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Installing SPD36500R controller on minimoto

I am installing a SPD36500R controller on my son's Minimoto Go Kart. The wiring seems straightforward but I am not getting any power through the key switch relay wiring on the controller. I can hear the reverse relay operating but not the key switch. There is the indicator wires, which right now I do not have hooked up to anything. I also do not have the brake light wires hooked up. The on/off toggle on the kart is operational; I've tested it with my multimeter. Coming out of the controller - to the on/off switch is about 28v. This is a 36v controller and I'm wondering if this is normal. I have charged the batteries through the controller and this is functioning fine. What am I doing wrong with the power switch? The controller is not delivering any power to the motor. Is the on/off switch supposed to be connected to the indicator wires? Thanks in advance for any help with this.

On the SPD-36500R controller I remember that there is only one relay for the reversing function, and no relay for the power switch function, so there would be no clicking sound when the key switch was turned on or off.


If you can hear the reverse relay clicking when the reverse switch is engaged that indicates that the power switch is connected correctly and working, as the reverse relay will not click when the power switch is off or not wired correctly.


The indicator wire connections are optional and do not need to be connected to anything in order for the controller to operate. The on/off switch should definitely not be connected to the indicator wires otherwise the controller might be damaged, as the indicator wires are designed for connecting to light bulbs only.


Since the motor is not operating here are the steps that we recommend taking to troubleshoot the problem.


  1. Disconnect the brake switch from the controller and see if the motor runs then. If the motor runs with brake switch disconnected then the brake switch is faulty and needs to be replaced or left disconnected from the controller.
  2. Test the Voltage of the battery pack with the power switch on and throttle fully engaged. The battery pack Voltage must not be under 32 Volts during this test, as the controller shuts off the motor at around 31 Volts. A good 36 Volt lead acid battery pack should be at around 41 Volts when fully charged, and should not drop less than 1-2 Volts during the test. If the battery pack drops to 32 Volts or less during this test then it is old or worn out and will need to be replaced.
  3. Test the throttle to make sure it is receiving output Voltage from the controller, and providing a Voltage signal to the controller. Throttle Testing Guide
  4. Test the motor by connecting it directly to a battery to make sure that it is working.


Hopefully the problem will be discovered during these tests. If not then please let us know so we can offer further assistance.


Please let us know how it goes.

Thanks for the quick reply. Here is where I'm at with this right now. I've tested the brake switch and it is operational. I've tested the power switch and it is operational. The reverse relay works whether the power switch is on or off. In fact, it will work with everything disconnected and only the battery pack connected (and the reversing switch). As soon as power is supplied to the controller, the reverse switch will operate. There is no power coming out of the controller to the hall effect throttle. I have tested the output voltage from the battery pack and it is 40 volts. I also hooked the power supply directly to the motor and it is operational. When I have the charger hooked up to the system, I will get voltage out of the controller for the throttle. When I disconnect the charger, the controller no longer delivers power to the throttle. I still have not figured out what the issue is. It is either something simple I'm overlooking or by chance I've received a faulty controller. Thanks for your help.
Usually when an electric go kart runs with the battery charger plugged in, but won't run when it is not, that is an indication of bad batteries.

Have you had a chance to test the battery pack Voltage with the power on and throttle fully pressed?
I understand. However, the batteries are new (or nearly new- three months) and the go kart will not run plugged into the charger. I can only get a voltage reading out of the controller with the charger plugged in. I cannot get a voltage reading with the throttle fully depressed because there is no power going to the throttle and no motor draw to test. The motor will not run through the controller. I will go through the motions again this weekend and see if I can narrow down the problem.
I read your previous reply again and now understand that when the charger is plugged in the throttle then receives Voltage from the controller, and when the charger is unplugged the throttle does not receive Voltage from the controller. That could be caused by the battery pack Voltage dropping when the power switch is on causing the DC-DC converter inside of the controller to not output power to the throttle, then when the charger is plugged in the controller then receives enough Voltage to function and send power to the throttle. These is all just speculation though - it is difficult to diagnose vehicle electrical problems when the vehicle is sitting right in front of you and you can touch and see it, and much more difficult when all you have are words to diagnose it with.

We have seen a few brand new defective batteries before so even though the batteries are new I would not rule them out as not being the problem until they have been load tested.

The reverse relay should only engage when the power switch is on, otherwise it could drain the battery pack when the power switch is off. I am not sure if there is a problem with the wiring between the controller and switches, or a problem with the controller though. You might want to try running new wires from the reverse and power switches to the controller to make sure that the old wiring harness is not causing the problem.


Our technician bench tests all of our SPD-36500R controllers before they are shipped out to make sure that they work, so the controller that you have is supposed to be working. However if you feel that it is not working then we would be glad to test the controller again to confirm if it works or not, and replace it if it is defective.


We will work with you until this gets resolved. Please let us know how it goes.

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