Home Batteries Problems

[Coyotetr]

I have a Forest River 25 foot RV on a Mercedes Sprinter Chassis and for some reason, the home batteries wont keep a charge for more than 10 minutes. It used to be we could go almost 3 days before we had to use the generator, now the home batteries go dead in 10 minutes. I put in a new house battery but to no avail. Has anyone else had this problem?

[bluepill]

1. Can you be more specific as to "Won't keep a charge"?

2. Have you tested voltages with the charger running?

3. Do you rely on the engine alternator or the charger to top off your batteries?

[vsheetz]

If you put in a new house battery and the problem persists, makes one wonder if the battery charger is working correctly. With a voltmeter check the voltage at the battery with and without charging occurring. A increase of a volt or so (more, if the batteries are low on charge) should be experienced when charging.

[FIRE UP]

Mr Sheets has a point in that the charger may not be bringing the "House" not "Home" (no biggie) batteries up to par. But, one more thing, is it possible that there is some major draw on them that you're not seeing. As in, maybe compartment lights (all of them) on, or, there's something else on and or, a direct short some place. I also would figure that, if your house batteries were in good shape and at full voltage, that if something were to take them down that quick, something should almost be SMOKING!

That's a serious draw in such a short time. It will be interesting to find out what the cause is/was.
Scott

[TQ60]

First things first.

Get a volt meter and measure the voltage at every battery at the posts while not plugged in or engine running.

Next plug shore cord in and verify disconnect switch in correct position and repeat.

Next start engine and repeat.

This will tell us the standing voltage as well as charging voltages for both battery systems under parked and driving conditions.

Write them down and report back.

[bigben]

I had similar problem - lasted more than 10 minutes but quickly dropped. Broke out my trusty hydrometer - 1 battery dead, 1 battery very weak, 2 batteries weak. Now this was a self-inflicted gunshot wound - I'd added 2 new batteries to increase the bank from 2 to 4. About 2 months later, I replaced one of the original. After 5 months, nothing is holding a charge. Moral to my story, replace them all at once.

I'd test the batteries with the volt meter and hydrometer to see the status of each. If the batteries test good (I'll bet they don't), pull fuses 1 at time to find the draw.

[TQ60]

Batteries are like a plastic cup of water.

Take a milk jug full of water and poke a small hole in it and then fill the cup.

The top op the cup represents full charge voltage.

This represents charging and it takes time to fill.

Now poke small hole in the cup and this represents load.

Cover hole with finger and that is disconnect switch.

Start with empty cup and cover hole and fill whole observing time.

When full remove finger and allow to drain again noting time.

Now fill cup with sand and repeat.

It takes less time to fill but still will fill up and takes less time to drain.

But also note it drains with less intensity for that time as well.

The sand represents sulfated plates or sulfation of the battery and this is a normal thing over time and can be worse depending on how used.

Equalization or "boiling" a battery may restore some.

Specific gravity and voltage indications usually show perfectly fine battery but sulfation blocks the plates therefore effectively makes them much smaller reducing their effective capacity.

This matches the symptoms you are reporting.

[bigben]

In my case, the specific gravity showed the 3 various levels I reported. After about a 6 month period specific gravity was in the tank on each. UUGGHH. Learned a lesson. Piece meal replacing doesn't get it done.