Blocking dc voltage

Components & Accessories Power
1

A little background on my project:

home made electric go kart

Motor: 48v 1000w brushed

Speed controller: 48v 1000w (x2)

Battery: homemade Lypo 12s 18A

I’m wiring my sons go kart up and have run into an issue. His go kart has no space for a mechanical brake, so I decided I would use the motor as a brake by switching the polarity of the battery. Since I have 2 of the same speed controllers I figured I would use one controller to go forward and the other for reverse/brake. I have 2 throttle levers attached to the steering wheel that are a lot like paddle shifters on a car. They are wired through the frame of the kart and are connected to their own speed controller. The positive and negative power wires are connected in parallel and connect to the battery.

And this brings me to why I’m writing this. Because I have 2 speed controllers I also have 2 outputs that are going to be connected together going into one input (motor). If I use the accelerator throttle the +48 volts will be going into the motor like it should but it will also be traveling into the reverse/brake speed controller and most likely ruining that speed controller and vise versa the -48v will travel into the accelerator speed controller.

Is there a way to completely block the voltage that would be going into the output speed controller that isn’t being used ?

2

Hello, and thanks for posting!

Unfortunately there’s not a great way to do this at the power levels your running your motor.

Connecting two motor controllers to the same motor risks damaging the unused controller unless it’s specifically setup to be connected to a second controller. Reversing the battery leads could damage both controllers.

If you had a large DPDT relay, you could wire that to a speed controller and activate the relay to either disconnect the motor from the driver and then short out the motor leads, or reverse the polarity on the motor leads. Either of those might damage the controller as well though since controllers are not generally made to see the motor disappear or suddenly change polarity.

The safest and most reliable method would be to find a way to install a mechanical brake since that should always work even if the speed controller fails while you’re driving, OR get a speed controller that has a brake function on it. (although if the controller fails, you have NO brakes.)