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36V 750W ebike controller install

I try to install the 36V 750W controller (Order# 80888). Its Wiring Directions state the Thin Purple cable sets Power On/Off. My Chinese upgrade kit worked for 4 years until its controller broke. My Power cable has the same plug and connects fine, but it does not have a Power On/Off cable connected. Does that mean its power remains on? (The Chinese upgrade kit did not come with a switch, so I deattach its power cable to switch it off.)

My ebike has two brakes. I used its connected black and connected red cables to switch off its motor when using a brake with the old controller. Do I connect them now to "Brake (low)" or "Brake (high)"? What does low and high mean for the wiring directions anyhow?

My throttle has a thick black cable with a white connector at the end with blue, white, and red cables plus two black connectors one with yellow and brown and the other with violett cable. I never got its green (full), yellow (half), red (empty) LED to come on or its red button motor on/off switch to work. There are two white three cable connectors. Is the black, green, red cable one for the throttle? (Or the blue, black, orange one?) Too bad both cable and connector have male plugs, so I need to switch one to the female plug of the old controller...

How could I use the "Three Speed" Wiring Direction? Can it increase/decrease the ebike motor speed with it? Do you sell a switch which I could attach to the handle-bar? Do you also sell the white tree cable connector which I need for the throttle control?

The Chinese ebike kit never specified name or specification if its motor. It is large in the back wheel center of the ebike and it is likely 500W. Do I need to be afraid that tthe 750W controller burns the motor after a while?

The Wiring Directions ( specify to connect the "Power" with Thick Red, Thick Black and Thin Purple cables. My LiFePO4 36V 20Ah battery provides both thick cable connections. I bought the 36V 500W ebike motor conversion kit from sannykung in 2010. So the 36V 750W controller should work! How to connect the thin purple cable? Ground like the Thick Black cable? 36V like the Thick Red cable? Or +5V from the Throttle Red cable? Sorry, I need more help than this one page Wiring Directions...
To make the controller continuously "on" the thin purple wire should be permanently attached to the thick red +36V power wire. This should make it emulate the original controller as you described.

The brake "low" and "high" wires are for activating electric brakes which are built into the controller. When these wires are connected through a switch to ground they will activate electronic braking which will enhance the friction brakes ability to slow down and stop the electric bicycle. You could wire the brake switch to either the low or high wire. The low wire will give a lower amount of electric braking power than the high wire will. You may need to experiment with this to figure out which one should be used with your bike.

Unfortunately I do not know what the bikes existing throttles wire functions are. Most throttles are wired differently from each other and the wire colors are not universal. Without having wiring directions for the existing throttle I could not know what the functions of the wires are for.

The three speed function of the controller is for controlling the top speed. It can be used with any SPDT switch to control the top speed of the controller. We currently do not have a handlebar mount SPDT switch but we do have a panel mount switch which is item # SWT-154 located on this page:

We have throttles with built-in three speed switches which are item numbers; THR-126 (Gold), THR-127 (Red), and THR-128 (Blue) that are available on this page:

Using a 750 Watt brushless controller with a 500 Watt brushless motor should not present any major problems. If the motor is used hard it may run a little hotter than it would with a 500 Watt controller, but as long as the motor does not run too hot then it will be fine. If it does start to run too hot then simply lower the amount of throttle that you give it when going uphill.

Due to this forum posting I recognize the need to update the wiring directions for the 36 Volt 750 Watt brushless controller item # SPD-36750BRUSHLESS. The updated wiring directions are located at this link:

How to wire the thin purple power wire to turn the controller on is now addressed in the notes section of the wiring directions.

I tried to get a local e-bike store to repair my assembly. Both only repair their own ebikes and only under warranty. So I installed an Amazon 36V 500W 26 inch rear wheel kit instead ($260), where connectors fit. For existing battery and brakes, I used my soldering iron plus isolation tape instead of official connectors. My updated ebike works better than it did under its previous ebike kit. It still doesn't have an on/off switch. Increasing its top motor speed from 15 to 23 miles/hour is not legal. But I hope the police remains quite as long as I bring my driver license plus remain within 5 miles/hour within the 20 miles/hour Utah ebike speed limit.

Thanks for the update and great to hear that you got your electric bicycle running again. I am not sure if an e-bike store that only repairs their own bikes under warranty is a good electric bike repair shop business model, but it is their business so they can run it how they want.

If you feel like adding an On/Off power switch between the battery pack and controller at some point in time then we have the parts available to accomplish that - just let me know and I direct you to the right switch and wiring directions.

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