LiPo heating up on Semi

[JLiang]

So this has been an issue for a bit now and I'm slightly concerned as to the consequences of continuing to use my rifle given the conditions.

I have a G&P 7.4V and 11.1V LiPo. My rifle is wired to GATE NanoASR (Non-AB) MOSFET on a Tienly 45000 Motor.

The issue arises on continued semi fire. After about 10-30 rounds on the 11.1V or around 100 rounds on the 7.4V, the LiPo begins to heat up (and the motor, but to a lesser degree) as well as the MOSFET (but only a bit.)

The LiPo heats up to the point where I can feel it through the grip of my Type 97, where I keep it inside the rifle. It's not uncomfortably hot, but it's pretty dang hot.

Does anyone know why this is? When the LiPo is not hot, the gun operates fine. But, as the LiPo gets hotter, the motor seemingly acts more powerfully and erratically; on the 7.4V, the motor shoots perfectly when the LiPo is cold, but begins to do two cycles or 1.5 cycles per trigger pull when the LiPo is hot.

I am completely out of ideas as to why my LiPo heats up. I haven't observed this phenomenon in Auto, but then again, I rarely use Auto so I don't know.

Any help would be appreciated.

[Spike]

Are you using the 20c 1100mAh ones? If so, they're not putting out enough amps for your set up.

You need a beefier battery.

[JLiang]

Yes, 1Ah 20C.

So it's heating up because it's not powerful enough?

[ThunderCactus]

its heating up because you're drawing more current in the burst rating than it can handle.
I'm also not convinced G&P makes quality lipo batts

[JLiang]

What would be a good LiPo that would provide a sufficient amount of output?

I suppose a better question would be what is the minimum Ah and C ratings that would allow the LiPo to comfortably provide power to my setup?

It makes sense though because my 11.1V is 1.2Ah and 20C, so that would likely be providing not enough power as well.

[Spike]

The short version: As big of a battery as you can possibly cram into your battery compartment. If you decide to go with an 11.1 you might encounter overspin (your gun shooting twice in semi auto), since you're already experiencing it occasionally with a weak battery.

[ThunderCactus]

Or switch to an 11.1v and use an AB-FET

[lurkingknight]

more C and mah... as much as you can put where you are storing your battery... if that still doesn't work, then you will need an external battery bag.

overspin is one of those issues that can be solved a few different ways:

AB fet... some power drain, and it's been debated whether it could wear out motors faster. The motor can also heat up a bit. The fet will reverse the polarity on the motor to stop the motor, no slow down, no nothing, max voltage, instant stop. Kinda not good imo as it's a harsh stop.

Less volts... 11.1 is providing really high rate of fire and good trigger response, but those also come with the potential of overspin, so if you slow the system down to a 7.4 but again with as much mah and C as you can cram to where you are putting it, the overspin should happen less or not at all since there's less momentum in the gears to carry it through another cycle.

smaller motor... you got the tienly so you're going to want to use it. It's a beautiful motor, but using too powerful a motor can result in overspin no matter what.

shorter gears... lower ratio gears are harder to pull, so when the motor is not powered, it will require more energy in the gears to pull the spring, so the gears will slow down more/quicker with the drag, even though it requires less bevel revolutions to cycle the system.

bigger spring... at least a 110 spring and if you're still overspinning on that, then you'll need to... light springs and neo motors generally means you will overspin (among other issues) most neo motors stop doing it with 110 springs, I've had a few builds with the slower tienly motor not overspin with a 100 spring, all my other builds for people were 110 springs and they don't overspin with 13:1 gears. I think I also did one with 19:1s and a 110 and it doesn't overspin.

short stroke... an even bigger spring.. 120 or 130... start taking teeth off the sector gear and piston to shorten the stroke, reducing the volume of air used in the air charge in the cycle. This will drop your fps back down depending on the teeth you grind off but retain the harder to pull spring so the drag after on the system brings the gears to a stop. Short stroke is generally the best way to deal with it and preserve all your other characteristics, you can keep using 11.1 to keep your trigger response and rate of fire without sacrificing your fps, or changing your fet, but requires a bit of technical knowhow on which teeth to remove and how many and from which side of the sector gear.

[ThunderCactus]

The best AB fets don't reverse polarity, they simply short both sides of the motor, using it's own energy generation to stop itself. That's how it works in the ptw.