Aug Upgrades Resulting in Blown Out Battery and Blaster Smoking

I have been working on upgrading my AUG A2 and have put in the following upgrades:

  • 1.18 spring
  • 18:1 Metal Gears (and shimmed)
  • Metal Anti reverse trigger
  • Alloy Barrel
  • Metal Cylinder and Cylinder head w/ Nozzle
  • Metal Tooth piston and metal piston head
  • 480 Torque motor.
  • 11.1v battery (wouldn’t fire on a 7.4)
    After putting in all the upgrades the blaster was firing for about 3 seconds, stopped, started smoking, battery sizzled and blew out as well as the battery connector on the mofset fused to the battery and melted off of the wires. I will need a new mofset or solder/attach a new battery connector. To prevent this happening again in the future, does anyone have any recommendations on what would have caused this and how i can fix it?

First thing is to pull the gearbox apart and make sure it didn’t jam or strip gears internally.


All the gears and internals on the gearbox are ok

If it would not run on 7.4v on a 1.18 spring you either wired the motor backwards or you have shimmed the gears too tight.


Ok, so assuming motor and all the actual wiring is OK it sounds like the mosfet failed? I’ll defer to others who use mosfets to help you further…

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Ill experiment with it a little more later with the shimming and motor and update from there. Is there any way to tell which direction the motor spins? Im assuming clockwise.

Possibly, I will likely get a new one for it. Seems like there was alot of electricity/power running through it before the batter burnt out.

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rebuild it with a secondary mosfet to handle the motor current

test run it with a smaller (stock) spring until you are confident its all ok

install a fuse on the positive conductor as the battery enters the blaster’s wiring harness


I’m pretty sure they turn clockwise, but in any case the terminals are usually colour coded? Start current is quite high on them, my tabletop power supply can’t start them (10A limited).

Definately install a fuse, it’ll at least save the battery next time. And I second the idea to start with stock spring and a 7.4V until everything is working happy.

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Can also happen when the battery connector is reversed resulting in mosfet connections also being reversed though if it was firing it won’t be that.

It can also happen if the MOSFETs are lifted by excess resin during soldering. They cook themselves and everything else.

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Excellent, will try that out first

That diagram is very helpful, thanks

If you leave the tappet plate out and the Piston, u should be able to run the gearbox while it’s still out of the reciever to see how your gears are meshing


You can keep the tappet in too… Check on timing


Is this a LeHui Aug?

I’m running a 1.18 spring fine on 11.1v(stock gearbox) after doing TECH: Using a second MOSFET to protect your fire modes

May be of help. Cheers


That will help a lot thanks!

I also run a mostly stock gearbox with 1.18 and 11.1v and the most I’ve had is a wire on the little clicker on the side coming off. My estimation would also be that the mosfet couldn’t handle the current the upgraded motor needs.

Providing there’s no jam and your shimming was correct.

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I had the exact same wire come off the side counter clicker thingy or whatever it does, the solder was poor. :+1:


Yeah that came off for me too, is it needed on the blaster Or is it a place holder for a trigger? I was also looking at the mofset and I think the component responsible for the motor was kind of melted and bubbled at the top.