91 EZGo won't go.

[cbordea]

I recently bought a 91 EZGo for $300. The previous owner said it is a Marathon but the label says Textron.

The previous owner said it was working fine in August but his wife hooked up the charger backwards and fried one of the batteries. I can see the battery is bad, the terminal post is melted and the case is cracked.

He told me that I should be able to put one battery in and be good to go. After a little research here, I see the batteries are 8 years old. I tried charging some of them individually just for kicks but getting mixed results.
I know I need 6 new batteries.

I'm completely new to carts but have read through many of the stickies the past few days and am generally a good troubleshooter and I have a meter.

The cart has some rust in the battery tray but I can build a new one if I can't salvage this one. I don't want to buy 6 new batteries and find out there are more expensive problems lurking. I would search but I don't even know terminology well enough to search.

Looking over the diagrams, below is the closest one to my cart.



I spoke to a cart dealer who said I could basically use jumper cables from a neighbor's cart to see if mine would work. It got me to thinking, I should be able to use 3 12V batteries to see if it works. I wired my 3 12V Marine batteries in series and hooked everything up. My onboard gauge is reading at Full.

There are two heavy wires that run from the pos of batt one and the neg of battery 6(or 3 in my case). They run to a module under the seat (where A2, B+ and B- are).
The "gas" pedal has a rod that connects there as well.
When I turn the key I hear a noise in that module.
What is that module called?

When I press the pedal nothing happens, no noises or anything.
I am going to go back and clean all connections.
What else can I check.

I know 3 12V batts are not enough to run the cart but I would expect they would be enough to make it want to move. Am I off base here? I would expect it to work but not take long to run them down.

I keep my try to keep my marine batteries fully charged at all times. Even in the winter I'll hook them up to the charger every few weeks to keep them maintained.

Any ideas? I might try hooking the batteries up to my charger and try topping them off.

On my list right now...
top of 12V batts
clean all connections.
Anything else?

Normally I would just buy the batteries and begin re-placing parts but if I buy the batts, I'll have $800+ in it and from time to time around here I can find good running carts with good batteries in better shape for not much more than that.

[Andy4639]

The module you speak of does it look like this?



This is normally refered to as a Pot box ,short for potentiometer.
This is what signals the controller to go. It works off OHM'S.
There should be a micro switch also on it that turns the controller on and off.When you turn the key on the micro shouldn't come on until the gas pedal is mashed enough to engage it.
Then the solenoid and controller come on and the cart should move with a little more pedal.3-12 volts will run the cart fine just want last long.

[cbordea]

Thanks Andy, I haven't pulled that cover off yet but I think we are talking about the same part.
I'll take the cover off this afternoon and take a look.
I'll also clean all the contacts and top off the 3 batteries.

[JohnnieB]

The module with A2, B+ and B- (and M-) cables attached to it is a Solid Sate Speed Controller and is typically just called a controller.
The module the pedal linkage goes to is called a Pot Box.

The Controller is basically a light dimmer on steroids and the potentiometer in the Pot Box tells it how much current the motor is allowed to draw.

I'm not sure what you are hearing when you turn on the key, but with the key on, and F/R switch in either F or R, you should hear the solenoid click (or clunk) when you push the pedal.

You might want to jack up the rear far enough to lift the tires off the ground so the cart doesn't take off unexpectedly while you're working on it.

36V is 36V. so your three 12V batteries will be fine for testing and troubleshooting. They probably won't hold a charge very long trying to drive cart with them.

The first thing is getting the solenoid to click when it is supposed to.
Then troubleshoot the High Current circuit.

Here is a schematic of a Controller cart with a Pot Box.

It isn't marked, but MS-3 is controlled by the pedal. It is the last link in the series of switches that need to be closed to activate the solenoid.

[cbordea]

ok, I took a break from work (I work from home) went out and checked the connections and topped off the batteries and it will work kind of.
It seems sometime I have to press the brake all the way down and lock it and then press the gas pedal to get it to go. It will keep going fine until I press the brake. I'll press the brake, lock it, press the gas and then it will go again.

It was pretty consistent until the batteries got weak, then it just stopped.
I'm going to go get 6 new batteries. I've seen enough to think it is worth the investment.

[ab46501]

FYI the 91 model is called a Marathon. If your 3 12v batteries had a good charge it should turn the motor no problem. It is possible if the previous owner hooked the charger backwards it may have fried or damaged something else.

At the very least I would consider running all new 4ga wiring with the new batteries.

Also you might want to think about upgrading to 48v depending on what you are going to use the cart for. Now would be the time to do it since you have to buy batteries anyway and possibly replace other parts. I have a 91 Marathon as well and if I had it to do over again I would go 48v from the start.

Read up on this website it has loads of info and can give you a good idea of what to do and what options are out there.

[Andy4639]

I can't see how the brake has anything to do with it. It's not tied to the electric system at all. The micro switch on the pot has to activate before the cart will move. The wiring diagram is the right one for your model. You need a meter to check voltage. Make sure there is nothing grounded to the frame nowhere.

[cbordea]

I got my new batteries and charged them individually this afternoon.
I'm unsure if it is my charger or what but it seems they would charge to about 70 percent and then kind of plateau. Once they all got to about 70 percent I hooked everything up and the cart works.
I think my issue with the break is coincidence. It seems when I change directions or brake I have to press the gas pedal at least 2 times to get it to go. The first time I hear nothing and then the 2nd or 3rd time I hear the signal and it goes.

I ran it a few minutes and then hooked it up to the 36 v charger to charge overnight.
I'll read over the break in procedure again to try to make sure we do it right. The previous owner had the meter hard wired to the battery, I'll move it to work off of the switch instead and may upgrade to one of ScottyB's later.

On upgrading to the 48V model, I can see the need. I know the batteries aren't fully charged or broke in yet but going up any kind of hill at all this thing seems weak. I think it will serve our purpose though for the kids to beat around the house. I can see us using this one a few years then upgrading to something else.

[JohnnieB]

Patience is a virtue.
Especially when it comes to charging Golf Cart batteries.

Hopefully, your new batteries will get fully charged before they are used much more.
The first charge, collectively or individually, will probably take 12 hours or more.
The back-up timer on a Automatic shut-off type 36V charger might terminate the charge before the battery pack is fully charged, so restart it.
If they were fully charged, the charger will shut off in a half hour or less, if they weren't, it will continue until they are.

Just curious, but how did you determine the batteries reached a plateau at about 70% while charging?

Having to push the pedal two or three times to get it started sounds like you might have something loose or some dirty contacts in the solenoid activation circuit.
With the Key Switch turned ON and the F/R control in F or R, the solenoid should close every time the pedal is pushed.

[Andy4639]

Check the micro switch arm on the pot itself. Make sure the arm is straight and is making good contact with the throttle linkage. I have seen them bent and causing this condition.