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Topic: Batteries drained overnight 12v fridge? (Read 203 times) previous topic - next topic
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Batteries drained overnight 12v fridge?
the Dometic RM3604 has been working well on all 3 phases, switching between 12v, LP, AC as it should, until today. I noted it was not working on gas as it should, after a long drive yesterday on 12v.

After fiddling a bit, figured out my 12v house system was depleted. Completely. I assume it was not supplying enough power to operate the LP valve, nor the ignition piezo, where I was showing approximately 3.5v. The penny dropped, and I checked my new battery bank, it was about 7v !!!!

Plugged in, waiting to recharge the batteries.

So I now have reduced my Trojans' life. OK, things happen. Still puzzled about what could drain them completely overnight. We have no inverter, we ran one LED for less than a hour. Used no fan, no TV, nothing I can think of. So I suspect the fridge did not automatically cycle to LP when we parked it.

Is this a reasonable assumption? Is it a common problem? Is the solution to simply cycle the fridge manually from now on?
Paul
'92 Mid Bath
Re: Batteries drained overnight 12v fridge?
Reply #1 –
Paul, I have no clue what could have caused it. That's a whole lot of amps that went somewhere. My standard free advise get a battery monitor so you can tell in real time what's going on with your batteries.
Don & Dorothy
Sold our LD in June of 2023

Our boring always non-PC travel blog
Traveling Dorothy
Re: Batteries drained overnight 12v fridge?
Reply #2 –
Paul

Good chance it didn't switch from 12-volt operation to propane correctly, when the ignition was turned off, killing the battery.
From personal experience, my suggestion is run it on propane only, when traveling. One little problem and you have a dead battery in just a few hours.
I understand the appeal of 12-volt operation, our 1983 LD had a 3-way refrigerator. It caused problems when running on 12-volt. It uses a lot of 12-volt power, somewhere around 25-amps.
Newer LDs have not had the 12-volt option for at least twenty  years.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Batteries drained overnight 12v fridge?
Reply #3 –
Thanks Larry, that's how we ran last year. I was overconfident this time! I think we will be taking your advice- LP unless AC.
Paul
'92 Mid Bath
Re: Batteries drained overnight 12v fridge?
Reply #4 –
Don, that is good advice- this year's add on appliance was the Progressive Industries EMS 30. I was all set on  a battery monitor till thinking about all the AC problems I have avoided by luck.
Paul
'92 Mid Bath
Re: Batteries drained overnight 12v fridge?
Reply #5 –
Quote from: paul banbury  - 
So I suspect the fridge did not automatically cycle to LP when we parked it.

Is this a reasonable assumption? Is it a common problem? Is the solution to simply cycle the fridge manually from now on?

This is what I suspect. There is a relay which switches 12V to the fridge when ignition is on, and since it carries a lot of current, the contacts will pit and heat excessively, welding shut. The solution is to either replace the relay or disassemble it and repair the contacts. In our '83, the relay was accessible through the outside access door.

Steve
2004 FL
2013 Honda Fit
Re: Batteries drained overnight 12v fridge?
Reply #6 –
In the end I enjoyed the dread "two malfunction" problem:
First, My brain failed in reading my voltmeter. Idiot.
The other failure was the igniter on the LP system.

I fixed the second, but the first situation is chronic.

Thanks for the help, I'm going back to the little sign we flip over to tell us we have the fridge set on 12 v or LP that hangs on the stove hood.
Paul
'92 Mid Bath