How to keep battery from running down?

[Dave Jenkins]

We normally stay a month or more in each place we visit. How do I keep my battery from running down when my trailer is parked? I think my current (OEM) battery, not quite two years old, is shot.

[sande005]

I assume you mean you are away, and the trailer is parked without power? Fully disconnect the battery - the installed switch doesn't disconnect everything, Either take the wires off of one terminal, or install a separate switch that will completely disconnect everything.
The installed leaves on safety items (emergency brakes, smoke/propane detectors) convenience items (clock and presets in the entertainment center), and perhaps a few other small items. But over time, those small items drain the battery.
If you do plug in for the time, make sure to leave the switch on - if off, the battery won't recharge when it needs it.

[Dave Jenkins]

No, we were not away. The battery ran down while we were living in the trailer and connected to shore power.

[Hoopy Frood]

That shouldn't happen, obviously. You may have the Battery Disconnect Switch turned to "OFF" which would not allow the converter to charge your batteries, unlikely as most other 12V stuff won't work either, or the converter is not working as it should. That could be because the fuses are blown, or the converter isn't plugged in, or the circuit breaker that powers the converter has tripped.

Time to get out the VOM and start checking the voltage at the battery/ies and see what kind of voltage the battery/ies is getting from the converter and go from there. Obviously check fuses and circuit breakers first.

[dryfly]

Just for info, assuming you are parked and hooked to shore power how did you find out your battery was down? As Hoopy said, disconnect the battery and measure what voltage the converter is supplying to the battery.

[sande005]

The one other outside possibility - there might have been a time or two in the past where you weren't plugged in and ran the battery way down. That can dramatically shorten its life, which shows up in not being able to maintain capacity....I killed my first ever by over discharging just once....

Was if fine before, and now you are starting to see it in the last few months, or has it always been a problem in prolonged stays?

The OEM batteries are supplied by the dealer, many of whom are prone to putting the smallest, cheapest they can get away with. So it may be just its time....

If you do go battery shopping (and I assume you aren't going to look at lithium's), size matters - the bigger the greater the capacity. Heavier means more resistant to mild abuse. Look for the "RC" (Reserve Capacity) number. Higher is better. Stay away from ones that only mention "CCA" - that's for engine starting. High CCA means low RC, generally. Try and avoid "dual purpose" starting/rv/marine batteries - that's where Optima's fall down. They try to be both, and aren't so great at either.

[Dave Jenkins]

Dryfly asked "how did you find out your battery was down?"

After being parked here about a month, I tried to re-level the trailer. The leveling control was off. Also, the lights inside the storage compartment, which are supposed to come on automatically, were off.

[sande005]

Dryfly asked "how did you find out your battery was down?"

After being parked here about a month, I tried to re-level the trailer. The leveling control was off. Also, the lights inside the storage compartment, which are supposed to come on automatically, were off.

For most RV's, when plugged in the converter supplies almost all of the 12v power needed, by itself. Some don't even need a battery installed - but that can be variable. If extra oomph is needed, the battery can supplement what the converter is supplying. Other times it just sits and gets whatever nominal recharge it needs. Were you unplugged from shore power at the time? What position is the red power switch at (ie - if you can pull it out, it is "off")? If unplugged, all lights (and all other 12v things - water pump, fans, stereo/dvd, etc) should have been weak or dead too if the battery was going out. If plugged in to shore power, then all lights should be working, and likely even the control center, even if it can't get enough power to relevel. There may be something more mysterious afoot than just a bad battery.

[dryfly]

I can't imagine tackling a battery problem without 1) knowing the output charging voltage from the converter 2) having the battery load tested. By eliminating these issues first you can start working downstream of the battery looking for issues, and saving a lot of time.

[Dave Jenkins]

Unfortunately, I know squat about electronics.