EZ Go Total Charge timer won't shut off

wjslam

New to forum (and golf carts). My charger is an LR-69689. Battery bank is at 37-38 volts. I plug charger into AC outlet, set timer to 'off', plug in DC connector and there is no 'relay click'. So I turn the timer knob clockwise to 'start', timer starts ticking, amp meter deflects to 25 amps and charging begins. So far, so good. After 10-15 minutes, amps have dropped to near zero (not zero), battery pack is 46+ volts and timer continues to run. Timer will not shut off, and charger continues to charge at perhaps 1-2 amps until timer knob returns to near the off position (11 hours of charge time). I am suspecting from my research that the control board is bad. Looking for other suggestions as to diagnostics. As for now, I charge batteries and keep an eye on time, then disconnect the charger and connect a 36v maintainer to protect the battery bank. Any help is much appreciated!

BGW

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JohnnieB

The relay must be clicking (contacts closing) or there wouldn't be a 25A output. Probably just a very quiet relay.

Typical shutoff is when the On-Charge voltage climbs to 45V +/-1V, so it ought to have cut off if the voltage climbed above 46V. (Bad control board)

Amps dropping down to near zero in about 15 minutes may or may not be okay. If the batteries are very near being fully charged, the on charge voltage will climb past the point where amps start to decrease fairly rapidly. And there are some battery issues that will do about the same.

What is the battery pack voltage about 12 hours after charger is turned off?
What is make/model of batteries
How old are they?

Lochlin

It seems like you have an old-school charger that uses a timer to control the charge more than voltage. I have a couple of those still.

Indeed, your timer is what turns things on and off with your charger. The voltage is secondary. There will always be some voltage so long as the timer is still on. Low voltage going to back to your battery pack for several hours is fine, though. I think you are good.

Should you ever get a modern charger that uses voltage, rather than time, to determine charge rates don't EVER get rid of that old one! Though those old ones don't charge as effectively as the new ones they are priceless for bringing overly discharged battery packs back online.

Just a month ago I had a fellow camper borrow one of my old timer chargers from me to rescue his pack. His batteries were too discharged for his smart charger to kick on. My old charger doesn't care and had his pack back up in no time.

wjslam

JohnnyB, battery pack is mixed bag:
1 Trojan t-125 (age unknown b/c date code on terminal is illegible)
3 Trojan t-105 (sep 2017)
2 Duracel (East Penn) GC125 (Jan 2019)
Open circuit volts at 12 hrs+ following charge is 6.304-6.413 (lowest to highest)

My understanding is that both timer and charger should shut off at 46+ volts. Where timer stopped indicates time it took to charge. Is that correct for this model? If so, I'm going to order a control board.

Lochlin, I agree that this charger is a keeper.

PS Once i'm inside to replace the board, any other preventive maintenance items to test/replace?

Thanks much for the help to both of you!

JohnnieB

Ouch! Mixed bag of brands and AH capacities and ages. A triple whammie.

1 Trojan t-125 = 240AH -- 100% SoC = 6.37V
3 Trojan t-105 = 225AH -- 100% SoC = 6.37V
2 Duracell (East Penn) GC125 = 235AH -- 100% SoC = 6.33V

Some of the batteries are being over charged while others are being undercharged, but I'm not sure that is what is causing the charger's abnormal operation.

The Total Charge Model 20484 (LR 69689 is a Canadian Standards Association listing, just like the 20L4 is a UL listing) is a transitional generation of Ferroresonant Transformer type chargers. The preceding generation charger was turned off solely by an electromechanical timer, the proceeding generation was turned off by a voltage comparator on a "Control" board with an electronic backup (safety) timer.

The TC-20484 is turned off by a voltage comparator on a PCB board, but uses an electromechanical timer for the backup timer. The timer's pointer was also used to show elapsed time of charge cycle.

The control board and timer have nothing to do with the charging volts and amps. All they do is connect and disconnect the AC power to the transformer primary. The charging profile is determined by the ferroresonant transformer and boost capacitor. All of the Ferroresonant Transformer type chargers are based on the Trojan battery charge profile (attach-1).


In a nutshell, the amps should stay at 20+ amps longer and shouldn't drop to near zero, but that might be due to the mixed bag of batteries.

The charger circuit consists of the transformer, capacitors and diodes. Attached are how to check transformer and capacitor, plus a picture of face-plate and schematic. Diodes can be checked with a DMM.

If they check out good, than the problem is the batteries, but unless the capacitor has been replaced, it has very likely drifted out to specs. Must be replaced with same µF value.

Attached Images

	Charge curve.JPG (33.2 KB, 0 views)
	Transformer-Capacitor test - Text-1.jpg (367.7 KB, 0 views)
	Transformer-Capacitor test.JPG (66.2 KB, 0 views)
	TC-I Model 20484.jpg (302.0 KB, 0 views)
	Total Charge.jpg (191.4 KB, 0 views)

wjslam

Yeah the batteries are an issue for sure, but...you should have seen them when I got the cart. I cannibalized the two Duracells from my travel trailer to replace two 2016 Crown batteries that would only charge to 6.2 and were badly sulfated beyond repair. (Because of Trojan warranty issues with mixed batteries, I replaced the rv batteries with a pair of Trojan T-105s with 2 year warranty. New set of T-105s for the cart is $800 and I could not swing that right now.) So I'll limp this battery pack along until another one dies then replace all.

As for the charger, I REALLY appreciate the technical details because I have restored about 100 AM tube radios (mostly all american 5's) and have the equipment to handle testing, including an isolation transformer and variac.

I ordered a board ($43) and will conduct testing. Will post results when completed.

Attached Images

20191005_163003_small.jpg (53.9 KB, 0 views)

JohnnieB

Wow, haven't heard tubes mentioned for a while.

I used to teach in the USAF Bio-Medical Equipment Repair course back in the '70s and all the AF's basic electronics courses only covered solid state stuff while a lot of medical devices at the time had tubes in them, so we had to teach tube theory and tube troubleshooting to our students and I spent quite a bit of time teaching those two subjects as well as solid state and IC troubleshooting.

I still have Dyna-Kit PAS3 tube preamp and a pair of McIntosh Mk30 tube power amps (Same as Mc30's, but in DIY kits) that I power up when I play vinyl records, but I don't do that much anymore. (I could charge my cart batteries every day for a month on the AC power that setup takes to play a 3 minute song.) I've got most of my vinyl collection in digital format and have edited my favorites with a filter that makes them sound like they are being played through tube amps and another that reduces needle noise.

wjslam

Yep...tubes are great...90+ percent of every tube I've tested were good...made to last.

Thank you for your service in USAF. Much appreciated.

wjslam

Methinks I have found the (or at least a) problem. Note in photo that control board went bad (melted terminal connection) so op bypassed the board and connected hot from fuse to timer terminal B. I'm a bit hard of hearing but on my best day I could not have heard a bypassed solenoid click!

20mf capacitor tests at 20.5, so I'd call that good. Both diodes are good. Have not tested coil yet buy my bet is that it is good also.

New board is due 12/2. I guess I need to button the beast back up so I can use it til new board comes. Or is it ok to use maintainer as a veeery slooow charger until then? Cart is not used more than an hour tops per day right now.

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	20191122_164848.jpg (238.5 KB, 0 views)

JohnnieB

Only takes a minute or three to check transformer.

Clip an AC voltmeter on the transformer secondary leads attached to the diodes.

Ought to read 60VAC +/-5VAC without capacitor connected and 90VAC +/- 7VAC when it is connected.


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FWIW, the press in diodes can be replaced with 1N1184 or better stud mount rectifiers.


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As long as it charges the battery pack.