91 EZGO Marathon very weak

cbordea

we use our cart often but not for long periods of time.
I usually plug it in every night.
Several weeks ago, I pulled the cart into the garage and plugged it into the charger. The charger buzzed kind of loud and I saw crickets running for their lives and I heard a pop. I figured that a cricket got in there somehow and got fried. The charger seemed to hum like usual.

I use the cart for the next few days and plug the cart in at night, charger still humming like usual but I began to notice the charger never jumped up to the 30amp cycle, it just stayed at 10amps.
After a couple of days I notice my cart is getting weaker.
I look at the charger and notice the fuse on the front is blown.

I ordered a fuse kit and a diode/heat sink for the charger.
I replaced those and charged each battery individually while waiting for the parts to arrive. Most of the batteries were down in the 35% area.

I replaced the fuses and the diode/sink.
I hooked up the charger and it immediately jumped back to 30amp but quickly settled down to 10amp. I knew the batteries were charged so that made sense to me.
I unplugged the charger and took the cart for a spin.
The cart would go but wasn't quite itself.
I checked all my connections and noticed one of the wires from the controller to the I think negative post was skinned pretty good. I replaced that wire and noticed the charger would not jump back up to 30amps, only stay at 10amps. Upon further investigation I notice that the charger amp meter is stuck at 10amps even when the charger is off. I don't think the charger is charging.

I recharge each battery individually again to see if that helps.
I get the same results, the cart is weaker than ever.
I check all connections/wires etc. The only thing I can see is one of the terminals on the motor has a slight amount of wiggle. I noticed that wire was loose a good while back so I tightened it up and the cart ran fine then even with it having a slight wiggle.

What else should I check?

I noticed on the controller there is a diode/resistor looking thing that runs between two connections that is broken. If I remember, that diode was broken when I installed the new high torque motor ( a year or so ago) and everything seemed fine. I'll attach a pic ( I borrowed from the web) of where that diode was below. Somehow in the process my multi-meter died so I need to get a replacement before I get deep into troubleshooting.

My thoughts are something is wrong with the controller which is limiting power and not allowing the charger to kick in but I don't really know how to verify that. Also this being a 91 you begin to wonder at what point do you stop the bleeding.

BGW

__________________
This advertising will not be shown in this way to registered members.
Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum

cbordea

BTW, the batteries were bought new in late 2011 and are all topped off with distilled water, all connections are clean. None of them even feel warm after a little drive.

yurtle

Have you tried tapping the front of the ammeter with your finger? It "might" unstick it.

cbordea

I'm pretty sure I tapped it, will try again.
I can tell the difference in sound though when the charger is putting out 30 amps vs 10. I don't think it is charging at all. I'm thinking whatever is making the cart weak, is not letting the charger come on and charge. Kind of like when the batteries are too weak or out of balance the charger won't charge.

yurtle

Does the charger automatically turn off? If so, measure the voltage of the pack while charging and just after it shuts off.

yurtle

Also may be worth opening it up, to see if fried bug guts need to be cleaned off the circuit board(s). Be very careful if you aren't familiar with electrical repair, as the capacitor holds a lethal charge, and should be properly discharged.

yurtle

Assuming the problem started with the cricket infestation, you might just start by blowing it out with a shop-vac or leaf blower.

cbordea

I blew the charger out with my air compressor.
I'm thinking the cricket thing was just a coincidence.
I would expect though since I have charged each battery individually to 100% then the cart should run normally.
I think once I figure out the weak cart, the charger might work again.
The charger does not turn off now.

I ordered a new multi-meter, it should be here Saturday then I can check the voltage of the pack.

I would expect though since I have charged each battery individually to 100% then the cart should run normally.

cbordea

ok, I verified the charger does turn off overnight.
I'm going to try cleaning the cables again. Some of them I put a pretty good coat of grease on to keep them clean. I haven't had any problems with them in the past but I'll see if that helps at all.

Is there a way I can verify my controller is ok?

JohnnieB

Excessive resistance in the high current loop, will make a cart sluggish and excessive resistance in the charging loop, can fool an automatic charger into shutting off prematurely, under charging the battery pack.

The batteries and their interconnecting cables/connections are part of both circuits, so one problem could be causing both charging and performance issues, or they may be separate issues.

When your DVM arrives, measure the pack voltage about 12 hours after the charger shuts off automatically. It should be 38.2V for a fully charged 36V battery pack.

-------
To check if the charger is sensing the true pack voltage, measure the voltage on the red and black wires going into the control board while the charger is putting out several amps and then measure the pack voltage while charger is still putting out the same number of amps. The two voltages should be identical.

---------
To check the controller, measure the the pack voltage and the voltage between the B- and M- terminals on the controller when the pedal is pushed just far enough for the solenoid to click. Both voltages should be identical.

Let us know what you find so far and we'll proceed from there.

BTW: What is the Make/Model of the charger you are using?