2006 36v EZGO charging issue

[vandv]

Wow! I like these forums and everyone's sense of humor. Motorcycle guy here (HD of course) and recently found a new toy to spend money on. 2006 36v EZGO PDS, all original. The batteries were original so I changed them out for all new Trojan T-605's because it died on me after a short trip on the beach where the cart did real well for about 2 or 3 hundred yards in the sand. Let it set for a while and made it back to the camper. Came home put them on the charger over night thinking it was that easy. Took the grandkids out in the grass and it stopped again. Made it home once again put it on the charger and registered here on the forums and started reading. Went out to check and the charger had stopped as if it were done. With a digital meter read 35v across the pack and 5.8v on each battery. Water levels exactly 1/2" about the plates. From what I've read that is only 40% charged. All wires are in perfect condition (I'm an industrial controls manager). I did go through some of the basic test and everything is consistent with the original readings mentioned above. My diagnoses is the charger is bad and needs a 20x370 run cap. I have 20x440 on the shelf in my shop. Any further though is greatly appreciated.
V

[JohnnieB]

The 20µf/440VAC motor-run capacitor will sub for the 20µf/370VAC original, but if the charger is shutting off prematurely, that capacitor isn't the problem, or at least not the only problem.

There is a control board that is supposed to turn the charger on when it senses a battery voltage of about 30V or more and then shut it off when the on-charge voltage reaches about 45V, or after about 16 hours if the on-charge voltage fails to reach about 45V. Basically, the control board is a semi-smart On/Off switch. The charger consists of the Ferroresonant Transformer, 20µf capacitor and Diodes.

When the charger first turns on, the ammeter ought to climb into the upper end of the scale (about 20A) and stay there until the on-charge voltage climbs above 40V. Then it will taper off down to about 5A until the battery pack's on-charge voltage reaches about 45V. If the ammeter doesn't go to something upwards of 20A initially, then the capacitor, diodes or transformer may be bad.

What is the make and model of your charger?

[vandv]

From the s# it looks like a 2004, Power wise Industrial charger M# 28115 G04.
Initially, the charger starts off at 15amps and after a little while drops to "0" and turns off. It's 104deg here is Houston so I don't hang out in the garage long this time of year to monitor it.
I just plugged it in again and it registers "0" even after I hear the relay close. The volts are still 35v and 5.8ea. Shortly thereafter, it turns off.
V

[JohnnieB]

Find a shady spot with a breeze to move the cart and charger to while troubleshooting.

The charger (service manual attached) is acting like the batteries are charged, but the voltage readings and the way the cart is acting indicate they aren't charged.

The first thing I'd do is verify the voltmeter is reading correctly.
Then I'd bypass the relay in the charger so it stays on all the time it's plugged into AC power and monitor the voltage at the main positive and negative terminals of the battery pack while the charger is connected to cart.

Dirty contacts in the charger plug and cart's charge receptacle, and/or corroded connections in the charging loop, will cause the charging circuit to see a higher voltage than what is being applied to the batteries.

[vandv]

Well, I replaced the cap, diodes and resistor and it didn't work. I just re-read the last reply and noticed it said, "transformer". I seem to do that sometimes when I THINK I know what I'm talking about. How would I go about testing the transformer? I know I have the 120v I'm assuming like all transformers I would test the load side of it. What voltage should I see and where do I test at? After this I'm taking it to the golf cart repair place.
Thank you any help,
V

[timmyjane]

Originally Posted by JohnnieB

The 20µf/440VAC motor-run capacitor will sub for the 20µf/370VAC original, but if the charger is shutting off prematurely, that capacitor isn't the problem, or at least not the only problem.
?

My charger was only running for about 30 mins or so and cutting off. I didn't do any testing but a visual inspection said the capacitor looked bad. It was all rusted and the wires were barely hanging on. I replaced it with an equivalent and it got my charger going again. It shuts off at 44-46v now. Maybe I got lucky but I think that the cap was the only problem.

[cgtech]

Well, you should be able to clip your meter leads to the outer 2 diode terminals and read about 90v when charger is activated(with meter set to 200v AC). Be careful, 90v will definitely bite you!

[JohnnieB]

Originally Posted by vandv

Well, I replaced the cap, diodes and resistor and it didn't work. I just re-read the last reply and noticed it said, "transformer". I seem to do that sometimes when I THINK I know what I'm talking about. How would I go about testing the transformer? I know I have the 120v I'm assuming like all transformers I would test the load side of it. What voltage should I see and where do I test at? After this I'm taking it to the golf cart repair place.
Thank you any help,
V

The attached tests check both capacitor and transformer.

Like, CG said, be careful, the voltages involved can bite.

[vandv]

CG wouldn't that be DC voltage on the meter?

[JohnnieB]

Originally Posted by vandv

CG wouldn't that be DC voltage on the meter?

You measure with the diodes disconnected, so it is VAC.
90VAC with capacitor connected, 60VAVC without capacitor.