My 2001 EZGO Moves Like a Snail With Fully Charged Batteries

[Trevor Howard]

I've read many of the posts regarding this issue. My 2001 EZGO moves like a snail with fully charged batteries. I'm thinking that my problem is with the speed controller. Is there a way to check the controller to determine if this is the problem. There seems to be a couple of other components that would mimic the issue as well. What else can I check to possibly isolate the problem? The batteries are in good shape so I've eliminated them as the culprit. One other issue that has been going on for several years is when I switch from reverse to forward the cart will start and then stop momentarily. After releasing and depressing the accelerator pedal the cart performed just fine. This only happens occasionally. One last thing. Would a faulty speed controller cause my Powerwise charger not to work? The unit was working fine and out of the blue it quit. The charger unit has been rebuilt so I don't feel there is a problem with it. Thanks in advance for anyone who can give a little direction.

 

[HotRodCarts]

Is your EZGO a Series or PDS system? The controller would have no effect on the battery charger. Welcome to the forum.

 

[Trevor Howard]

Thanks for the timely response HRC. Series or PDS? Haven't a clue. How do you determine which one it is?

 

[HotRodCarts]

If the forward and reverse switch is on the dash and it has a run tow switch under the seat it's a PDS. Forward and reverse switch by your right leg is a series system.

 

[Trevor Howard]

Thanks HRC. Based on your info it is definitely a PDS. Now I know what that means...!!!

 

[HotRodCarts]

No problem. When you say the cart moves like a snail how fast is it actually going? Have you hooked a volt meter to the battery pack to see how low the voltage drops when the golf cart is moving? If not I'd start with the voltage test.

 

[Trevor Howard]

Ok, I just did the voltage test. Battery pack started out at 36.1 volts when I moved the cart (in reverse) it dropped to 27.7 volts forward, it dropped to 28.9 volts. Now it barely moves in either direction.

 

[HotRodCarts]

You definitely have a battery problem. Have you checked the batteries to see if they need water? I'd check and if the plates are exposed in the batteries add enough distilled water to just cover them. Then charge the batteries until the charger shuts off and fill them to the proper level after they're charged and charge them again Then do the voltage test again while driving the golf cart. You can also test each individual battery the same way just hook your meter to one battery at a time and see how low the voltage drops. Let us know what happens and we'll go from there.

 

[Trevor Howard]

Ok, I'll do that first thing tomorrow. One thing I failed to remember was if you have one bad boy in the bunch it makes the other five look bad too! In reality, I hope it is just a battery problem. That's an easy fix in time, effort and $$$. I do appreciate your input. It's reduced the aggravation to almost nothing. You guys are super and above all patient. Thanks.

 

[Patrick L]

Ok, now I have a related question. How much voltage drop under full throttle is acceptable/normal ?

 

[HotRodCarts]

On a 36 volt golf cart the battery pack voltage shouldn't drop much less than 36 volts and the voltage should slowly increase after the cart reaches top speed.

 

[Patrick L]

OK thanks. You would think I would've checked this by now, but,,,,,
I don't want to hijack this thread, but, I'll check it at the batteries [ all and each] and then at the controller leads.
The cart doesn't run as fast and doesn't seem to have the power it had after all the work I did. I'm thinking there is now a problem with the controller or the new brushes.

 

[Trevor Howard]

Ok guys.... I checked all the batteries and all the plates were covered. Charged the batteries. Topped off each cell, as needed and then charged them again. Once that was completed I checked the overall voltage and it read 37v. Then I checked the voltage drop. The voltage dropped to 36.5v when moving. Then I checked each individual battery. All had a reading of 6.1v. When moving they dropped to 5.8v(+/- .1). Seems that the issue may be solved. Now, I'm no expert on electrical issues by any means, however, my theory on the problem dealt with my charger. You can correct me if I'm wrong. I rebuilt my charger several weeks ago and seemed to work as expected. One component I did not change was the capacitor. I think that even though the charger was working, it was not fully charging the gang before cutting off. When the charger finally quit altogether I went back into the unit and found that the capacitor was faulty. I replaced the capacitor and the unit appears to now be working as expected. Could a faulty capacitor been the culprit by not allowing the batteries to get full charge before cutting off? I have no idea what role the capacitor plays in the function of the charger. I had noticed that after charging and running the cart for a little while(minutes), the gauge indicated that the batteries were half full. It was a mystery to me why they were discharging so quickly. It appears that issue may be solved. One last question. Battery Life Saver(BLS); is this component worth the investment(they aren't exactly cheap!)?

 

[Patrick L]

I hope your problem fixed. The battery voltage still seems a bit low to me, but as long the cart runs 'more better' then it seems like its fixed.
As for the de-sulfator, some swear by them and others swear at them. I installed one and don't yet have an opinion.

When you checked the capacitor, what were the numbers ?

 

[HotRodCarts]

I agree with Patrick L 6.1 volts on each battery is low. A fully charged 6 volt golf cart battery should have about 6.4 volts. It is possible the voltage may go up a little on your batteries after a few charge cycles.

 

[Trevor Howard]

Patrick...when I checked the capacitor I got no reading at all. I understood that it should read 1.5 to 1.7 ohms. So I replaced it.
HRC: I'm still at a loss as to what the capacitor does as far as the charging function is concerned. Can you enlighten me?

 

[HotRodCarts]

A capacitor is a passive two-terminal electrical component used to store energy electrostatically in an electric field. Unlike a resistor, a capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates. Really the only thing I know about capacitors is they need to be discharged before messing with them. They can store enough energy to kill you is not properly discharged. I'm sure someone else on the forum can give you better information on how they work in a battery charger.

 

[Patrick L]

What's the use of the capacitor of a battery charger?

A very common, efficient and reliable type of battery used for lead acid batteries is the ferroresonant charger. The secondary winding has a separate winding that connects to an AC capacitor, usually physically large and mounted separately from the controls and diodes. There will also be a gap between the primary and secondary windings filled with core material.

As the battery charges and the battery voltage increases so does the voltage to the capacitor. A the capacitor voltage increases the winding forces the AC current through the power windings to go down.

That is important because once a battery on charge reaches the gassing voltage which is 2.38VDC per cell the current has to be about 4 to 5 amps per 100AH of battery capacity. Before gassing 15 to 17 volts per cell is OK.

If the current is not reduced the battery will use water (gases - H2 and O) and overheat causing permanent damage.

The charge controller turns on the charger if the battery has the correct number of cells, senses the 80% (gassing) voltage, waits three hours and turns off the charger. Simple, reliable and low cost. Often there are a few other handy features built into the control.

Simpler than SCRs, IGBTs, HF etc. Usually cheaper too.

I often worked on 30 or 40 year old ferro chargers. Failure of the ferro capacitor was uncommon. Usually it was the control board that needed replacement.

Most chargers don’t need a capacitor across the output because the battery is a capacitor.

Ferroresonance in chargers is a very interesting subject. Check it out yourself.