Voltage VS Motor temps
 

I have read in the past that going up in voltage will bring motor temps down on the same gearing. I'm not sure I understand how this would be possible or even if its true, but I just finished a Nirto to E conversion and had a different question.

Currently in my LST2 I'm running 5s with 28t pinion and 63t spur. Top speed according to "scriptasylum" my speed is 38.2mph (which is very close to what I GPS'd). For the lipo voltage I selected 4v/cell.

Question is, if I were to go to 6s and change the pinion to 25t, the calculator states a top speed of 40.93, so close to what I'm at now. How would that affect my temps? Up in voltage but down in gearing for similar speeds.

Thanks all! If I need to clarify anything let me know.

Root of my questiong is, would it be a good idea to buy another battery?

The higher the voltage, the less amps the systems draw. This all means the system has to work less.

So whether I change gearing or not, theoretically my temps will go down slightly?

Highly unlikely that higher voltage with same gearing will run cooler, far more likely to run hotter. Even with the same motor geared lower the motor temps will likely be higher. While the top speed might be close the higher voltage will have higher power capability getting there. Caveat is the way brushless motors react to gearing, and driving style so it’s difficult to be absolute.

Only true is the load is changed. Same load, higher voltage drives more amps.

Gearing can help some, but generally the best way to realize the potential benefits of higher voltage is to also change to a lower kv motor.

This is what I suspected at first. My motor temps are not in the danger zone by any means, maybe 130 tops, I just like to keep them in that range. As far as kv I'm already running a fairly low 1480kv motor. Anyway, I'll play with it a bit and see what happens.

Thanks for the responses!

Great thread, answered a question I had also.

Awesome! Glad it helped!

The system is only going to draw what it needs/can so by upping the voltage you are reducing the strain so it will run cooler

Nope, not unless the load is changed. Quite a few variables (motor efficiency/target speed/load etc), but with those all being equal, the higher voltage setup being more efficient (run cooler) is only true with a lower kv motor. If he simply gears down with the same motor to keep the same speed but raises the voltage, the motor would be over-revving and out of its efficiency range, creating more heat, an exaggerated example would be gearing a 3.5t at 8v for 20mph on a TC. That same motor would theoretically run cooler geared for 30mph at 6v. There's a more generous sweet spot with lower kv motors, but the principle stands. What his setup will do exactly depends on where in that spot he is currently at, and how much he changes a variable.

I say mess with it until you find the spot you are happy with, those temps are way better than what I usually run my stuff to.