RC brake cut off function?

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deronmoped   10 kW

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RC brake cut off function?

Post by deronmoped » Mar 22 2017 12:50am

I hooked up my brake cut off switches to the power supply for the servo tester. It works, but the motor cut off is delayed. Instead of guessing has anyone addressed this already and knows where to cut off the motor instantly?

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amberwolf   100 GW

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Re: RC brake cut off function?

Post by amberwolf » Mar 22 2017 1:00am

At a guess, the ESC you're using responds to losing throttle input only with a delay.

Does the ESC have an actual direct brake function? If so, perhaps it is a faster response using htat.

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Re: RC brake cut off function?

Post by deronmoped » Mar 22 2017 9:36am

Brake function on the ESC, I will check. This is my first RC build, so all this stuff is new to me. Is there a RC tutorial?

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Re: RC brake cut off function?

Post by deronmoped » Mar 22 2017 1:03pm

I looked into the brake function on my ESC, it will only stop the motor from spinning. This is used in the RC airplane world to either let the prop windmill or not windmill. On my Ebike build, this will not do anything, as the motor is not engaged when slowing the bike down. The motor is not fixed to the drive, it drives in one direction and freewheels in the other direction.

What is happening right now, is the ESC detects my brake switch (on my bike) cutting the power off (signal loss from servo tester) and waits 1 second to lower power output. After 2 seconds the power will be completely cut off.

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Re: RC brake cut off function?

Post by amberwolf » Mar 22 2017 1:58pm

deronmoped wrote:I looked into the brake function on my ESC, it will only stop the motor from spinning. This is used in the RC airplane world to either let the prop windmill or not windmill.

Ah. Then for an elecronic cutoff, what you need to see is if the ESC has a throttle input mode that will cut power immediately, and not slowly reduce it.

Or see if it is programmable, so that you can change the time to reduce to zero power.

On my Ebike build, this will not do anything, as the motor is not engaged when slowing the bike down. The motor is not fixed to the drive, it drives in one direction and freewheels in the other direction.
Since it freewheels, then you could actually use the existing brake function, as when it locks the motor it will then simply freewheel--but presumably it will do this instantly rather than on a delay.

If it also has a delay, and is not programmable, then the only way I can think of to cut power instantly is to have a big fat power cutoff switch to remove power from the ESC (but to do this while it's drawing any power takes a big arc-proof switch.

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Re: RC brake cut off function?

Post by deronmoped » Mar 23 2017 9:30am

I looked at the page that came with the ESC and it does not look like there is a program for "loss of signal".

Yeah, I was thinking of a heavy duty cut off for the battery power. I'm also contemplating a dead man's cut off switch.

One thing I'm going to try is, getting the servo tester to think that it's pot has returned to zero, with the brake switch. By either, opening the wiper leg, or by, shorting the wiper leg to zero with the brake cut off switch. I will have to diagram the servo tester circuit to see what might work.

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Re: RC brake cut off function?

Post by deronmoped » Mar 25 2017 9:43am

I found the solution.

On the servo tester, there is a pot that controls the speed. With my servo tester, putting the brake switch (normally closed switch) between one of the "fixed" legs (leg of the pot "without" the wiper) will cut the motor immediately.

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