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Old 09-22-2011, 10:20 PM   #1
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Default Is it just heat to worry about?

Pushing a motor to high RPM's what am I risking? Say I run 4s on a motor that's recommended only to 3s. Please explain??
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Old 09-22-2011, 10:59 PM   #2
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Pushing a motor to high RPM's what am I risking? Say I run 4s on a motor that's recommended only to 3s. Please explain??
Aside from the heat melting the epoxy holding the coils together or melting solder joints within the motor there's the problem of mechanical failure. From what I understand, a brushless motor's rotor can be spun at RPM rates so high that it will literally be torn apart by centrifugal force.
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Old 09-22-2011, 11:09 PM   #3
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Pushing a motor to high RPM's what am I risking? Say I run 4s on a motor that's recommended only to 3s. Please explain??
The 2 main issues are the mechanical properties of the materials used to manufacture it, the higher the rpm the greater the stress on materials, however, motors are manufactured to higher tolerances than the companies claim, to make them more reliable, so, you can assume with little confidence say 25% over the high rpm mark of a motor, before you reach the inherent physical limitations of the motor. And by little confidence, i mean VERY LITTLE.

The other is heat, high revs equals more friction equals more heat. So if you are going to over rev the motor, heat sinks and fans are a must. Again, this is dependent on how long you are running for, short speed run, heat is not such an issue, so ramp it up, but for a 10m main, heat is going to be a huge issue.

If you are unsure about what you are doing, use HobbyKing motors and see how far you can go before they self destruct, 30 buck motor being destroyed is much nicer than 180 buck tekin.
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Old 09-22-2011, 11:19 PM   #4
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The 2 main issues are the mechanical properties of the materials used to manufacture it, the higher the rpm the greater the stress on materials, however, motors are manufactured to higher tolerances than the companies claim, to make them more reliable, so, you can assume with little confidence say 25% over the high rpm mark of a motor.

The other is heat, high revs equals more friction equals more heat. So if you are going to over rev the motor, heat sinks and fans are a must. Again, this is dependent on how long you are running for, short speed run, heat is not such an issue, so ramp it up, but for a 10m main, heat is going to be a huge issue.
Ok great. So running at 4s for short periods shouldn't hurt it... Much. My esc can only handle 3s so as of now that's all I will be running. Unless the same holds true for the esc. I ha e seen people run the Traxxas Velineon on 4s. I am going to run crazy gearing. The heat Im not terribly worried about because I am only doing this to see what types of speeds I can achieve. Not doing any race heats. I did however buy the biggest heat sink I could find that will fit my chassis.
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