Charging house batteries

It's been plugged into the house on 15amp for about 48 hours and the voltage dropped from about 11 down to 8.6. Yes, the battery switch is on.

If the voltage is that low, then the battery is completely dead, and you are probably going to have to replace it. But, first you need to figure out your problem.

Nothing in the RV is on, so I can't figure out where it's draining from.

As I mentioned in a previous post, there are parasitic drains--alarms, radios, and maybe your jacks. These are on all the time, some may even be on when your battery switch is off. In the case of alarms this is a safety feature.

When I turn on the chassis engine and let it idle, the voltage jumps to around 13.3, so I hope that will charge it up to 12v and then I can use the house power line to maintain it.

With an 8 volt battery that could take all day. Idling your engine like that is not good for it. Are you plugged into shore power yet? If not you need to do so. Then you also need to check the voltage at the house battery to see if your converter is charging it. It should be reading 14v or more at the start. If it is an automatic charger it will taper off the voltage to about 13.2-13.6 when the battery is fully charged which may take all day.

If you are not seeing 14v+ when you plug into shore power, then you have a problem. Either your converter does not have a charger, or it is not connected, or it is not working.

Forester17 wrote:
Where would the converter be?

In my C it is under the refrigerator and the access panel is in the "stairway" going to the outside door.

Forester17 wrote:

Maybe the house batteries need to be up over 12 to be maintained by the house line? I'm confused.

Maybe but highly doubtful.
You are making this harder than it IS.

For some reason, your converter/charger has failed.....and the charging voltage is probably ZERO.

Once the battery voltage gets below 12 or so, it doesn't take much of a parasitic load to make it drop lower fairly fast.

You need to check connections and fuses for the converter/charger, but most often the charger itself has failed.

Your motorhome is likely to be equipped with a BIRD, a device which allows the engine and house batteries to be charged at the same time, from either shore power or generator. If you can't find it, use a multi meter to test dc amps/voltage with and without power.

All good advice on keeping the batteries up to charge.

Regarding the "interface cable". If your rig is like mine, you have Bigfoot levelers with the control panel located on the entry step wall. If the lights are blinking on the control panel, you will need to rest the system. To do this, you remove the 4 screws holding the control panel and pull the panel out from the wall. On the back of the panel, you will see the "interface cable" that plugs into the back of the panel. Unplug the cable, wait a couple of minutes, plug the cable back in. You lights on the control panel should not be blinking anymore. Replace the panel.

You will find a lot of help on the Bigfoot Support Page.

Holy Cow!!!! Nobody mentioned to check the WATER LEVEL in the battery first!!!!
Unless it's a sealed AGM. Start there first. Then get a 12 volt (cigarette type) plug in battery tester. Plug it in a house connector and it will tell you what the state the battery(ies), then start the generator and see what the generator is putting out. Somewhere 13.2 to 14.0 volts. Then shut off the generator and start the engine and see what it's putting out. Then report back and we'll go from there.

Probably integrated into the power distribution panel where the breakers and fuses are located.
Could be simple as a tripped breaker.

Where would the converter be?

Need to check the converter. Verify 120vac in and 13.6vdc out. Get in there with your volt meter and start poking around.

It's been plugged into the house on 15amp for about 48 hours and the voltage dropped from about 11 down to 8.6. Yes, the battery switch is on.

Nothing in the RV is on, so I can't figure out where it's draining from. When I turn on the chassis engine and let it idle, the voltage jumps to around 13.3, so I hope that will charge it up to 12v and then I can use the house power line to maintain it.

Maybe the house batteries need to be up over 12 to be maintained by the house line? I'm confused.