Does motor temp affect performance?

[Dad1279]

Wouldn't the heat also cook the lubricant in the bearing/bushings? I have not had a CIM apart, but some destructive testing may be in order.

[joek]

we've never had a problem with overheating motors, but i've heard of overheating fisher-price motors, but never CIMs (and we're running off ones from '07)

[Al Skierkiewicz]

Any motor provided in the KOP, in any year, can be overheated through misuse. The FP motors are particularly sensitive to operating in an RPM range (low RPM) that does not allow the internal fan to cool the motor.

[DonRotolo]

Originally Posted by Joe Johnson

*I know some who argue that the thermal shock is too much for a motor

Well, the shock isn't much, considering the heat paths into the motor. But I have a problem with using so much freeze spray - it is mildly dangerous (as much as, say, WD-40) and isn't healthy to breathe. Instead, fans (such as those on Victors, or the larger ones in the KoP) can be mounted to blow air across the motors at all times, this will make a definite difference.

But, it is hard to argue with cold-in-a-can, I don't have anything that can compare.

Originally Posted by NC GEARS

I noticed that some of our battery cables were hot when we took them out of the bot as well.

This is not ideal; either the cables are damaged (if hot in spots only), undersized (if hot along their length), or have loose connections (if the connections are hot). This definitely affects the power the motors can see and use. Avoid bundling wires up too tightly; allow some space around them for cooling

Originally Posted by Dad1279

Wouldn't the heat also cook the lubricant in the bearing/bushings?

The grease used is probably good to well over 200C, the bearings don't get that hot. No worries there.

last year we were able to mount our victors directly under the CIM motor, the airflow helped keep it cooler. Then again, Lunacy was not hard on the drivetrain.

[sanddrag]

Originally Posted by Don Rotolo

Avoid bundling wires up too tightly; allow some space around them for cooling.

If the wires are heating to the point where they need cooling, something else is wrong. Circuit breaker not tripping, too small of gauge, etc.

[EricVanWyk]

Originally Posted by sanddrag

If the wires are heating to the point where they need cooling, something else is wrong. Circuit breaker not tripping, too small of gauge, etc.

Actually, I have to agree with Don here.

Take a look at http://www.powerstream.com/Wire_Size.htm - The rated currents for Chassis (unbundled) and Power Transmission (bundled) differ by about a factor of two.

Tight wire bundles can have an effect. I usually tell students to put it on the "nice to have but don't panic about it" priority level. I just don't recommend that teams put their entire power flow through those wire guides.

[Al Skierkiewicz]

For those of you that are interested, the tables that Erik has linked to are also derived from the National Electrical Code and in some locations, the NEC is the rule rather than local codes.
The transmission numbers derive from voltage drop in the wire for different currents. The desire is to have less than a specified voltage drop for a given wire length. This insures that your wall outlet maintains the 110 or 120 volt output when you plug in a toaster, space heater or hair dryer.
If Art Dutra happens to lurk by, he could be more specific than I on this subject.

[Damaku250]

Hm. After frying a CIM at Waterloo, me and a teammate were discussing something like this, and as paintballers we discussed the possibility of spraying liquid CO2 onto the CIMs after every match or so. Would this work? Or is there something special about the freez-it spray?

[Al Skierkiewicz]

Craig,
Freez spray or CO2 work by evaporating from the hot surface and taking some of the heat with it. Unfortunately, the heat is inside the motor, stored in the steel armature and windings and to a lesser extent in the case and magnets. If teams use this approach they must also be aware that making cold surfaces in Atlanta humidity will bring about condensation. Water may not be a desired effect if it drips into controllers or Crio.

[Joe Johnson]

Originally Posted by Al Skierkiewicz

Craig,
Freez spray or CO2 work by evaporating from the hot surface and taking some of the heat with it. Unfortunately, the heat is inside the motor, stored in the steel armature and windings and to a lesser extent in the case and magnets. If teams use this approach they must also be aware that making cold surfaces in Atlanta humidity will bring about condensation. Water may not be a desired effect if it drips into controllers or Crio.

Very good point. I recall that the motors can get a bit frosted if you cool them too much in the humid air of Atlanta. The good thing about the CIMs being a closed can I guess is that the water won't get inside the motor but you need to be sure not have any dew drops drip onto Victors, Jags, and/or crios.

Joe J

[Damaku250]

Originally Posted by Al Skierkiewicz

Craig,
Freez spray or CO2 work by evaporating from the hot surface and taking some of the heat with it. Unfortunately, the heat is inside the motor, stored in the steel armature and windings and to a lesser extent in the case and magnets. If teams use this approach they must also be aware that making cold surfaces in Atlanta humidity will bring about condensation. Water may not be a desired effect if it drips into controllers or Crio.

Shouldn't be too bad I suppose, we only have our pneumatics tanks around the CIMS...

What I meant was that the freez it seems to be "antistatic" or something, and I read on their site that it's non-frosting, so i was wondering how important these features were.

I figured if you attach a Co2 tank to the reciever valve and turn it upside down, you should get liquid as most tanks aren't anti-siphon.

[Joe Johnson]

Originally Posted by Damaku250

Hm. After frying a CIM at Waterloo, me and a teammate were discussing something like this, and as paintballers we discussed the possibility of spraying liquid CO2 onto the CIMs after every match or so. Would this work? Or is there something special about the freez-it spray?

Cool is cool.

The thing I like about the Freez-it stuff is that it comes out as a liquid if you hold the can just so and spray with the right velocity. This is important (or rather, nice) because it lets you direct the coolness right to the bits you are interest in.

For example, if you want Thing A cool, you drizzle some liquid out of the Freez-it (or equiv) and onto Thing A. Thing A causes the liquid to boil, which sucks heat out of Thing A like mad (it is a phase transition thing -- gobs of energy are required to go from liquid to gas).

I have no experience with CO2, but I don't THINK it comes out as a liquid but again, cool is cool. Expanding CO2 takes energy (though I don't know how it compares to the liquid->gas transition of Freez-it) and that energy comes from the surrounding environment. If you can control the CO2 such that you can get the heat out of a particular part or group of parts, it should work fine.

Joe J.

[Ether]

FWIW:

http://www.vapco.com/prod_freezeitspray.html

Freez-It contains menthol, camphor, eucalyptus oil, and isopropyl alcohol.

Menthol, camphor, and eucalyptus oil are mostly harmless in small amounts, but have a strong odor. Same ingredients are in Vicks Vapo-Rub that Mom used to rub on your chest when you had a cold (oops, am I showing my age?).

Isopropyl alcohol, unlike ethyl alcohol (the drinking kind) is toxic if ingested or inhaled in sufficient amounts. If you get an unexplained headache that should be a warning sign.

Get enough folks using that indoors and it may get banned. Although I suppose the venue at Atlanta is large enough it might hardly be noticed?

CO2, by contrast, is relatively safe, except for the stored-energy concerns.

If you've got enough room around your CIM, try attaching an aluminum or copper heat sink with lots of surface area (fins).

[Alan Anderson]

Originally Posted by Ether

If you've got enough room around your CIM, try attaching an aluminum or copper heat sink with lots of surface area (fins).

With or without the additional surface area, airflow is key. You want to get as much hot air away from the case as you can. The earlier suggestion of adding a fan is a good one.

[Ether]

Originally Posted by Alan Anderson

With or without the additional surface area, airflow is key. You want to get as much hot air away from the case as you can. The earlier suggestion of adding a fan is a good one.

Yeah, a fan is probably the first thing to try.

But the converse is true too: with or without fan-forced airflow, surface area is key. So if more cooling is needed, adding a heatsink could make a big difference.