Crawlmaster 13t running hot

[summerof95]

I just got a new crawlmaster 13t motor, with 6 degree advance timing, as suggested by Holmes.
I've run it twice now in my scx10, and both times I cut the run short when the motor hit 160.

FDR on the rig is 62:1, (.23 rollout).
I'm running 4s through Brxl, no Holmes hold.
I checked the gear mesh, and I cleaned and re-lubed the driveline. The chassis rolls freely without the motor.

I feel like it's getting way too hot. I can't really gear down anymore than I am...

What am I missing?

 

[JohnRobHolmes]

4s is a lot of voltage, it will be tough to keep temps down if you spend a lot of time near full throttle. Be sure your motor runs faster in forwards than reverse. Add more timing too, on 4s you will want 12 degrees.

 

[summerof95]

I was under the impression that increasing timing increases amps drawn, leading to hotter temps...
You're saying it's actually the opposite?

 

[allanon1965]

yes, advancing the timing up to a point will cool the motor, if JRH says 12 degrees, then thats what I would set it at.

 

[JohnRobHolmes]

timing is relative to motor rpms. The faster the rpm, the more timing needed to offset magnet field distortions. If the efficiency gain with better commutation angle is greater than your torque per amp change, the motor runs cooler.


Spending most of your time at low throttle and technical crawling would favor 6 degrees. Spending most to all of your time at full throttle will favor 12 to 24 degrees.




It is also the eventual reason to get a dialed off road brushless system.

 

[summerof95]

What effects would the increased timing have on the motor at lower rpms?
If running fast with low timing can lead to extra heat, can running slow with higher timing do the same?

 

[summerof95]

I've got it at about 12 degrees now. I left my TX on overnight, evidently, so now I need to wait a bit before I can test this out.

 

[4wdbowtie]

I've got it at about 12 degrees now. I left my TX on overnight, evidently, so now I need to wait a bit before I can test this out.

:lmao::lmao::lmao: I cant do that with my Tx. It beeps at me if i leave it alone for to long.

 

[summerof95]

Tested it today with almost 2 straight hours of running. All low-speed technical stuff. Temps stayed low.
I guess I just need to refrain from the occasional bombing around like an idiot.

 

[alexchen86]

I learned that the hard way lol. My original CrawlMaster was also 13T set at 6* timing on 3s.

What I failed to do was taking into consideration how much my Wraith at the time weighed. Sure I wasn't full throttle more than a couple of seconds tops but what really over heated the motor was weight of the rig.

All aluminum paneling, full aluminum custom hood, heavy aluminum CAC 2.2 beadlocks, aluminum tranny case, Robinson internals, SuperShafty top shaft setup to run a huge heavy Gen3 steel slipper, and of course all the VP aluminum goodies on the axles....not to mention the interior doesn't help with it blocking air circulation.

Motor temps are a little more difficult to get an accurate read being that you can only aim a temp gun from underneath the rig through the rear.

After that went with a CM 35T no issue at all for well over 3 years.

And yes always ask questions JRH is definitely the first person I'd turn to when it comes to electrical power systems...that's why over the years I think I must have purchased at least 6 -7 540 brushed cans from him, an old school new 10T cobalt Puller 500 he was kind enough to go out of his way to make me a new armature when mine snapped, 4-5 BRXLs, his new BLE Pro/TrailMaster 3300kv combo, and a few rebuilds here and there.

 

[summerof95]

A question came to me regarding the temperature readings from my first post.

HH recommends keeping the temperature below 160f, but doesn't actually suggest where the measurement is taken.
Since it's the internal components can can to damaged by heat (not the can), I took the readings from the shaft, as I figured that would be the closest I could get to the actual temp inside the can.
Taking a reading from the can itself will presumable result in a lower reading.

Where is the suggested spot to take a reading?


Second, someone had suggested that if the motor is overheating, but the ESC is staying cool, that it may be undergeared.
It that a real thing, or are they off their rocker?

 

[JohnRobHolmes]

160f is a can reading. The temperature rating of Pro motor internals is 400f, and sport and expert crawlmasters are 350f. The shaft is also a good point to read, but since it is reflective you may not get proper readings.


You can have extra heat on a motor that is undergeared, if it spins too fast for the materials used. I doubt that is your problem, but it would be great for your own knowledge to test slightly higher gearing and see how the system responds.

 

[summerof95]

Wow. Thanks for such a fast response.

If the shaft is 160 (contact measure, not infrared), then it's probably still well within a safe operating range, since the can was nowhere near that hot.
I feel a lot better about running the motor now, knowing that it's not going molten on me.

Thanks again!