More power problems

Interstate confirmed a bad cell on one battery and warranty replaced it. I'm crossing my fingers that all electrical issues are behind me!

bkenobi wrote:
The outboard cell dropped to 3.0v under load and returned to 12.12v. I'd say there's an issue with the outboard battery!

NO, really ?? :B

Sorry couldn't resist.
Good job with the testing.
Now it's off to the battery store.

And good luck getting them to "upgrade" with a warranty replacement, even if you pay extra.

If they are receptive to that, you might want to discuss two 6 volts if there is room. That often gives you more total capacity. And AGMs should give you longer life.

I think I've already said that's the plan. Interstate isn't open on Sundays and I was following other users suggestions on what to check first. Fwiw, I've already had the batteries in for testing at interstate twice and the dealership checked them once. Since they were brand new when I bought the camper, warranty would be appropriate. However, I want to be sure that pushing for the replacement is not a waste of time. I tried to get them replaced last time I dropped them for testing but interstate changed their mind at the last minute.

I appreciate all the suggestions even if it's perceived that I'm ignoring them.

There's a WHOLE bunch of suggestions here HINTING that you probably have a dead/shorted cell. I'm dying to see if you check for that or just keep doing what you're doing. :S

I've recorded voltage on both batteries for the last 2 days without anything connected (1 side of battery disconnected on each). I could post a table, but basically the inboard battery dropped from 12.65v to 12.54v and the outboard dropped from 12.65v to 12.40v. I wasn't convinced this proved anything conclusive, so I dug out my load tester. The inboard battery dropped to 11.5v under heavy load and recovered after removed. The outboard cell dropped to 3.0v under load and returned to 12.12v. I'd say there's an issue with the outboard battery!

I contacted Interstate today. They said they can warranty the batteries for me if one tests bad. If they decide they're bad, I may see if I can upgrade while I'm at it since these are the smallest available.

Have you used a hydrometer on the batteries to test each cell? Easy test to see if one cell is completely out of the ballpark. I've also used a meter to test individual cells by attaching a piece of copper wire to one meter lead and dipping the wire into each cell while the other meter lead is attached to a battery post. The reading should be 2.0 - 2.1 volts on the cell closest to the post the meter is attached to and another 2.0 - 2.1 for each of the next cells e.g., 2.1, 4.2, 6.3, 8.4, 10.5, 12.6. If you get to one (say 4.2 on the second cell) and the next one doesn't add up (say 4.6 0r 4.8V) then you've isolated the bad cell.

You really need to check the health of each cell of each battery. Sounds like an intermittent bad cell on one battery. It will show up with an individual cell test - quickly.

One bad/shorted cell on one battery will drag the other battery down - either to its level or close.

Get out there and test cells - then get back on here with your results.

bkenobi wrote:
* the batteries were charged until this morning (4 days) when I disconnected from ground power and drove to the insurance adjuster. The batteries should have been maintained during transit at 2A. The combined batteries were providing 11.8-12.0v after 2 hours unplugged.

Good chance one of the batteries has a shorted cell or has failed.
Should hold 12.6 fairly easy when charged and disconnected.

13.8 is a slow trickle charge and still 4 days should have them very close to full. If you have a portable battery charger maybe use it on one battery at a time.

Probably looking at 2 new batteries.

I would attack this with a clamp on DC ammeter. You need one that will measure DC current down to 20 ma or so - these are now available for less than $50. With this you can clamp it onto wires starting at the battery and working back towards the panel to see what (if anything) is drawing sufficient current to drag the batteries down. This is much easier and more informative than measuring voltages, which are a result, rather than the cause.

bkenobi wrote:
The batteries should have been maintained during transit at 2A.

From what source ?

IF the system really is designed to charge in transit, there usually is a solenoid that closes to charge the house batteries from the chassis alternator......but that would not be limited to 2 Amps.

Both of the used RVs I've bought recently had that solenoid bad. The last one called it a "battery isolator".

More tests are needed, including testing that "charging in transit" source that you think should be present.

P.S. The breaker tripping would tend to indicate that the converter/charger is drawing a REALLY high initial current, maybe indicating that the batteries are indeed weak.