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Old 04-08-2010, 04:29 AM   #1
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Default Freezing Motors

I was wondering do you guys still try to freeze your brushless motors before a race. Also what are the advantages of doing this? Thanks
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Old 04-08-2010, 04:58 AM   #2
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I was wondering do you guys still try to freeze your brushless motors before a race. Also what are the advantages of doing this? Thanks
A guy reported here on rctech that there was an epidemy of BL motors failures at his track ( was it 0r8ital orSyndr0me? dunno)

If I remember well the epidemy was tracked down to the Pelletier effect coolers used by everyone, which apparently caused condensation inside the can and maybe even a kind of thermic shock, causing the failures. The guys stopped using the Pelletiers and the failures stopped. But that was at the time of pre-SPX speedos, with huges rollouts so I don't know what it would be now.

A very good guy at my track uses one but just 5 minutes before racing, just to delay the smothering of the motor a 4'30. He says he starts with a cool motor, but not quite cold. No problem yet.
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Old 04-08-2010, 05:20 AM   #3
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the safer, and in general "preferred" way to keep a motor cool is to use a fan from what i've seen.

The peltiers were possibly used more for brushed motors, but don't quote me on that...
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Old 04-08-2010, 06:03 AM   #4
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In brushed the pelletier helps preventing the magnets from fading but if too cold with a high rollout, the risk of breaking them from the thermic shock is quite high.
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Old 04-08-2010, 08:17 AM   #5
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All I do if I am worried about temps before I race is make sure the motor is at the ambient temp. I have a small fan in my pits that brings the motor temps down fairly quickly after I run. This comes in handy during practice because I can get back on the track quickly...less than 10 minutes in most cases.
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Old 04-08-2010, 09:58 AM   #6
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Is it still necessary to run motors so hot? One of the quick guys down at our track (carpet) was telling me that his motors never get near the manufacturers maximum. Is this generally true? It would seem to me that a hot motor is not being very efficient but then again it doesn't take too much energy to heat up something the size of a motor to red hot.
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Old 04-08-2010, 12:37 PM   #7
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Freezing motors was definitely a brushed motor thing. Since we were running the motors VERY hard and gearing VERY high (especially at big races), freezing them started them off colder and took a bit longer before they got really hot. Motor temps of 200+ were common after a run (even with freezing, a heat sink and a fan). Brushless motors really don't benefit from this as the motors are more efficient and motor temps are usually kept down to 140-165 depending on the mfr. Also, the ESC's are doing most of the hard work and so gearing is usually REALLY low for punch.
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Old 04-08-2010, 02:02 PM   #8
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I use component freeze or you can use dust off upside down.I used it all season last year with no issues but plenty of rip dont try to use at nightime when it is cool just very hard to handle if you are running a 13.5 tc
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Old 04-08-2010, 02:47 PM   #9
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Quote:
Originally Posted by Finite Racing View Post
Is it still necessary to run motors so hot? One of the quick guys down at our track (carpet) was telling me that his motors never get near the manufacturers maximum. Is this generally true? It would seem to me that a hot motor is not being very efficient but then again it doesn't take too much energy to heat up something the size of a motor to red hot.
No.

It's interesting that a lot of (mainly) US racers keep going on about changing gearing until it gets near it's temp limit, i.e. gear by temp.

It's far better to gear by lap times and keep an eye on the temps in case they get too high.

As has been shown in some cases, using a modern ESC can lead to overtiming the motor which causes failures before the motor even gets very hot.

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Old 04-08-2010, 06:51 PM   #10
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Today with the added dynamic timing in the program ESC, brushless motors
are heating up after a race coming off the track.
Building up heat.

Most racers are using the coolers after the race and not before.
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Old 04-09-2010, 06:34 AM   #11
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Quote:
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Today with the added dynamic timing in the program ESC, brushless motors
are heating up after a race coming off the track.
Building up heat.

Most racers are using the coolers after the race and not before.
Proves the point about the heat being in the motor internals and fans etc not really cooling the parts that truly need it.

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