[Al Skierkiewicz]

Originally Posted by Max Lobovsky

Why is it that people keep saying that? Even at a reasonable load, the motor can easily be outputting 100+watts of heat. Even if the motor can radiate that safely itself, it is going to be hotter (significantly) than if it had some active cooling. Now say you do have a short spike in heat output. We can all agree that we would much rather have their cooler motor to start with spike, then the hotter one.

Sure its a bad idea to rely soley on cooling in your design to protect your motors, but you can definitley get more out of your motors if you cool them.

Max,
Run some numbers and I bet you find that the CFM of the fan vs. the radiating effectiveness of the motor case cannot get rid of 100 watts. (actually, if you are running the kitbot trannys then it is more like 250w/motor @ 40 amp input) If you blow air on the wire end of the motor (this is the end with the brush assy.) you may reduce the case temperature a little. If you were to add cooling fins and fan, you might be able to get the outside of the case down to ambient but there is no direct thermal connection to the armature where much of the heat is generated. If you end up far enough under wiegth to add fans, my bet would be on blowing them at the wire end of the motors. It might not do much, but if it makes you feel better than do it.