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Does the ESC (without timing) affect the top end RPM?

Does the ESC (without timing) affect the top end RPM?

Old 03-17-2014, 11:47 PM
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Default Does the ESC (without timing) affect the top end RPM?

I've been puzzled with this question from time to time.

There's many settings on modern ESC's, but for this question, think stock class and blinky mode (no timing).

I have two motors and two ESC's and I think I'll measure max RPM with no load with both combos and compare.

I'm just wondering if others have done the same, and what you might have found out?

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Old 03-18-2014, 04:21 AM
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Originally Posted by Cole Trickle View Post
Does the ESC (without timing) affect the top end RPM?
Yes, but only a small amount. Almost all brushless ESCs use microprocessors, and these require a certain amount of time (called latency) to react to the incoming sensor signals and step the motor drive to the next commutation pattern. This time delay retards the timing. The higher the free-running RPM, the farther the timing is retarded.

If you're running VTA or 17.5 1s 1/12 scale, the timing isn't affected much at all. If you are running an 8.5T on 2s, then it will be much more noticeable.
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Old 03-18-2014, 04:39 AM
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Thanks.

I'm running 17,5, 2S.

I think I'll try measuring anyway, just for fun :-)
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Old 03-18-2014, 05:30 AM
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If your ESC has a setting called Throttle PWM (Pulse Width Modulation), that can affect top end, but to what extent I can't say. Higher PWM settings will deliver more RPM at the cost of higher heat in the ESC. You could try playing with that. I've messed with it on my Vipers and I can't say I've noticed much difference.
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Old 03-18-2014, 07:07 AM
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Originally Posted by klaymon View Post
If your ESC has a setting called Throttle PWM (Pulse Width Modulation), that can affect top end, but to what extent I can't say. Higher PWM settings will deliver more RPM at the cost of higher heat in the ESC. You could try playing with that. I've messed with it on my Vipers and I can't say I've noticed much difference.
PWM is only present at partial throttle. At full throttle, PWM ceases; the appropriate motor windings are driven 100% of the time. If a particular speed control shows a difference in full-throttle motor speed when the PWM drive frequency is changed, then there is something else (probably bad!) going on.
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Old 03-19-2014, 12:38 AM
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That makes sense, thanks :-)
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