Ezgo Marathon - Constant Drain and Zero Power?

[IFixPoolLights]

So I've been having some real performance issues over the last few weeks and I found a weak battery and replaced that and another that was borderline. Before this happened the wife & I would do a 3 mile cruise (neighborhood) with regularity and had no issues.

Replaced the charger, gets close to 42.8 to 44 volts while running, then more recently I can literally watch on a digital gauge go below 34 volts in a matter of 10 mins. If I take it down my driveway it just went from 40.2 (off the charger) to 36 in 2 mins. No hills or load, barely made it back to my garage.

I have been disconnecting the cables between charges to see if there is a short somewhere - old resistor style.

Just today I turned the key off and was seeing how my meter would read against the resistor (I think something is amiss because it gets VERY hot, much hotter than before).

When I connect the #4 resistor (back in black attached) I get a reading of 19 volts - no key is on. Does not seem to matter whether the key is off.

I suspect the performance and this are related but not sure where to start.

I have a Curtis controller and wondering if it's just time to swap it out. Cart isn't fancy but we like it.

Would love some guidance here - thanks in advance!

[bronsonj]

It sounds to me like bad batteries. You've already had two batteries go and if you just replace those two they will age much faster than the rest. They will be overcharged when charging because the older batteries will take longer to charge so your two new batteries will act like old ones really soon.

To prove the issue, charge the batteries then leave the charger disconnected and don't drive the cart, 10 or 12 hours later measure each battery individually again. Assuming they all measure reasonably high and reasonably close to each other (like 6.36v and 6.34v) then drive the cart with the voltmeter hooked to the pack.

If the batteries drop on their own, they are shot. If one or more drops out when you drive the cart then the batteries are shot.

[IFixPoolLights]

I'll give it a shot - the batteries are not yet a year old.

Any idea why a resistor cart would draw 18 volts while nothing is on? I'm going to try to see where it's drawing.

All the batteries (except the ones replaced) would go to 6.7ish consistently - but I agree that's a great place to start.

Thanks!

[JohnnieB]

Originally Posted by IFixPoolLights

I'll give it a shot - the batteries are not yet a year old.

Any idea why a resistor cart would draw 18 volts while nothing is on? I'm going to try to see where it's drawing.

All the batteries (except the ones replaced) would go to 6.7ish consistently - but I agree that's a great place to start.

Thanks!

Unless otherwise stipulated, all voltage measurements should be made with Negative test lead (Black) connected to the battery pack's main negative terminal.

In the picture, the negative test lead is connected to post 4 on the coil assembly and the positive lead is on an unidentified battery post. The meter is showing +19.0V, so it would be a more positive point electrically than the #4 post on the coil assembly, but I cannot tell if it is the main positive terminal or the positive terminal somewhere in the middle of the pack.

What voltage do you get on post 4 when black lead is connected to battery pack's main negative terminal?

[bronsonj]

Originally Posted by IFixPoolLights

All the batteries (except the ones replaced) would go to 6.7ish consistently

6.7 must be while it is on the charger or immediately after the charger is removed. 100% state of charge for a 6v battery is 6.37v and 6.05v is about as low as most people will drain their batteries for longevity. This is assuming you have Trojan batteries or one of the many Trojan clones. I think U.S. Battery has a slightly different voltage IIRC.

But the first thing to do is anything JohnnieB tells you... He's forgotten more about carts than I'll ever know.

[IFixPoolLights]

Originally Posted by JohnnieB

Unless otherwise stipulated, all voltage measurements should be made with Negative test lead (Black) connected to the battery pack's main negative terminal.

In the picture, the negative test lead is connected to post 4 on the coil assembly and the positive lead is on an unidentified battery post. The meter is showing +19.0V, so it would be a more positive point electrically than the #4 post on the coil assembly, but I cannot tell if it is the main positive terminal or the positive terminal somewhere in the middle of the pack.

What voltage do you get on post 4 when black lead is connected to battery pack's main negative terminal?

I'll check that later today and

Noted on the battery - this morning was 6.2 after being off the charger with no use since saturday. It was probably done either on the charger or just off. The 2 weak batteries (1 was really bad) and they all seem to be at about the same voltage. I'll follow Johnny's suggestion and post back later.

[bronsonj]

Originally Posted by IFixPoolLights

this morning was 6.2 after being off the charger with no use since saturday.

In two days, without use your batteries dropped to 70% (assuming 6.20v and not 6.29v) State Of Charge. That seems like a big drop for not being used.

Do you have a meter that'll read to the hundredths? 6.19v is 70% and 6.25v is 80%, so just a few hundredths really make a difference.