dead batteries

Another thing to think about is if you have a climate control switch in the fridge, if it is on that will draw power also.

We use a RV propane fridge as a spare at our cabin,requires 12 volt power. Will kill a single 12v in 4 days ,now have solar charger on it
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Thanks for all the replies, That was only a one time thing, from now on we will be at campgrounds every night or using our generator. when we get home it will be plugged in at the house.

X2
Yes solar panels. The only way to go.

Refrigerator on propane draws about 1 A DC to power the control board.
1 A * 24 hrs/day * 12 days = 288 Ah (ignoring Peukert).
This is not even counting the other parasitic draws.

Time for some solar panels.

No way would they last 12 days with fridge running and all other parasitic drains.

Yes. With it sitting there not used, just the frig and monitors running it will be normal to use about 2 amps of power. So 2 x 24 hours a day = 48 amp HOURS. 48 AH X 12 days = 576 AH. Your two 12 volt batteries are about 90 to 100 AH with the ability to supply about HALF those ah for you to use. So you had 100 ah of batteries to provide this demand. Dead as a door nail and will fail soon if you keep doing that. The batteries need to be kept above 12 volts as a rule of thumb. Get a cheap digital volt meter and mount it where it's easy to see and stay above 12 volts. That may mean plugging in, running the tow vehicle,running a gen or solar. If you then keep doing partial charges the batteries will still fail in less time. If they are wet batteries keep an eye on the water level.

Yes it is very possible, depending also on the SOC of the new batteries.
When new batteries are purchased it is best to fully charge them before putting them into service. It is also a good idea to check the SPG and equalize if needed. These two things will get them started on track for longer service life, along with proper maintenance.
Any time a battery sets at less than full charge it begins to deteriorate, shortening its service life.

When you leave the battery power on for the fridge you also leave it on for the other little parrasitic draws on power such as propane detector and radio as well as the fridge using current for spark every time it lights . so yeah its possible to deplete batteries in 12 days .