Chassis batteries charge

[ghspeer@sunocoinc.com]

I have a 5-year-old motorhome and the chassis batteries will not keep a charge. I need to use the battery boost button to get the vehicle started. Once started it runs fine. Two days later I tried to start it again and I still need to use the battery boost button. Is this a sign that the batteries are weak? They do not seem to hold a charge. The voltmeter reads 9 volts when I first turn the ignition key. When I press the boost button it goes to 10.5 volts, the engine starts and then it gradually goes to 13.8 volts and stays there till engine is stopped. It then drops back down to 9 volts in a day or so.

[wolfe10]

I have a 5-year-old motorhome and the chassis batteries will not keep a charge. I need to use the battery boost button to get the vehicle started. Once started it runs fine. Two days later I tried to start it again and I still need to use the battery boost button. Is this a sign that the batteries are weak? They do not seem to hold a charge. The voltmeter reads 9 volts when I first turn the ignition key. When I press the boost button it goes to 10.5 volts, the engine starts and then it gradually goes to 13.8 volts and stays there till engine is stopped. It then drops back down to 9 volts in a day or so.

Glenn,

Welcome to the FMCA Forum.

Yes, it sounds like bad chassis batteries if those are readings at the battery. If readings further "down stream", verify all connections are good and/or check readings at the batteries.

But, before scrapping them, verify that the water level is OK (if not maintenance free batteries) then bring them up to full charge with on-coach or external battery charger. Then have them load tested.

Brett

[Guest 2driftrs]

Hi, Glenn - - 5 years is probably good reason to scrap the old batteries, but you might want to try a few ideas first.

Definitely, like Brett said, check the water level if possible. You might also want to check your no-load current draw. You might have something hooked into the chassis electrical system that is drawing current even when the rig isn't running. Something as simple as a light in a basement compartment that's wired into the chassis side electrical that isn't turning off might kill your battery. In our rig, the electric steps are wired into the chassis battery, and the steps have a light that's on all the time when the steps are out. Fine when you're on shore power, not so good if you're not.

There's any number of web sites that can give you detailed instructions on doing a current draw check. Another way is to disconnect your chassis battery negative cable at the frame if you have a single battery system, and wait a few days. If the voltage is still up in the battery, then you have something pulling juice from somewhere.

Barry

[wolfe10]

There WILL be some draw on the chassis battery while in storage.

Things like the engine ECM, transmission ECM, etc.

So an alternative is to provide some small source of charging while in storage.

If stored with shore power, a Xantrex Echo charger, Trickle Charger, etc work well.

If not on shore power where you store it, even a small solar panel is usually enough to keep the chassis battery charged (not enough to charge a discharged battery, but enough to keep a charged battery up).

Deeply discharging any battery markedly shortens its life.

Brett

[-Gramps-]

It seems like you may have a dead cell. One of those cheap floating ball checkers does work. I have one and it told me that I had a dead cell. It would act like it was charging but it would not start the engine. Once I replaced it a whole lot of things started working better.

[ghspeer@sunocoinc.com]

Thanks for all the help. I did some more research and found out that the Coach Manufacturer put in smaller starting batteries than called for in the Manual. Manual requires CCA@ 0 degrees F to be 950 Minimum. Manufacturer but in CCA@ 0 degrees F of 760. I am having the batteries changed out to the correct ones later next week.