What affects motor ESC temperature?

[Indra]

Hey everyone! This next one is gonna be a newbie question, any input would be greatly appreciated!

I'm currently starting a Wraith build. I bought a Tekin 13.5T motor, and a Mamba Max Pro ESC, in hopes that the Wraith will have more speed and OK crawlability. The store guy where I bought the combo gave me a weird look, he said "are you sure you wanna put them in your Wraith?" he said with the stock gearing, I will make the ESC and motor hot and eventually will break them.

I browsed through some forums, and learned about the basics of gearing ratios. So far I kind of get it. I think the topic on gearing is mostly about temperature.

In this forum, @Harley suggested that if use the above combo, I should use the stock gear ratio 4:1, but change the pitch from the small 48p to a bigger 32p. So with Axial spur gears and pinion it is a 54T spur and a 13T or 14T pinion. That should take care of the temp issue.

My question is, what factor increases the temps? is it the speed of the running motor, or the weight or torque of the motor?

I believe the answer to this question is our reference to tune the gearing

Please help a newbie out :-)))) or correct me if I'm asking the wrong question for this issue.

Thanks in advance!

[Olle P]

Temperature of the ESC shouldn't be much of a problem for you.
- The ESC temperature goes up due to power being used in it, and that stems from current drawn from the internal BEC and current drawn by the motor.
- The internal BEC might be at high load if you use it to feed the steering servo, which is why most crawlers use a separate feed to the servo. (External BEC or straight from the bettery.)
- Motor current depends on motor load and battery voltage. With higher battery voltage the motor will draw more current at higher speeds. The motor draws more current when more torque is needed, and that's where the gearing comes into play. With a higher gearing ratio the load will be lower.

Since the MMP is designed to handle high voltage batteries and motors more starved for current than your's it shouldn't be a problem.

The motor might get hot though, unless you get the gearing ratio high enough. Combined with a high voltage even the right gearing might not be sufficient, but some additional cooling of the motor can be required.

[Indra]

Originally Posted by Olle P

Temperature of the ESC shouldn't be much of a problem for you.
- The ESC temperature goes up due to power being used in it, and that stems from current drawn from the internal BEC and current drawn by the motor.
- The internal BEC might be a.....

thank so much for the info!