Castle Holdings LLC -- our motor production facility

[lincpimp]

Since we are discussing motor designs I have a few questions...

I had 2 of the old feigao xl can motors. 2 pole and cheap!!! I had a 14xl that I ran on 8s, and a 7xl that I ran on 4s. In the same weight vehicle with the same gearing (thus load) the 14xl ran cooler.

I am guessing the motors use the same materials and construction techniques. Are lower kv motors more effecient just due to design? Higher turn motors use thinner wire and more of it, is that inherently more effecient?

Just wondering. The 7xl was very gearing sensitive to keep temps down to "reasonable" levels. while the 14xl did not seem to mind. Amp draw must have some bearing, as less amps means less heat.

[sikeston34m]

Originally Posted by lincpimp

Since we are discussing motor designs I have a few questions...

I had 2 of the old feigao xl can motors. 2 pole and cheap!!! I had a 14xl that I ran on 8s, and a 7xl that I ran on 4s. In the same weight vehicle with the same gearing (thus load) the 14xl ran cooler.

I am guessing the motors use the same materials and construction techniques. Are lower kv motors more effecient just due to design? Higher turn motors use thinner wire and more of it, is that inherently more effecient?

Just wondering. The 7xl was very gearing sensitive to keep temps down to "reasonable" levels. while the 14xl did not seem to mind. Amp draw must have some bearing, as less amps means less heat.

The 14xl had two things going for it that the 7xl did not have.

#1. Lower kv - more torque to overcome the the mechanical resistence.

#2. Higher Voltage - This goes back to the Watts = Amps X Voltage law.

Think of it this way. It takes X number of Watts to accelerate the test vehicle. Less Amp Draw equals less heat.

The 14xl was taking advantage of the higher voltage, thus the amp draw was substantially less. Probably 50% of what the 7xl was drawing to do the same amount of work.

[nuz69]

Theoretically no. The 14XL has necessarily THINNER windings, therefore the windings heats more than the 7XL for the same amp. The thickness is lower as the turns is bigger, or the Kv lower (same space, longer windings ==> thinner windings). So theoretically a 8S 14XL setup will produce same heat than a 4S 7XL setup.
For example, a 1515/1Y and a 1515/2Y, both 4S. The 1515/2Y will run a lot hoter in current buggy or truggy setup. The 2Y needs higher voltage (8S) to run efficiently. But therefore, the resistive losses are smaller in the ESC, but you need a 8S ESC...
Higher Kv means less torque per amp (torque said alone means nothing).
Maybe, when the windings are thinner (14XL) they better fulfill the motor ? Just weight your two motor and see wich one is heavier ?