Cart is driving very slow uphill

[poepjin]

I have a cart which I am not sure what model it is: It is one of those special carts built up by Elmco Inc. in Cooksville, Il. Below is a picture of the model/serial tag and of the cart. It runs on 48V.
The problem is it started to drive very slow uphill, forward as well as in reverse. The batteries are 3-1/2 years old. I put a individual load test on each of them and the performed ok. I also put Volt meter on each of them while driving up hill; all 6 batteries stayed well above 8V. Total voltage was above 48V.
I have the service book for this cart and did all the tests described and all the components seem to perform ok:
- It has a continuously variable Potentiometer. The test procedure in the book seems to be missing. I had problems with this in the past, as the cart would drive jerky but with full power. Then I lubricated that potentiometer and since then it worked well. But I did buy a replacement, just for the case that it would go bad completely. In the book it just describes its resistance: in the up position of the accelerator 0-300 ohms to appr. 5500 ohms with the pedal fully depressed. I measured and it is in that range. So it seems to work ok.
-I tested the solid state speed controller: I found a bad wire going from the solenoid to the controller, so I fixed it and was hoping this was the problem, but it didn't solve the issue. Controller input voltage and controller output voltage both tested ok.
-On-board computer:I performed a "reboot" and also a bypass as described in the book, no success.
What else can I check? Could it be also the brushes in the motor have to much build-up on the armature? That is what I found recently on a different el. motor. My guess was the controller is bad, but I just don't like to throw out that much money without being sure.
Thanks for any input.
pj

[Tom47]

Welcome to the forum.

I believe yours is a 1996 model from the serial number. I know nothing about that cart, but I think your suspicions of the motor brushes is accurate.

My cart did the same thing and after replacing nearly everything else, the motor was the issue. The brushes burned through the brush holder and it would run fine most of the time unless I hit a bump or tried to climb a hill.

It would be worth pulling the motor and checking it first.

[poepjin]

Originally Posted by Tom47

Welcome to the forum.

I believe yours is a 1996 model from the serial number. I know nothing about that cart, but I think your suspicions of the motor brushes is accurate.

My cart did the same thing and after replacing nearly everything else, the motor was the issue. The brushes burned through the brush holder and it would run fine most of the time unless I hit a bump or tried to climb a hill.

It would be worth pulling the motor and checking it first.

Thank you Tom47. I guess I will try that way; let's see what I'm gonna find.
Glad I found this forum.
pj

[poepjin]

Just dropped the motor: inside is some carbon dust, as expected. But the commutator looks surprisingly clean. No major carbon build-up like I expected. Measured for shorts but nothing. Brushes look clean with a lot of life left. Springs still strong. No signs of overheating. This motor is fine.

With good motor, strong batteries, working potentiometer...not much left to be bad. I come back to the controller: is there a way to test it other than what is described in the service manual?
Thanks
pj

[Tom47]

Well then....

That wire that was loose/ corroded on the solenoid may have caused the contacts to chatter, essentially burning them and preventing a good contact.

Try hooking a digital voltmeter to the motor field leads and drive it a bit. See if there are any fluctuations such as voltage loss or drop.

Then do the same with the meter connected to the armature leads.

Unless the controller got messed up due to the bad wire, I don't think that is the issue.

But I've been wrong so many times before, it has become a habit! Let's get someone smarter than I to assist you. That's about everybody here.

[poepjin]

Originally Posted by Tom47

Well then....

That wire that was loose/ corroded on the solenoid may have caused the contacts to chatter, essentially burning them and preventing a good contact.

Try hooking a digital voltmeter to the motor field leads and drive it a bit. See if there are any fluctuations such as voltage loss or drop.

Then do the same with the meter connected to the armature leads.

Unless the controller got messed up due to the bad wire, I don't think that is the issue.

But I've been wrong so many times before, it has become a habit! Let's get someone smarter than I to assist you. That's about everybody here.

Very honest!

[Reddawg454]

If you can go up a hill and your battery pack never goes below 48 volts then I want to know what kind of batteries you have because I'm gonna buy them next time. They must be some kind of super magical lead acid batteries that are 3 and a half years old.

[retiredtech]

Have you performed a voltage drop test on individual components? I found a large drop at the contractor on both of mine. Once I cleared that up they ran much better uphill.

[poepjin]

Originally Posted by Reddawg454

If you can go up a hill and your battery pack never goes below 48 volts then I want to know what kind of batteries you have because I'm gonna buy them next time. They must be some kind of super magical lead acid batteries that are 3 and a half years old.

They are made by NASA


No, they are simple Interstates. But I guess because something is wrong, the draw of current is small and the voltage doesn't drop as much. Once this is fixed I can make an accurate reading.

[poepjin]

Well, I think I nailed it down to the controller: I put the motor back together and installed it. I hooked my volt meter on the controller output and drove the cart around. In the beginning it was working better, than recently, but still my voltage was only around 24V-28V uphill. But then it reduced drastically to 14V-18V and the cart was snailing again uphill. That cannot be right.
I am very certain my controller is bad.
My question now is: Are there better or worse choices for a new controller? Should I just get one from Club Car or better from BGW or..???
Thanks
pj