Itasca Spirit Batteries losing charge

[JK_Coney]

My 2000 Winnie Itasca Spirit's house batteries won't hold a charge longer than a few days. The batteries are only 2-3 years old. They will accept a charge OK overnight and when I run the engine for a few minutes. When plugged in the RV gets power just fine. I charge up and then shut down the inside battery power switch, but after a few days they're dead. I don't see anything else that's on inside? Any ideas? Thanks!

[pnichols]

Gonzo42 wrote:
I'm anyone. Please post.

Ask and ye shall receive.

The last one in this list (DCM0100L) is the 12 volt true deep cycle battery model that we have two of (for a total of 200 amp hours) in our Class C RV - they're of course hooked up in parallel and they'll both be 8 years old come this fall:

http://www.interstatebatteries.com/content/product_info/wheelchair_spec.asp

Here's the .pdf for the DCM0100L model opened up for you. Note from this detailed spec that the recommended float voltage for this model is exactly what most stock single voltage RV converters put out. We switched to these batteries years ago instead of changing out our perfectly good Parallax converter:

http://www.interstatebatteries.com/content/product_info/specs/MKT0030-01_DCM0100L_09_CLS.pdf

[Gonzo42]

I'm anyone. Please post.

[pnichols]

Dakzuki wrote:
Virtually all 12 volt batteries in RVs are not true deep cycle batteries (unlike 6 volt deep cycle) so they are more likely to fail prematurely.

Not true.

There are true deep cycle 12 volt AGM batteries available in the common automotive sizes. I have a couple in our Itasca Class C RV and can post a website showing their specs if anyone is interested.

[JK_Coney]

Here's the latest. I plugged in overnight, and when I unplugged there was no power at all. The house batteries weren't accepting a charge. When I started the engine for a few minutes and then shut off, the batteries did indicate that they were charging up. So apparently they aren't getting charged from the external supply. I did flip the inside battery switch to on. HELP!

[Dakzuki]

Bobbo wrote:

wwest wrote:
Common problem with battery's connected in parallel, use 2 six volt battery's in series.

This has nothing whatever to do with it. If there is a bad cell, a pair of 6v batteries with a bad cell is not an improvement.

As a matter of fact, with a pair of 12v batteries in parallel, one with a bad cell can be taken out of service and you are still up and running on one battery.

Virtually all 12 volt batteries in RVs are not true deep cycle batteries (unlike 6 volt deep cycle) so they are more likely to fail prematurely.Very good info here.

I went full boogie and put in 6 volt AGM Lifelines.

[JK_Coney]

Thanks for all the advice. I'm on it...

[tatest]

If you've got two, try each separately. Usually when one of my two batteries fails (cell short, reduced capacity from being sulphated or partially drying out) the bad one will quickly drag down the good one, even with minimal load.

If I can find out which of the two batteries is the better, I can make do with that one alone until I get a chance to replace them both as a matched set.

That they charge to full voltage, even to "full" by measurement of specific gravity, does not mean that they are in good condition. A battery, if not shorted, with capacity reduced to as little as a tenth of what it was new will still charge to the full charge voltage. It will get there very quickly if there is not much effective plate area to charge. Condition, current effective capacity, has to be measured by charge/discharge testing.

[Bobbo]

wwest wrote:
Common problem with battery's connected in parallel, use 2 six volt battery's in series.

This has nothing whatever to do with it. If there is a bad cell, a pair of 6v batteries with a bad cell is not an improvement.

As a matter of fact, with a pair of 12v batteries in parallel, one with a bad cell can be taken out of service and you are still up and running on one battery.

[wwest]

Common problem with battery's connected in parallel, use 2 six volt battery's in series.

[Dakzuki]

Good ideas. Since you have two batteries, charge them both disconnect them from each other (and the RV) and them check them individually.

If they are in fact defunct here is your chance to upgrade.

[Gonzo42]

I agree with all the aforementioned. If you have an Autozone nearby, they will both test and recharge your batteries for free. Other auto parts stores may do the same. If OK, then do the check when the batteries are disconnected for a few days. If then the batteries look OK but then discharge while connected you probably have a small current draw where you shouldn't. It will then be a long process of troubleshooting to find the leak.

I had a bad cell in one of my house batteries while in Yosemite last march. The generator couldn't keep the batteries charged. Since we were snowed in it was a bit of a problem.

[wcjeep]

The battery could have a partial short internally. You may have developed a different problem too. What is the battery draw with everything off? Everything off with battery disconnect turned off? Expect some draw because of stereo clock, propane and CO detector. Should be under 1amp draw.

[Desert_Captain]

Get a Hydrometer (about $10 at the auto parts store), and check both batteries. It sounds like you have a bad cell (perhaps more than one), that is pulling them down. If so it will take a charge but once a load is applied the batteries will quickly discharge.

What you should see is that all of the cells have approximately the same reading (specific gravity). As long as they all read about the same level you are fine. If one cell reads significantly lower than the others it is bad and there is nothing you can do but replace the battery. One bad cell can easily pull down both batteries if they are wired together.

:C

[tenbear]

First, I assume you are doing the necessary battery maintenance, checking the water levels, etc.

The OEM battery disconnect switch may or may not remove all the loads on the battery. I suggest that if you don't have a means of measuring the current being drawn from the battery, that you disconnect the negative lead from the battery after it is fully charged and see if the battery still discharges in a few days. If it does then you have a battery problem, if not, you are still drawing a significant current from the battery with the OEM disconnect switch disconnected.

It may also be that your batteries are not being fully charged when you think they are. :h