Itasca Spirit Batteries losing charge

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.

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.

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

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