36V Marathon with controller, I need a little help

[TNTman]

Customer brought in a steel body EZGO Marathon, 36V cart he bought from his uncle. He also brought in new batteries he bought himself from Sam's Club. I expected to see resistor coils in this cart, but instead, there was a control box. I made custom 4 ga. cables for the batteries. At the customers request, I also replaced the solenoid, the microswitch back by the control box, and one of the switches on the FNR (would have replaced both, but did not have the double one, that also activates the backup alarm) and tested the other one to be sure it worked. After we did all this work, the cart would not move. Solenoid didn't even click. I found the string about how to test a motor by direct connecting a 12-24 volt power source, and we tested the motor, finding it worked. Then I found the right schematic on this forum, gave it to my mechanic, and he found that the wires leading to the control box were all out of place. He put the wires back like they should have been, and viola, the cart worked, and my mechanic drove it around the lot a few times. After all this was done, I made the cart street legal, installing headlights, tail lights, brake lights, and a slow moving vehicle sign. Called the customer to let him know it was ready, then moved the cart out front for pick up. When I put the cart in reverse, the tires even chirped as I backed out of the shop. I parked it out front, the customer came in and paid, then went out to put the cart on the trailer. Cart would barely move. I went and got a multimeter, tested the pack, and had 40Volts. Customer and I talked for a minute about what the problem could be, then he got on it again, and put it in reverse, pressed the accelerator, and it peeled out in the gravel. He put it in forward, it drove around fine for a minute or so, then it slowed down again. He barely got it on the trailer. He asked what the problem was, and I told him the most likely culprit was the control box. He had already been told it was hooked up wrong to begin with. He asked how much one was, and I told him I thought they were around $400. He is now mad at me, and wants me to give him all or part of his money back. I did all the work I was paid to do, and don't feel that I should be at fault, because the cart he bought from his uncle has a bad controller. At the same time, I feel sorry for him, that he has paid a total of around $1600 for a cart that does not work. Is there something besides the controller that could be the issue. Willing to listen to any ideas from the group.

Thanks

Robin

[JohnnieB]

If the controller works okay with the motor spinning in one direction, it will work just as well with the motor spinning in the other direction.

The differences between Forward and Reverse are both in the F&R switch assembly.

1. High current contacts.
2. Half speed microswitch. (one of the double microswitch pair)

It sounds like it is a high current issue. Perhaps the board holding the stationary contacts is warped from getting hot, or contact tension is out of adjustment, or just plain worn out.

Fix or replace the F/R switch's high current contacts and it should be good to go.

[Sir Nuke]

Robin, you said it "peeled out" in reverse then drove around your lot.....does it actually go faster in reverse then in forward?

[TNTman]

Thank you Johnnie B for your help. The cart does run fine in forward and reverse for a short period of time, then it will run slow. When it starts running slow in forward, when changed to reverse, it barely moves. Then you turn it off, leave it for a while, and it runs okay again, for a short period of time.

[TNTman]

Thank you as well Sir Nuke. So Johnnie I just checked my Nivel catalogue, and it sounds like you are suggesting replacing the FNR Contact board assembly (Part #776) and the FNR Cam (Part #425). Did I understand you right, cuz I will order them right away, if this is the case.

Thanks again

Robin

[JohnnieB]

I'm saying the F/R switch's high current contacts are the most likely cause of the symptoms you've stated.

Chances are that replacing both the cam and contact board would fix the cart, but I cannot be 100% sure without taking some voltage measurement to see if there is a voltage drop across the contacts when there shouldn't be.

[TNTman]

Ordered the whole assembly instead of the individual parts. About $7 less than ordering all the parts individually and then having to assemble it, and includes some of the wiring, so I won't have to use the old wires for the backup alarm.

Appreciate you guys expertise, and I really hope this will correct my customers issues.

Robin

[TNTman]

Okay, got the new FNR assembly and installed it. Cart was working fine, customer came and got it, drove it around for about a week. Then he went to go up a hill, and it started creeping again. He limped it home, and charged it overnight. Next day, it will still only creep around at a very slow speed. He says it is fully charged. I will have him bring it in again next week, but I have no idea where to look next. Any other ideas out there. As always, thanks for your help.

Robin