Can you run 11.1V in a stock AEG?
short answer: technically it works, and you'll break something sooner. for an 11.1v lipo stock aeg with no modifications, i wouldn't do it.
long answer below, because "it breaks" is a lazy warning. you want to know what breaks, why, and when the answer is actually yes.
what 11.1 V precisely does
an 11.1 V LiPo (3 cells) sits at 12.6 V fully charged. a 7.4 V pack (2 cells) sits at 8.4 V full. so that's not 50 percent more, but in practice about 50 percent more voltage on your motor.
what happens:
- the motor spins faster
- the motor pulls more current
- the gearbox cycles faster
- the piston gets pulled back harder and released with more force
- more heat builds up in the motor, the wiring and the gearbox
the upside you notice immediately: tighter trigger response, higher rate of fire, and the replica feels livelier. that's exactly why people do it.
the downside you only notice after a few playing days.
what breaks first
in this order, roughly.
1. the trigger contacts
this is almost always first. in a stock gearbox the full motor current runs through two copper contact points that you push together with the trigger.
more voltage means more current, and more current means a bigger spark at the moment the contacts just about touch or don't. that spark burns material away and black oxidation settles on the surface.
symptoms: you have to pull the trigger further before anything happens, you occasionally get no shot, or it fires on after semi. eventually nothing happens at all.
this is why a MOSFET changes the answer. more on that further down.
2. the piston
the piston teeth mesh with the sector gear. with a faster cycle those teeth take heavier and faster hits.
a stock piston usually has plastic teeth, sometimes with one steel tooth. under 11.1 V those teeth strip: the polycarbonate wears away until the tooth no longer grabs the gear. then you hear clicking and it doesn't cycle properly anymore. i've got a separate piece about this, because the clicking sound is a classic.
3. the gears
especially the sector gear and the pinion on the motor. with wrong motor height combined with 11.1 V the pinion eats into the bevel gear. that happens on 7.4 V too, but on 11.1 V much faster.
motor height, by the way, is the free fix everyone skips. i've written something about that too.
4. pre-engagement and let-off
with a fast cycle everything keeps spinning for a moment after you release the trigger. if the sector gear catches the piston again just then, you get a piston half under tension, and that puts strange forces on the teeth. without active braking that happens regularly.
5. heat and wiring
stock wiring in a lot of AEGs is thin (often 20 or 22 AWG) and the connector is sometimes still Tamiya. that combination adds resistance, and resistance adds heat. you lose part of your extra output to warming up your own wires.
6. cylinder head and spring guide
at high cycle speed the piston slams harder into the cylinder head. an unreinforced cylinder head (with no rubber pad or a thin one) makes that felt.
when the answer is yes
11.1 V is fine if your gearbox is prepared for it. the checklist:
1. a decent MOSFET. this is by far the most important. a MOSFET means the heavy motor current no longer runs through your trigger contacts: they only switch a small signal current anymore. that removes problem number 1 entirely.
a good MOSFET often also offers active braking, where the motor is braked immediately after you release the trigger instead of coasting out. that largely solves problem 4 and makes semi-auto much cleaner.
i've written a more detailed piece in English about MOSFET installation, with when it is and isn't worth it.
2. a decent piston. a piston with more steel teeth, or a fully reinforced piston. do note: a full metal piston head and piston is heavier and creates its own load. for most people a piston with steel teeth on the last positions is enough.
3. correct AOE and shimming. if your piston teeth and the sector gear don't mesh cleanly, that's a slow problem on 7.4 V and a fast problem on 11.1 V. see my English workshop guide on shimming and AOE correction.
4. correct motor height. free, and the most skipped step.
5. heavier wiring and a Deans or XT60 connector. 16 or 18 AWG silicone wire. bin the Tamiya.
6. a motor that suits it. high torque motors are designed to pull a heavy spring. high speed motors spin harder. on 11.1 V with a high speed motor you'll break a lot very fast.
get those six sorted and 11.1 V runs fine. i run 11.1V myself, but not in a stock gearbox.
and the joules?
important misconception: 11.1 V does not make your replica more powerful. the BB's energy is set by your spring, your compression and your barrel, not by your battery voltage. you don't shoot harder, you shoot more often.
your speed changes marginally, usually a few fps from slightly different timing. don't expect an 11.1 V pack to suddenly push you over the limit.
so the limits you play at stay the same. those limits vary by country and by site, and they're not a suggestion. build to whatever your local field enforces and chrono to it.
one thing that is relevant: a higher rate of fire means more BBs per second at close range. some fields have ROF limits in CQB precisely for that reason. ask about it.
what i'd do
new AEG out of the box, no mosfet, you just want to play: 7.4 V. full stop.
new AEG with a factory mosfet (Krytac, Specna Edge, some G&G models): check the manual. a lot of those replicas are explicitly 11.1 V rated. then it's allowed.
you've had the gearbox open and worked through the checklist above: 11.1 V, have fun.
you're not sure: 7.4 V with a pack that has a decent C-rating. a 25C pack on 7.4 V feels better than a weak 11.1 V pack, and that surprises people.
the cheap middle road
if you want faster trigger response without opening the gearbox:
- replace Tamiya with Deans. costs you a soldering iron and ten minutes
- buy a pack with a higher C-rating instead of more volts
- clean your trigger contacts
- set your motor height properly
those four together cost almost nothing and give a noticeable result. do that first, and then see whether you still think you need 11.1 V.
Also on Airsoft-FOB
- also available in dutch: Kan je 11.1V in een standaard AEG gebruiken?