New electric motor-axle turns when put in gear

[chmguns]

Original motor got burned up when my wife got stuck in the mud. No biggie- I had expected the original '84 motor would not last when I upgraded to 48 volts & SS controller. Replaced motor and also replaced F&R switch since I had not been happy w/ the first one I bought. Hooked it all up and turned on key, put it in gear(on stands) and the axle immediately started to turn at about quarter speed. Tried reverse and same thing. Depressing the pedal whilst in gear caused the motor to stop. Started tracking voltage and found resister was too hot to touch. Getting voltage on both sides so I figured solenoid is my problem. Even though it is 48v/200amp constant. I pulled it but when I tried it out of circuit it works perfectly. So is my Alltrax controller bad? At a loss to figure out what else. It is an older nonprogramable (3 screw pots to set) 0-5k conversion kit from ScottyB that has been flawless til now.

[bronsonj]

Could be the throttle? You said she was stuck in the mud, maybe there's a little water in the throttle box?

[chmguns]

IDK- don't see how the resistor would get that hot if its just the throttle stuck. I can't see finding voltage on both sides of the solenoid when there should not be any and how it slows and stops when the pedal is depressed. I blew compressed air though the housing but I haven't taken the assembly apart. The ohm check on the pot is OK. Wondered if the motor might be miswired, I have retraced the hookups and thats all good so it seems its inside something

[scottyb]

Thanks for moving this to the forum
The resistor get hot when the solenoid fails to close and the controller ask the motor to go. The poor precharge resistor become the only current path between the motor and the battery pack.

1. is the solenoid clicking when you try to go?
2. per the tests I email you did you remove the resistor and see if the solenoid was in fact closing when it clicked?
3. The F&R could be compromised also .....?

[JohnnieB]

If the conversion kit KSI wiring is the same as the stock Marathon controller cart, the controller powers up when the key is on and a direction is selected, so the issue might be as simple as the potbox needs to be adjusted for the pedal up position.

If the ohms between the black and white wires are more than about 300Ω (or whatever the pedal up spec is) the controller will increase the duty cycle of its PWM output to the motor to above 0% and without the pedal being pushed, the solenoid contacts will be open and the pre-charge resistor will get hot.

[chmguns]

It appears we have a winner!!!
I checked the leads to the throttle 0-5k pot and then unplugged it and tried again with just the pot in circuit and got the same result. Right at 9k with the pedal relaxed the falling to 0 with a little motion then grading up to 4,7k at full depression. So I guess I need a new pot

[JohnnieB]

Originally Posted by chmguns

It appears we have a winner!!!
I checked the leads to the throttle 0-5k pot and then unplugged it and tried again with just the pot in circuit and got the same result. Right at 9k with the pedal relaxed the falling to 0 with a little motion then grading up to 4,7k at full depression. So I guess I need a new pot

Might just need some adjustment. IE: Set to mechanical Zero.

I've got some info on adjusting the potbox in my stash, but can't find it at the moment. I'll do some searching and post it when I find it.


In the Marathon controller carts, the length of the rod from the pedal is adjustable as well as the rotation angle and span of the potentiometer.

[JohnnieB]

Found them.