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Help with an EV circuit for a quad cycle

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Hello All,

My friend and I are converting a quad cycle used to carry pizza boxes into an EV. While building the circuit for the motor, battery, motor controller, and throttle, we ran into an issue that we do not know how to fix. When the circuit is connected, and the battery is turned on, the motor surges and then immediately receives no current. Here is a video of it happening and also photos of the 4 individual pieces:

Motor Controller:




For the battery, the bottom black piece is to connect it to the circuit, it comes unattached and is charged individually.

The battery has been tested with the motor without a motor controller or throttle and it runs at full speed. The motor has been tested with another battery and runs at full speed. The throttle has been tested on another bike and works properly - on our circuit we have yet to have it work at all. The motor controller is the only thing we haven't tested individually, so it possibly could be the issue. The very first time we connected everything, the motor ran at full speed (like there was no motor controller or throttle) but has not done that since. We are not sure what the problem is. Maybe someone could give some theories or suggestions? The motor controller is in Chinese so we don't know exactly what goes to what, but the throttle we have has 3 wires and the motor controller only had one option with three wires (also they were both bought from the same company and was actually labelled "throttle" in english). However this does not appear to be working.

Any thoughts? Suggestions? We are stumped and not really sure what is wrong.

Thank you,

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746 Posts
Below is a pic of a wire diagram for a YK-31 (24V 500W) brushed speed controller

These are the necessary connections

Thick Black & Red = connect to 24V battery

Thick Yellow & Blue = connect to the motor

Thin Red & Blue = connect to key or toggle switch (for speed controller on/off)

Thin (3) wire throttle plug = connect to throttle (red = power in, black = negative, blue (or other color) = signal)

The others are optional

...a charge connector (to attach a battery charger)

...a brake cut-off switch

...a pilot light (?)

...& a brake light (to turn on a brake light when the brake cut-off switch is activated)


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