Community Forums

Open-Road-Pr · 11-15-2011, 02:29 PM

Our MH has been in the storage building for 3 weeks and today I went over to make the final moves, extend the levelers, disconnect the chassis battery and remove the coach batteries. It hasn't been plugged in over these past 3 weeks, but everything, including the propane detector, has been shut down. When I got the batteries home, cleaned up, the cells' fluid levels checked and hooked up to the charger, it indicated the percent of capacity as low! Without any draw on them since the shore line was unplugged three weeks ago, shouldn't they read a lot higher than low? These deep cycle batteries are just over a year old, checked regularly during the season and always on shore line power when not going down the road. Could I be having a problem in the coaches charging system? I know zip about electricity & things electrical.
The gauge on the charger said the voltage was 12.9 when I first hooked it up, went to 13 quite quickly, then to 13.1. When I came in from the garage the .1 & .2 were battling it out, so it seems to be charging up fine.
Sorry for my long windedness.
I would appreciate anything that you might think is wrong. Hopefully this is nothing big enough to worry about.
Thanks in advance.
Ron

OneRVer · 11-15-2011, 03:01 PM

I do not think you have a problem. As long as you are staying above 12.6 volts your batteries are fine. If you have a volt meter, check while plugged into shore power and see if you are at or above 13 volts. The convertor will charge slowly and only when needed.

gaugeguy · 11-15-2011, 03:17 PM

You didn't state your type of batteries and I'm no battery guru, but there are a couple of critical checks that must be done to insure your batteries are up to snuff.
Assuming you have the standard lead/acid batteries, the specific gravity is probably the single-most important test anyone can perform on a battery (other than making sure the cells are full with distilled water). Keep an inexpensive hydrometer on hand to make the specific gravity check.
Remember to fully charge your batteries. Use the hydrometer to check them often throughout the charging process. A fully charged battery will read 1.265 (+/- .007). I have seen some electrolytes as high as 1.300 when fresh, but that is unusual.
Personally, I never rely on any electronic battery checker other than a cold cranking amp tester.

I do not want to take up space here, but follow this link to get the low-down on battery care.

Battery Tutorial

Sorry to be so brief, but I have to take care of a minor emergency outside.

garym114 · 11-15-2011, 03:22 PM

A battery in good condition, no bad cells, with no loads connected should hold a charge for months. The batteries were not charged fully to start with, still had loads connected or not in very good condition.
Easiest way to check the batteries is with a good digital multimeter.

Open-Road-Pr · 11-15-2011, 05:20 PM

OneRVer, I hope you are right and there isn't a problem! Thanks for replying.

gaugeguy, Thanks for the info and the tutorial link was great.

garym114, Thanks for your reply and I really like the battery line in your signature.

Thanks guys,
Ron

Gary RVRoamer · 11-16-2011, 07:02 PM

Your coach is still drawing power with "everything shut down". For example, the circuit boards on the fridge, furnace and water heater are powered, waiting in case you flip a switch on. And the engine ECM is powered as well. It is not unusual for motorhome batteries to drain down quite a bit in 2-3 weeks. Mine is even faster - about a week.