Cooling v5 motors

There has been some debate among the Vex community as to how to cool the v5 motors. Is cooling the v5 motors with compressed air coolant bad for performance? and why or why not?

Spraying compressed air on a regular motor usually only cools down the plastic case, and does nothing for the actual motor that’s inside. I’ve found taking apart the case and putting the motor parts in front of a fan for a minute or two usually does a better job. Though, quick swap is usually always the better solution.


it’s not bad for the motors if you use it properly, but it’s also not very effective. It mostly will just cool the plastic shell of the motor housing, and do very little to cool the interior.

Quick swapping motors is much more effective, however it’s often not an option since it requires extra motors and easy motor access.

if your motors need frequent cooling then you should probably try to remedy the cause of the overheating first.


I had heard somewhere that spraying compressed air coolant freezes the grease inside the motor causing loss of preformance… Do you know the accuracy of this?

I’ve never had that happen, but it sounds possible if a large enough amount was sprayed on to actually affect the motor under the casing.
Not my expertise, but maybe the grease freeze is only temporary, and the motor returns to its normal efficiency after some use.

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The only reason I ask is because I’ve never seen a v5 motor catch fire but I know at 50C vex limits motor performance. I was wondering if someone knows where the sensor is so we can cool that.

Attempting to bypass your temperature sensor is a really bad idea. It puts you at risk of permanently damaging your motors an possibly catching on fire (like the cortex systems of old)


I know another team which puts their motors in the fridge to cool them down.


Yes, it is definitely a bad idea…but still an idea none the less

I’ve never heard this before… So do they bring a mini fridge to comps or smth?

Personally I have seen teams with bags of ice they place over motors but I don’t know how effective that is

Interesting… What does your team do?

I know they use a hair dryer at comps.

I think they use a regular fridge when they have access to one, like at school (they can use the teacher’s one).

We have used cooling spray in the past but like mentioned earlier the best way to cool a motor is to quick swap it. However, the cases where you should have to quick swap should be rare and you just shouldn’t have mechanisms that over heat motors, especially if you get hot after a single match


I am going to go on limb here - a well designed robot should rarely have motors overheat. As others have mentioned, reducing the load on the motors can be done through better build quality (avoid friction) and proper gearing. Yes your mechanism might go slower but it should be able to handle back to back matches.

as for solutions I have heard, I am not quite sure you need to bring a refrigerator to events. Compressed air cans sound fantastic, until some kid on the team makes poor decisions, like spraying team mates. It is a safety hazard. Quick swap seem to be a good solution, not just for “overheating” but components do fail from time to time. A good robot design allows for easy maintenance.

Now for the original poster, are your motors overheating all the time? then that is probably a design flaw, just spraying it to cool it down does not solve the root cause, just masks the problem and you could still have a catastrophic failure during a match. Best analyze the problem more deeply.


I agree with you and if you look at my original post I said you shouldn’t overheat motors at all


I was more concerned about not going more on spray cooling motors, as it seemed to be OPs only idea.

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I agree that although spray cooling looks cool the results don’t back it up

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Already stated here by others, but I’ll say it again. If a motor is overheating it is operating to close to its upper torque limit (stall torque). Change your gearing to provide more torque and perhaps program in some safety catches for when your motor is too heavily loaded. If you are counting on cooling your motors between uses, you are going to have a bad time.

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In our current design the motors overheat after about 3-5 minutes of continuous use(easily enough to last a full match). Imo its ok because our goal is to have a robot that pushes the upper limits of the hardware to be as competitive as possible… While adding gearing would reduce load, it also reduces speed which is the opposite of what we want.