We are camping this week and I'm having trouble with the batteries on the trailer. I have 2 12V batteries in parallel. Both batteries are 4-6 years old and I have not had any issues with them to this point.One battery was on the trailer and it died after about 2 days of usage for just the refrigerator (the fridge was on gas so the battery only needed to power the thermostat, no one was using the trailer so the only other things that would have been on were the CO detector and the radio vampire draw. The battery was switched out with a second battery that was fully charged and that lasted about a day or less. So today around 3 PM I took one battery that tested at 12.3 volts and another that was at 12.9 volts and set them up in parallel which I have done many times before and always get a few days of usage out of them but about 4 hours later they are already both down to 10 volts.I don't think it's a battery issue because they are both doing the same thing regardless of how they are hooked up and it would be pretty coincidental that both batteries went at once. It seems like something else is drawing the power down pretty quickly. I've dry camped like this for years and never had this happen before.Any ideas? Thanks in advance.Mike

I would look at the water heater. I would also try to measure the current draw on the batteries. It seems something has changed to increase it batteries current draw.

First, a 6 year old battery is pretty old, next, connecting the 12.3v battery and the 12.9 in parallel bassically got you a pair of batteries limited by weakest battery in the pair.When batteries go bad they drain much faster than when new so it's likely that your actual amp hour capacity left in that bank is much less than when new and what you were used to.The 12v draw on a Dometic fridge is more than the thermostat, it's the ignition circuit and the 12v anti condensation heater that most Dometic frigs have. Open the frig door and feel the frame between the frig and the freezer...if it's warm it's running on 12v. There may be a switch for it up under the top power panel (you will need to open the freezer door to see it but many do not have a switch, the heater is always on. Water heater, mine has about .5 amp current draw.Plus there's the parasitic load of the co2 detector and possibly a few other things...usually between .5 and 1.5 amps.If I were to guess I would guess old batteries.

Hi,Does the trailer have electric breaks? Is the breakaway switch set up to be "off"?

Draggo wrote: Both batteries are 4-6 years old and I have not had any issues with them to this point.Time to replace both. It's better to replace them before this sort of thing happens. bill-e wrote:Water pump? even when not pumping if it's turned on there is a current draw.No there isn't.

Old batts wont keep the amps needed thats your problem nit the volts

Need Battery Help ASAP | Good Sam Community

2oldman
Explorer II
Jul 25, 2016
2- 12v or 6v June 2013
12v vs 6v batteries 2013
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Why 2 6? 2006

maybe 12v is better 2010
12v vs 6v Feb 2010
Sam_Spade
Explorer
Jul 25, 2016
Draggo wrote:
I was buying batteries at different times

That was a BAD plan all along.....if you were using them in parallel and not one at a time.

If you don't want to re-do your cabling, just re-do your plan and start buying high quality batteries in pairs.

6 V in series is a bit better but not a LOT.
coolbreeze01
Explorer
Jul 25, 2016
Typically, batteries used in parallel are replaced in pairs. You don't replace just one battery in a flashlight, do you?
Draggo
Explorer
Jul 25, 2016
Most of the time I am only running one battery at a time because we don't dry camp very often, really only 1 week a year, so I was just replacing the battery when I needed it which is why they were different ages.

I've been thinking about switching over to the 6 volt system for a while but it was always cheaper to buy just one 12 volt rather than 2 6 volt (plus new cases) but I think since both batteries seem to be on their way out now is the time to make the switch.
westend
Explorer
Jul 25, 2016
Mike,
6V batteries will be more durable, generally. They withstand deeper discharges than typical marine hybrid 12V's. It sounds like you are challenged as to charging them back up to full where you are camping. A solar panel may help you out with keeping the batteries charged.

Good luck with the 12 V system.
pianotuna
Nomad III
Jul 25, 2016
For boondocking one week a year it seems silly to have two large capacity jars. It would be better to invest in a modest solar system. Costs for DIY are about $2 per watt for parts and materials.
bill-e
Explorer
Jul 25, 2016
Unfortunately nothing is cheap. I just upgraded to two Trojan T-105RE 6v batteries...cost $340

Add either a generator or solar for recharging and you're looking at a lot more money.

Probably the cheapest way out is to upgrade the batteries and borrow someone's generator for recharging for this once a year trip.
DownTheAvenue
Explorer
Jul 25, 2016
bill-e wrote:

Water pump? even when not pumping if it's turned on there is a current draw.

Not true.
bill-e
Explorer
Jul 25, 2016
DownTheAvenue wrote:
bill-e wrote:

Water pump? even when not pumping if it's turned on there is a current draw.

Not true.
You're right, mea culpa, I was thinking of the water heater.
westend
Explorer
Jul 25, 2016
Yup, batteries are only leased for a usable time period. The trick is to extend that life so that the replacement interval is longer. More capacity = shallower discharge = longer life.

6V batteries bought through Costco, Sam's club, or golf cart distributor are now so cheap that replacing a marine/hybrid 12V makes economic sense.

For operating a 12 V system off-grid, adding solar charging is like peanut butter to jelly. It just works too well to pass up. An owner also gets the advantage of maintaining battery charge while in storage.

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