Motors Getting Too Hot - Recommendations?

[the.ronin]

I've got a Yeti Jr carrying a lot of extra electronics (FPV system, GPS, OSD, walkie talkie internals) which along with a 2S 2000mAh lipo, weighs a total of 2 lb 15 oz (or 1.3 kg).


I've upgraded the ESC and motor to a 25A Tazer Mini ESC and a Fuze Mini 4500KV brushless motor.


After a good run, the motor temp is reaching 240F. I believe I had read somewhere that optimal temp was 160F. I have swapped the pinion gear from the stock 16 tooth to a 14 tooth. Of note, I also have my throttle limits set to 50 because I am not going for speed but more control and rock crawling.


Do you think I need to go lower KV motor? Or try heat sinks first? Any suggestions appreciated. Thanks.


[edit] I would add that after a while of running hard, the motor will just cut out. I don't know if this is a temp cutoff at the ESC? Because I can still steer and everything else works fine. If I power cycle the ESC, the motor will work again regardless if I waited for it to cool down. Not sure if it's just me, but this motor shutdown seems to particularly get triggered when I'm at a stop and go in reverse. Then when I try to go forward again, it's shut down.

[Jboucher]

4500kv is wayyy overboard for Crawling...

You need something like sub-2500kv I would say.

I just got my revolver 380 from holmes, if you don't mind the noise, it's perfect for crawling.

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[the.ronin]

Thank you Jboucher.

So even for this 1/18 scale, sub-2500kv is the way to go? Again, I'm running super fat I think at nearly 3 pounds.

[edit] I actually thought I was being conservative at 4000kv. Various posts and youtube videos about upgrading the Yeti Jr motor show folks using upwards of 7000kv.

[Jboucher]

Well im using 2s on the stock 40T brushed motor and I flip the truck every time I turn too fast

It has aluminum beadlocks, bigger tires and all the possible aluminum parts from GPM Racing.
I have the 3d print battery tray to move the LiPo in the middle and the ESC is in the back.

I can't see how the hell you can control the truck at 4500kv much less 7000kv...

Plus using 4500kv and cutting throttle to 50%.is kinda the same thing as using 2000kv at full throttle no ?

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[Jboucher]

Crawling means walking speed or even less

Lower kV, higher voltage is what you need for control and torque

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[durok]

Your motor and ESC will accept 3S...

You could try going up in voltage and then gearing down as far as you can, use the smallest pinion that will mesh well.

Brushless motor kv ratings tend to be different for smaller motors than for bigger motors.

I don't think that you are necessarily running too high of a kv...

For example, my Associated DB8 Nomad 1/8th scale buggy weighs over 8lbs, uses either 3S or 4S, and runs a large 2000kv brushless motor.

It hits around 40mph with that low of a kv rating!

[the.ronin]

Thanks again everyone.

Originally Posted by Jboucher

I just got my revolver 380 from holmes, if you don't mind the noise, it's perfect for crawling.

This actually looks perfect for the Yeti Jr with its 2mm shaft diamater. What did you install this on if you don't mind my asking?

[Jboucher]

Originally Posted by the.ronin

Thanks again everyone.






This actually looks perfect for the Yeti Jr with its 2mm shaft diamater. What did you install this on if you don't mind my asking?

Not installed yet
It's going to the yeti jr rock racer with a hobbywing 16BL30.
If it's not smooth enough, I will buy a mamba micro x

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[Electroz]

Super late to this thread, I know. I just ordered a 16bl30 and a small outrunner to go with it. How did you find the performance of the hobbywing? There is almost zero real-world information available online.