RPM and rollout question/decision help?

[simplechamp]

The way I see it the higher kv setup would have the smaller load (lower gearing) and the lower kv setup would have the larger load (higher gearing). So I understand the lower kv motor might have more torque, but it also has a bigger load applied. The higher kv motor has less torque, but it has less load too. If you look at the rollout numbers the lower kv motor would be doing an extra 36% more "work" per revolution than the higher kv motor. For each revolution it's turning the tires further by 36% so I'm not sure if the extra torque will really do much besides cancel this out, if it will even do that.

It will take a given amount of power to make the vehicle go a certain speed (for example 1000W to go 40mph) and the battery voltage is staying at 14.8V for both motors, then each motor should draw 68A to run the vehicle at 40mph. That logic seems to say that it shouldn't make much difference which motor is used.

[nuz69]

Exactly, the difference will be on the bearings AND the better efficiency of the real neu AND the higher self inductancy of the widdings of the lower kV (which result in a better controlability), what I am saying from the beginning ^^

[What's_nitro?]

Originally Posted by simplechamp

It will take a given amount of power to make the vehicle go a certain speed (for example 1000W to go 40mph) and the battery voltage is staying at 14.8V for both motors, then each motor should draw 68A to run the vehicle at 40mph. That logic seems to say that it shouldn't make much difference which motor is used.

If both motors were equal in all aspects except for kV, then that statement would be 100% true. Unfortunately, they differ in lots of ways: weight, overall efficiency, overall design, parts used, etc. While each difference may be small, they are all present at all times.

The motor with the higher kV will be less efficient at the same (vehicle) speed as the lower kV. The motor that weighs less will make the vehicle more efficient overall. A higher motor speed imposes lower mechanical efficiency on the motor, as well as lower electrical efficiency.

Based on all that, I would chose the Neu 1512 1.5y. The lower kV will help motor efficiency, and the lighter weight will help overall vehicle efficiency. If you are only gearing for 40 mph I don't think you will notice any difference in driveability, either.