[MattsAwesomeStuff]

the only certain way your Uncle will be able to drive his EV.

I have GE EV-1 controller from 1969. Works fine.

I don't think it even has electrolytic capacitors.

Semiconductors only being rated for 20 years.... come on man. 20 years ago was 1998. Yeah a few devices are going to go bad over time, but, it's not a plague (except for the capacitor plague, devices from early 2000s infamously fail due to attempted trade secret theft and counterfeit electrolyte failing).

It would certainly be easier to spend $100 on a little golf kart controller and be done with it, but, he's not condemned to failure just because he's using an old controller.

 

[MattsAwesomeStuff]

I could identify the components and test them individualy but using a transformer on a DC system to catch the current spike to the motor and use that to charge a capacitor so it could then be used to reverse bias the SCR to turn it back off,( and rated for 1000 amp) and the act of charging the capacitor reverse biases the SCR you used to connect the capacitor to the main SCR.... I knew what PWM was , but I never saw anything like that before.

That explanation succinctly summarizes what ten hours of reading and asking questions couldn't for me.

I finally get it now.

 

[MattsAwesomeStuff]

There are some very, very simple 36 and 48v golf cart controllers for $100-$300. My Curtis controller would do that.

Generally closer to the $100.

I'd go with one of those.

Literally just add the keyswitch, a potbox for speed, and strap the battery and the motor to it. Done and done.

Probably won't do highway speeds, but, neither will the old forklift controller.

 

[MattsAwesomeStuff]

It works!

If it's just a series DC motor (I think it is), you can switch the direction it rotates by just moving 2 motor wires, shouldn't have an impact otherwise.

The motor has 4 terminals. The start and end of 2 different coils. One coil is the rotating part of the motor, the other coil is the stationary part of the motor.

All you have to do, is pick ONE pair of those wires, and swap them. Not both pairs, just one pair. Doesn't matter which pair. Doesn't matter which is positive or negative. Whatever they are, just have them trade places.

You could do this at the motor, or, at the controller, shouldn't matter. But only swap cables that go to the motor. If there are other wires on the same terminal (like if you have a big stack of Negative wires), leave those alone. So it's easier to not screw it up by just changing them at the motor.