Charger not turning off

[cpbergie]

I have a 2015 ezgo rxv with 4 12V batteries that are about 1 year old. Recently, the charger would not stop charging unless i left it on for an extremely long time, and the batteries are always gassing. Ive checked the water levels and they all are fine, though they were low after a week of excessive charging and gassing. I borrowed another charger from a friend, and it does the same thing, so it seems to be the batteries or something else.

The full pack tests at 53V once i unplug the charger. Each individual battery is around 13.0 - 13.2.

Is there something else i can test with regards to the batteries? Is it possible the chargers are not getting the same reading and not shutting off? Is there a way i can test that?

[LukeL]

It should be about 10V higher than that when finishing charge. 63-64v is not uncommon. How long are you leaving it?

[cpbergie]

I leave it overnight, but have been unplugging the charger after about 5-6 hours. Should the batteries gassing during every charge? It never did that before.

[LukeL]

Sometimes some gassing is normal. Leave it until it gets to around 62-64v. If it still doesn’t shut off after a bit, you might have a problem.

[cpbergie]

Would it read 62-64V with the charger plugged in, or should I unplug it before taking a reading?

[LukeL]

With it plugged in as the charge is finishing.

[cpbergie]

I let it charge overnight, checked it this morning and the charger was flashing red (fault). The reading was 51 for the pack. Drove around for 10 minutes and it was still reading 51. I just plugged it back in to try and charge it again. Not sure what else to check now.

[JohnnieB]

What error code is flashing? (list attached)

What make/model are the batteries?

[cpbergie]

I unplugged the charger before i realized i should have counted the red flashes. Based on what i saw with the other charger never turning off, i might have been that the charge timed out.

They are Trojan 1275 (H8 is the date stamp).

The charger has been back on for about 2 hours now, the batteries are already bubbling/gassing. They are reading 57V with the charger plugged in.

[JohnnieB]

You might have a battery with a bad cell.

While the charger is connected and turned on, measure the ON-Charge voltage of the individual 12V batteries.

They should each read exactly 1/4 of the 48V battery pack's On-Charge voltage at the time.

If the pack voltage is 57.0V, each battery ought to read very close to 14.25V and the difference between the highest and lowest shouldn't be much more
than 0.1V.

What we are looking for is a battery that is upwards of 2V lower than the other three.