Electric Golf Cart "running out of gas"

[RGrove]

The last couple of outings, my Cushman 36V has "run out of gas" very soon after pulling out of the cart barn. Last week, it made about two holes and seemed as though it was about to stop. I took it back to the cart barn and put it on the charger. The needle on the charger almost immediately dropped into the green, which is supposed to indicate a full charge. I left it on the charger anyway. I returned a couple of days later with a voltmeter and checked the battery back, read 35.2 volts. I did not have a chance to get it out and see how it was running then. Today I went back and checked the voltage, still at 35.2 volts. I could tell when pulling it out of the barn that it was probably not quite right but seemed better than last week. However, by the time I made it about halfway down Hole 1, I knew there was still a problem. I took it back down to the cart barn and checked the battery pack voltage again, now reading 33.4 volts. Probably driven no more than 1000 yards. Is nearly 2 volt drop normal?

Batteries were new this spring and have been taken care of. What tests can I run and what should I be looking for?

[scottyb]

A 36 volt pack is considered empty at 50% capacity or about 36.1 volts. The batteries shouldn't be drawn lower than this according to the Trojan website. 100% charged and settled (12hours after charging) should read 38.4.
It seems you may have a bad battery or a bad charger.

[gornoman]

Originally Posted by scottyb

It seems you may have a bad battery or a bad charger.

Agreed, 100%. My guess is charger. Can you borrow another charger from the cart barn?

Also, let's make sure the water levels are correct, and there is no corrosion present.

[RGrove]

Put the cart on my friend's charger this evening, will see how they look tomorrow.

[RGrove]

Thanks gornoman and scottyb for the input and advice. It seems my charger was indeed bad.

Here's the current situation with my old Cushman. Before putting the cart on a friend's charger, I checked batteries for water level and connections for corrosion. Didn't find anything other than a couple of cells being slightly low on water, which I replenished. All connections were corrosion free. After charging on friend's charger, all batteries were 6.5v except one that was 6.4v, total across pack was 38.9v. I drove the cart around the first 9 holes and it seemed like it was running like it used to before the recent problems started. No speed demon, especially up a grade, but certainly good enough to get me around and play golf.

After that excursion, the pack was down to 38.4v. I had an old spare charger that I put it on, but I'm concerned that charger is not working properly either, as the ammeter needle didn't move much when I plugged it in. Played about 15 holes today and cart seemed good. Forgot to check voltage before starting, but after playing, pack was a bit over 37v. Again when I put the cart on the charger, very little needle movement. Maybe it's OK, but just in case it's not, I'm going to start another thread asking about troubleshooting chargers.

Also, I noticed when checking the pack voltage after playing that the battery compartment was warmish. Not hot, and probably wouldn't have really noticed much but it was a cool evening. The warmth seems to be coming from the motor, which again was not hot. I could easily leave my hand in contact with the motor casing, but it was certainly much warmer than ambient. I'm assuming this is normal, but would like to know for sure. This motor is likely 35+ years old and I'm not really sure what I should be looking for in the way of abnormalities or how to test it's performance other than driving it around. Any advice about more definitely assessing the motor's condition would be greatly appreciated. I'm not adverse to having it rewound or even dropping the cash to get a replacement if I knew for sure it would make a significant improvement.

[scottyb]

If you can hold your hand on the warm motor for any more that 4 or 5 seconds it is okay.

It sounds to me like both your chargers are bad, your friends charger did a better job, at 37v the charger should jump to full out put for sometime which your does not.... you will get falsely high voltage readings within 12hrs of recharging.... so let it settle 12 hours then take readings. here is a chart to help you know what the readings should be, remember to keep the batteries in the top 50% of charge at all times for longest useful life according to Trojan Battery Co.