Motor overheating

[CJay]

Hey guys here's the setup:

Raptor v2 active braking enabled.
Guarder infinite torque motor.
20c continuous 3200mAh lipo.
M90 spring/m130 spring

Basically I'm cooking the motor enough that the magnets demagnetise and lose torque. happens on both the high energy and low energy springs.

Anyone got any ideas on how I can stop the motor overheating other than turnin off active braking. If I turn it off I get double tap in semi :S

[Scopedog]

Try a lipo with a lower discharge and/or mAh rating.

According to how the number of amps delivered are calculated with your current battery, you're discharging at a whopping 64amps.

20C x 3200mAh / 1000 = 64A

The average discharge for lipo's in airsoft are in the 30A to 40A range, With the upper end being just over 50A.

I'm not an expert on the subject by any means, but the bit of research I just did would seem to indicate that you may simply be drawing much more current than necessary.

[HKGhost]

Only way is to turn off the AB. AB are motor killers.

[L473ncy]

Are you using AB and going full auto? If so there's your problem. AB is pretty much for single shot/DMR only because if you go full auto too much the AB will instantly stop the motor and does that by reversing polarity to "halt" any over spinning.

[CJay]

Not using full auto lol. I wouldn't care bout braking in full cos really it doesn't make any real difference. I'm using the chip on a gun rate at 350 and also on another shooting at 510. Same overspin in both with ab disabled. Might just switch to usin a large type nimh 9.6 4800. Probs be easier on the temp side of things. Anyway the ab I doubt alone is responsible because the active brake won't affect the magnets. Wears ur brushes faster but that's it really. I'm actually fryin either te transfer node or the magnets with overheating. Brushes are easy to swap or but brushes are fine on full rebuild of the motor. No discolouring o the parts that count but the resistance to turning is lower so defo the magnets losing polarity.

[venture]

Originally Posted by CJay

Not using full auto lol. I wouldn't care bout braking in full cos really it doesn't make any real difference. I'm using the chip on a gun rate at 350 and also on another shooting at 510. Same overspin in both with ab disabled. Might just switch to usin a large type nimh 9.6 4800. Probs be easier on the temp side of things. Anyway the ab I doubt alone is responsible because the active brake won't affect the magnets. Wears ur brushes faster but that's it really. I'm actually fryin either te transfer node or the magnets with overheating. Brushes are easy to swap or but brushes are fine on full rebuild of the motor. No discolouring o the parts that count but the resistance to turning is lower so defo the magnets losing polarity.

Sounds like you know your stuff quite well (probably better than me), but if you are causing that much heat you will damage the commutator and the windings will eventually burn off as well. It short, your motor will soon be toast!

You are basically running your motor at more than its rated horse power (if we were talking about larger motors). Heat generated is proportional to the square of the additional power you are generating. Thus things get out of hand rather quickly when dealing with massive overloads of electric motors.

Severe overheat can often be connect directly to undervoltage/voltage sags. As voltage lowers, the motor draws more amps (current) this produces more heat. I am puzzled as to how these mosfets cause these heat problems and am wondering if they experience / cause voltage sags that cause amperage draw to spike. Considering the battery you are using it is more likely that you are overdriving it a bit too much. . . But then, why can you use everything but the mosfet and not overheat motors?? . . . experts, please help . I am just a DIY'er

[Azathoth]

Silly question CJay,

is their an abundance of black fine powder or grit in your pistol grip? How old is your motor and has overheating always been a issue?

I would probably start by looking at the brushes on your motor and the springs that applying pressure on them. Their maybe too much force on the brushes

[MaciekA]

I have the Guarder ITU motor running with a M120 spring, high speed gears, and the Raptor FET. I'm also running it on high discharge LiPos.

I am unable to reproduce your experience with overheating, in fact, this setup runs fairly cool.

Shot in the dark, but have you tried running this setup on a 30C or 40C battery?

I mention this because I have actually experienced heating up of motors (M170 Devil Jet for example) when there was a *lack* of juice, not an abundance of juice. Sounds crazy, I know.

Also, have you tried another motor of similar torque/magnet spec, for example the JG Blue?

[XZIVR]

Originally Posted by L473ncy

Are you using AB and going full auto? If so there's your problem. AB is pretty much for single shot/DMR only because if you go full auto too much the AB will instantly stop the motor and does that by reversing polarity to "halt" any over spinning.

I dont think the raptor can reverse the polarity. The positive wire on the motor goes directly to the battery, not through the raptor. For most small DC motor applications such as airsoft, RC cars and RC planes, the braking works by shorting the motor poles to cause a current loop and stop the motor that way.


If you'd like to try it out for yourself, take a motor (not in a gun), connect it directly to the battery, and let it spin up. Then quickly take the leads off the battery and touch them together. The motor stops, instantly.

[Gunny_McSmith]

Could the "adaptive 10rps" mode also ruin my motor?

(I'm using it because I run a 11.1v in my Scar-H and I dont like shredding pistons....)

[CJay]

Brand new motors and overheat has never been an issue before the MOSFET. But then I never extensively games the gun without the MOSFET.

I've actually managed to fry a tm eg30000 and 2 guarder infinite torques on 2 different guns using 2 different raptor units and was using a 35c 3300mAh 11.1v battery to start with.

Suffice to say tr motor is most definitely not starved for juice. I'm leaning more towards the likelihood of it being too powerful a battery at the moment.

On another note te first guarder and the tm I fried both had large deposits of carbon type powder on em. That's something I just put down to the active break wearing out the brushes quicker.

[CJay]

Here's a thought. Will a lower capacity lipo be easier on the motor? I'm unfamiliar with how lipos deliver charge based on capacity. Is it similar to nimh or is lipo a totally different setup?

[XZIVR]

The lipo can't "force" more current into your motor than it will draw. And the active braking doesn't have anything to do with lipo capacity or discharge rate, since at the point where it begins braking, the power from the battery has already been cut off. Lipo only affects things when the motor is turning.


I have a wattmeter that measures the current draw as well as the voltage drop of the battery under load. Use it for my RC planes to make sure the propellor is sized correctly to the motor. I hooked it up to one of my guns and it drew about 25 amps. Now, if the battery is only able to supply say 10 amps, the motor will take it all, and draw 10 amps. Which is bad for the battery, for the motor to try to draw more than the battery can supply. But if the lipo is able to supply MORE than 25 amps, be it 26 amps or 26 MILLION amps, the motor will still draw 25, because that's as much as is physically possible.


Incidentally, the AWS claim that the raptor can handle 100 amps is BS IMO. We had this discussion on another board and an engineer I know personally posted this:

Edit - I went downstairs to our electrical dept and had my electrical engineer calculate the required PCB trace thickness to transfer 200 amps continously with a 70°C temp rise (95°C / 203°F total). Assuming the trace is 2mm thick, it would need to be 245mm wide. If we let the copper get hot, say 200°C / 392°F, then we can get away with only 130mm wide traces...

I know he's talking about 200 amps not 100, but still, look at the math. The FET itself may be rated for 100A, but the rest of it, well, isn't.

[ThunderCactus]

Originally Posted by Scopedog

According to how the number of amps delivered are calculated with your current battery, you're discharging at a whopping 64amps.

The amperage in the motor is determined by draw, not by how much amperage the battery is capable of supplying.
You can run an airsoft gun off 80C 20,000mah battery as long as it's 2S or 3S

The overheating problem you're encountering is a common one with active braking SW-COMPs.
The active braking creates a LOT of heat in the motor, especially due to the fact you're using an 11.1v LiPo.
Quick consecutive semi-auto is actually creating more heat than full auto due to the increased frequency of braking.
I had the same problem on my M4 with a systema magnum motor. I couldn't get more than 30 rounds out before it gave me an overheat warning.

The solution for me was to use a really good motor. It took an eagle force EF1300 to get my M249 running without overheating. And I went through 3 motors on my M4 because the active braking kept damaging them.

You could probably send your motor in to get balanced, get the spring tension adjusted, and put better brushes in.

[CJay]

I'll maybe see if I can do something to be able to deactivate the active brake without double tapping in semi. Probs just switch to a custom large type 9.6v nimh probs the easiest thing to do.