all powered by three TZ85s, so it's clearly drawing nothing like 400A. I just thought going for the max fuse size I could would be the best, since I can always reuse it anyway. Battery leads are 10AWG, as are the leads going to the removable link and fuse. 12AWG wires branch out from those to the three ESCs, which also use 12AWG wire for output to the motors.

Should I use a much smaller fuse? I have no real way to measure the current drawn - my multimeter only goes up to 10A.
This is the brushless I'm using - it powers my linear actuator: http://www.componentshop.co.uk/lbh36...or-2-pole.html