I bought a 100 amp hour deep cycle battery about 18 months ago, and it seems to be failing. It will only remain above 12 volts in the camper, for about 12 to 14 hours, with normal camper use. When it was new, it would last for 2 or more days. This is without using the forced air furnace, but water pump, lights, (and all the background circuits -- alarms and so forth...) I generally run the happijacs and slide-out with the truck engine running.I charged -- then disconnected the battery last fall -- in April it was still very close to 13 volts, so it held it's charge well over winter. I'm wondering if I have a short somewhere in the camper that is sucking the battery down?How do you measure the resistance of the camper's electrical system? I have a pretty good ohm meter, but don't know what settings to use, or what to look for. I guess I'd check the various systems of the camper, by measuring resistance at the battery cables, by removing all the fuses, and then inserting them one by one, and checking resistance for each?Is there a definitive test for batteries, that will measure their ability to last under load?Any advice will be appreciated.

You might consider performing a parasitic draw test on the system using your multi meter. All items turned off, connect your ammeter in series between the Negative post and the Negative battery terminal. I don’t know what an acceptable draw is on your rig, perhaps someone with a similar set up can tell you. It is difficult to use an Ohmeter to test your system, but you can perform Voltage drop tests to check for poor connectors, corrosion, etc. But that’s another “how to”story.

Do you have a 3 way fridge, rare but still aroundFridge on 12v instead of lp will suck a battery like a vampireLeft a light on in the storage bay?Emergency brake pin pulled out ?Water pump cycles a lot ?

What is the charge profile being used to charge?repetitive undercharge is what I suspect from here ;)For now take it to a auto parts store that does a free charge/test.Find the makers charge profile and mimic! Solar makes a good maintainer getting the batts to 14.6v daily charge.

“Solar makes a good maintainer getting the batts to 14.6v daily charge”You bet it does and my “maintainer” is a small solar panel and WindyNation 10 amp twenty dollar weather proof PWM controller.

Battery Failing Prematurely | Good Sam Community

SoundGuy
Explorer
Jun 11, 2018
Old Islander wrote:
We have a 2-way fridge with tiny indicator lights only. No light in storage area. Water pump is tight -- might run for a second or two, every 4 or 5 hours. Not sure what the emergency brake pin is? This is a slide-in camper on a truck.

What make / model of fridge? Does it have a climate control heating element and if so have you ensured it's turned off, for if not it will significantly draw down your battery reserve. You also need to ensure that any other parasitic draws are turned off, in some cases requiring you to install kill switches, such as in a stereo. Obviously, as a truck camper there won't be any brake system break away switch - but that wouldn't have been mentioned if you'd told us this was a TC. :R
wa8yxm
Explorer III
Jun 11, 2018
No description of RC or of the Converter.

The Emergency Brake pin is the break-a-way cable the plastic pin on the trailer end of the cable.

IF you have a older RV (I see you've been RVing since 1983, I've been doing it since 1978 and some of those older converters were..... JUNK.

you might have a battery killer

Edit 100 amp hours means a Group 27 or 29. or wal-mart's rating on a 24 (Wal-mart cheats on their ratings read carefully)

Most of these are MARINE/deep cycle. not really deep cycle. you treat 'em like a deep cycle (Take 'em down to 50%) they die young

Try a GC-12.. A bit more amp hours true deep cycle.
Or two GC-2 in series (Six volt two make 12) Lots more amp hours and true deep cycle.
Old_Islander
Explorer
Jun 11, 2018
MrWizard wrote:
Do you have a 3 way fridge, rare but still around
Fridge on 12v instead of lp will suck a battery like a vampire
Left a light on in the storage bay?
Emergency brake pin pulled out ?
Water pump cycles a lot ?

We have a 2-way fridge with tiny indicator lights only. No light in storage area. Water pump is tight -- might run for a second or two, every 4 or 5 hours. Not sure what the emergency brake pin is? This is a slide-in camper on a truck.
Old_Islander
Explorer
Jun 11, 2018
amxpress wrote:
You might consider performing a parasitic draw test on the system using your multi meter.

Thanks for this... Googled 'parasitic draw test' and found a number of sites with excellent instructions for doing this. I'll try it over the next few days.
BFL13
Explorer II
Jun 10, 2018
"I charged -- then disconnected the battery last fall -- in April it was still very close to 13 volts, so it held it's charge well over winter. I'm wondering if I have a short somewhere in the camper that is sucking the battery down?"

It "held its charge" with no load on it, but collapses under a load. Usually means the battery is sulphated, as noted above re previous undercharging.

It is still possible there is an unknown draw in the camper. Your Happijac problem might be related. Is it possible for the jacks' power unit to be stuck "on" when you think it is turned off?
Lwiddis
Explorer II
Jun 10, 2018
“Solar makes a good maintainer getting the batts to 14.6v daily charge”

You bet it does and my “maintainer” is a small solar panel and WindyNation 10 amp twenty dollar weather proof PWM controller.
red31
Explorer
Jun 10, 2018
What is the charge profile being used to charge?
repetitive undercharge is what I suspect from here ;)

For now take it to a auto parts store that does a free charge/test.
Find the makers charge profile and mimic!

Solar makes a good maintainer getting the batts to 14.6v daily charge.
2oldman
Explorer II
Jun 10, 2018
What brand of battery?
MrWizard
Moderator
Jun 10, 2018
Do you have a 3 way fridge, rare but still around
Fridge on 12v instead of lp will suck a battery like a vampire
Left a light on in the storage bay?
Emergency brake pin pulled out ?
Water pump cycles a lot ?
amxpress
Explorer
Jun 10, 2018
You might consider performing a parasitic draw test on the system using your multi meter. All items turned off, connect your ammeter in series between the Negative post and the Negative battery terminal. I don’t know what an acceptable draw is on your rig, perhaps someone with a similar set up can tell you. It is difficult to use an Ohmeter to test your system, but you can perform Voltage drop tests to check for poor connectors, corrosion, etc. But that’s another “how to”story.

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