So I'm working on a friend's M4 doing a rebuild because the stock gearbox was @#$%. It's rebuilt as such: Matrix Zombie Killer 8mm Gearbox Base Modify 8mm Steel Bearings Stock 18:1 Gears ZCI Torque Motor w/pinion from the original motor to match the bevel NukeFet w/24a Resetting Fuse - Deans XT's SHS M110 w/Bearing Spring Guide Stock Piston(Aoe/Glued, Lightened) w/SHS orange piston head - no bearing. Batteries are: - Turnigy Nanotech 2000Mah 15c 11.1v - G&P 1600Mah Small Type NiMh So my question is this - with a ZCI Torque motor with the 22TPA armature - I'm actually running into an odd issue(I think). The gears are shimmed well, I get 10+ rotations with a light flick of the sector gear with the shell screwed shut and it was shimmed bevel to pinion. Each gear has about .05mm of play so I know they're not too tightly shimmed. With a fully charged 11.1v, I get overspin issues causing it to cycle twice per trigger pull, and on the 9.6v the trigger response is all but instant, so the motor is clearly not struggling. Yet the batteries I'm running it on are dropping voltage quickly, including a brand new Turnigy NanoTech 11.1v 2000Mah 15c cell. It's got a 30A discharge, and that should be fine for a setup like this, but after a handful of bursts and a bit of semi auto, the fuse gets quite warm, even the mosfet starts to barely warm up, and the LiPo dips low enough to cause my battery sensor plugged into the JST port to go red and beep at me. I've heard about motors running around the 50% max speed mark achieve maximum efficiency(Mostly the discussions about Lonex motors). So I was wondering, could it be that my motor is running a setup that is too light for it, and is somehow running inefficiently and drawing too much power because of that? Or am I missing the point entirely, and should be using a slower battery so that it operates closer to the 50% of max speed mark?