Powerwise 2 capacitor

paramedtim

I bought new Continental batteries for my 2006 series cart. I installed them today and when I checked the voltage it was anywhere from 6.34 to 6.35 for each battery and total for the pack was 38.1. I plugged my charger in and it only showed 3 amps on the ammeter. I checked the voltage with the charger running and it stayed the same. I could hear it humming and the relay clicking on. I did the Lester troubleshooting and came up with a bad capacitor. Fuses are all good, the diodes check out good. Only thing I didn't do was jump the timer circuit because I could here it humming. I also checked the voltage at the charger cord without it being hooked up to the cart and it was showing 44 volts if I remember right. I'm just double checking with y'all to make sure I did it right before I order parts. I can only find 3 mfd 440 vac capacitors locally so I'm gonna have to order. Did I do it right?

BGW

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paramedtim

ScottyB or JohnnieB, did I troubleshoot it right?

JohnnieB

With your battery pack being so close to a full charge, the initial amps will be low. Just let the PW II charger run until it shuts of automatically.

It'll stay at that 3A (or so) rate for several hours. (10? 12? maybe more? - might even have to restart the charger is it times out rather than shuts off automatically) And the batteries will gas quite a bit, so keep an eye on the electrolyte level. (Don't let the plates get exposed, but don't fill to proper level until after the batteries are fully charged.)

Just jumping the relay and checking the DC voltage doesn't mean much since the transformer is part of a ferroresonant circuit (the capacitor is the other part) and is unloaded.

The way to check is to measure the AC voltage across the two secondary windings feeding the diodes. Just attach the leads of your ACV meter to the wires from the transformer that connect to the two diodes and measure with and with out the capacitor attached to the transformer. Note: charger is not to be connected to cart, so relay has to be jumped.
Without Capacitor it should read about 80 VAC and with it it should read about 100 VAC, depending on your AC Power line voltage.

If you don't get about 80 without, the Transformer is bad.
If you don't get about 100 with, the Capacitor is bad.

paramedtim

Thanks, I'll check it that way. I just used the ohm meter across the capacitor terminals like it said in the manual and it didn't move the meter. With my old batteries that were sometimes pulled down to 35 volts it would only show 5 amps also.

JohnnieB

1. DMM's on Ohms update too slow to show a flicker on a big Capacitor. The old analog meters are better for checking capacitors and potentiometers.

2. That's a different story. 3 amps on a new set of batteries that are near full charge sounds about right, but 5 Amps on old batteries with only about 20% SoC is something that needs to be checked out.

With the battery pack at 35V the PW II should have jumped to 25-30A and stayed there for about 30 minutes or maybe a little longer. Then tapered off to around 8 or so, and maybe down to 5 in a hour or three.

When everything is working right, the transformer/capacitor combination boosts the voltage to the diodes until about 25A of current flows through the Battery Pack. When the battery pack voltage starts climbing into the low 40's, the current flow tapers off to about 1-3% of the AH capacity of the battery (AH @ 20 hr rate) and stays the until battery pack voltage reaches 44-46V and the charger turns off.

Here is the Trojan charge profile and a PW II tracks it pretty close.
I am amazed that Lester (PowerWise, Total Charge and many others are copies of the original Lester design) was able to do it with just a specially wound transformer and a matching capacitor.
Note the lowest SoC is 20% and no times are given. (Read text below graph)

JohnnieB

If the Cap is bad, you need a 3 mfd, 660 VAC Motor Start Capacitor. Check with your local electrical and HVAC supplies.
That is a fairly common size and you ought to be able to pick on up for less than $10. EZGO wants $45 for them.

I saw one on-line for $2, but you gotta add shipping, etc.

simple man

I've charged them with a 9V battery and then using dc volts scale see how long the capacitor will hold a charge. This isn't accurate, but it will tell you if it's good or bad. If it will hold a charge for 15 seconds at 9V and slowly drop in voltage, it should be Ok. A bad one won't even hold a charge long enough to test it, or it drops to 0 in just a few seconds.

paramedtim

I used an old analog voltmeter to check it. I was an HVAC/Commercial Refrigeration Tech for 20 years before I became a paramedic so I remembered to use an analog meter to test it. I called some of my old suppliers yesterday and they all had 440 vac but not 660. I called the EZGO guy in Lubbock today and he said he had some for around 20 bucks. He said if I brought the charger he would check it for me for just buying the part from him. He's 45 miles away but oh well. I feel better having him double check it. BTW the one that came out was a 4 mfd. Would that have been too much? I guess it had been changed before.

JohnnieB

That's a good question.

I know that upping the capacitance in a parallel resonate circuit by a third would shift the resonate frequency away from the 60 Hz AC line frequency the charger is designed to operate with.
But how exactly that would alter the charger's charge profile, I do not know.

My guess is, if it boosts the unloaded AC voltage to the diodes from ~80VAC to ~100VAC, it ought to be in the ballpark.

If the dealer in Lubbock has both 3 mfd and 4 mfd, and is cooperative, it would be interesting to see what the boost is for each.

FWIW: A 4 mfd is used in a 48V Lester, but the transformer has a different turns ratio going to the diodes.

paramedtim

I took it to the EZGO dealer today. It was the capacitor. Put a new one on and its charging like a champ. He said the same thing about the 4 mfd being for a 48 volt. He went back with a 3 mfd. It was a fleet cart before I bought it so that may have been what the course it came from had on stock. I dunno. I just know its working. So now to get my batteries broke in and play some golf. Thanks JohnnieB and simple man for the help.