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  • June 27, 2022, 05:22:55 PM

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Author Topic: Brake drain on amps?  (Read 545 times)

Offline Dennis Toth

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Brake drain on amps?
« on: August 29, 2020, 05:57:43 PM »
Just a technical question about using the high brake setting on the Castle Creation ESC's (or any ESC). Does using the high brake function draw a lot of amps to hold the prop during the landing glide?

Best,    DennisT

Offline pmackenzie

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Re: Brake drain on amps?
« Reply #1 on: August 29, 2020, 06:02:05 PM »
Brakes are done by simply shorting out the motor windings, so no real amp draw from the battery to do this.
Full brake = full short. Softer braking pulses the short circuit off and on.
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Offline Dennis Toth

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Re: Brake drain on amps?
« Reply #2 on: August 29, 2020, 07:08:45 PM »
Pat,
Thanks, good information. I like to have the prop stopped fully but sometimes am close on battery headroom. Now I can apply full brake.

Best,   DennisT

Offline pmackenzie

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Re: Brake drain on amps?
« Reply #3 on: August 29, 2020, 09:01:41 PM »
They can still slowly spin on "full" brake.
Braking torque is proportional to current, which if shorted is proportional to the motors back-EMF.
At zero RPM there is no back EMF voltage, so no braking force. Motor spins a bit, starts to generate voltage and then braking force increases.
At some low RPM braking force will be equal to the torque from the prop due to aerodynamics and it stabilizes.

(Actually approaches it from the other direction for us, but same idea applies)
MAAC 8177


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