# Ebike brake lever cutoff switch / interrupt switch : How does it work?



## maarten_almighty (Jan 11, 2020)

Hi all,



When pressing the brake lever on my ebike the bldc motor controller (aka ebike controller) 'cuts power' to the motor until the brake lever is released again/sensor is deactivated. I would love to know how that works/what happens.
I am wondering what causes the power to be 'cut off' when the sensor is triggered by pressing the brake lever. My theory is that the power (5v +) to the throttle and pedal assist sensor are cut off when one of the brake sensors is activated, this in turn causes the user to be unable to 'apply throttle' .
Perhaps my theory is way off, do any of you know how this works? Does it differ per case/controller ? Or is the method (of cutting off the power when one of the brake sensors is activated) quite universal ?


The controller I'm using: https://a.aliexpress.com/e1R175D8X
My battery: 20s 72v 10parallel  



I am trying to troubleshoot my ebike which does nothing when twisting the throttle.. 
PS: The bike also does nothing when connecting the 'self learning wires' together, which is strange, since I believe that should cause the motor to start rotating when the controller is turned on regardless of if there is a throttle installed/if the brake sensor is activated or not (not entirely sure about that last part about the brake sensor...).
The battery is directly connected to the controller (bms has been bypassed) so the bms is not the issue, battery is properly charged and also with the charger connected directly to the controller the bike appears to do nothing (no throttle response), so battery is not the issue. Power lock wire (wire that I connect to the positive side of the battery appears to be in good condition. 
I measured the voltage on the red/black ('power') wires going to the throttle and there is no voltage across them, which (assuming the controller is indeed turned on) makes me think the brake sensor wires may have a short circuit somewhere, which would cause the controller to 'think' the brake levers are being pushed which might be the cause of my issues.

The bike has been acting up for a few weeks now, normally when i flip the switch the bike works immediately (as soon as the switch is on there is throttle response). Lately there have been a few times where the bike took some time to 'start up' (I had to wait 3-5 seconds after flipping the switch before the bike started doing something (aka before there was throttle response). And now it has stopped working completely. 

What might be the issue? What checks could I perform to narrow it down?


Thank you very much for any input, it is greatly appreciated!


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