Battery problem

12.5 to 13 volts is lower than I would expect to see when being charged by the alternator or by the converter. I would expect the alternator to put out 14+ volts. The converter, depending on the converter, could be anywhere between 13.2 and 14.4 volts.

What is the voltage on the chassis battery when the RV is unplugged and the engine is running?

Bordercollie wrote:
Look for a short or some device that is drawing a lot of current. Check battery cable connectors and ground cable connection to frame. Battery may be useable.

Thanks. I did check the connections at the battery, which were fine, but I didn't chase down the other end. At any rate, if charging voltage is 12.5 to 13 volts with the engine running or plugged into a 30 amp connection, wouldn't that rule out a bad connection?

At any rate, I took the battery to Camping World today, and they said it's "probably" a bad battery. Or, they said, we're trying to run too much stuff at once while driving down the road. But all we're running is the radio/rearview camera and the refrigerator on automatic, which is running on LPG. It needs the battery on to do that, but surely that's a minimal draw. And if it's charging at 12.5 volts while going down the road, why wouldn't that keep it up? :h

Of course, they didn't have the proper battery, so we went to another local dealer for a battery and got to talking to him. He had the same concerns I have. Why wouldn't the charging system keep it up while driving, even on a marginal battery?

I have a new battery to install tomorrow, so we'll see.

Thanks for all the suggestions.

Edit:
Oh, by the way. Yes, a short is my concern. Since we had our first problem in July that didn't occur again until Friday, I fear we have an intermittent, infrequent short that's draining the battery. I guess if the new battery goes belly-up I'll know it's not the battery. But I hope that happens before the manufacturer's warranty expires.

Look for a short or some device that is drawing a lot of current. Check battery cable connectors and ground cable connection to frame. Battery may be useable.

I appreciate all the advice. I charged the battery overnight by plugging the rig into a 30 amp. I took the battery out and it's in my shop now holding 13 volts. If this were my car, I'd check for voltage drop by hitting the starter. So, I attached a small 12-volt compressor and checked for drop, and it only dropped to 12.8 volts. But maybe the compressor isn't enough of a draw to matter.

All cells were fine on water. I'm flummoxed.

Sounds very much like the battery is dead or has shorted cells. You could have it tested. A 12 volt battery that reads 12.5 volts is nearly dead. A good battery that has been kept charged properly should read over 13 volts in storage mode or when disconnected from shore power, on shore power it should read around 13.6 volts. With engine running, and charging via the engine's alternator it should read around 14 volts. Cleaning connectors at battery of corrosion and keeping electrolyte levels above the plates with distilled water helps prolong useful life of batteries.

Generally it would be covered under the battery manufacturers warranty, not the dealer.

Yes, I didn't make that clear. I know from the readings with the engine running or it plugged to AC with the battery switch in "Use" that I'm reading the charge voltage.

I couldn't see how it could be a problem with anything but the battery, except the first time it went down we were driving down the highway with the battery in "Use." But maybe there's a dead short in the battery.

I've left it charging, I'll disconnect it tomorrow and see if it holds, which, I expect, it won't.

And I'll pull the warranty papers and see what I can find.

Many thanks

Have you ever read The 12 Volt Side of Life?

It depends on what your warranty covers if the dealer will replace the battery.

Sounds like the battery is dead, at 8.5 volts! The 12.5 volt reading is from the alternator. The battery should have some sort of warrenty, you probably wont get full refund but should get something!