A couple thoughts--
1- the on the wall battery indicator is woefully in-accurate. You really need
a digital volt meter. Keep in mind when lead acid batteries read 12v they are
pretty low on charge. We're talking a few 10ths of a volt between full and low.
2- I always recommend a little testing to try and find the culprit that may
be draining your batteries. If you take a digital multi-meter with amps scale
you can pull the 12v fuses one at a time. Place the meter leads across the
empty fuse holder and read amps. Take notes. You may be surprised to find
different fuses do have a load on them even tho you thought everything
3- There has been some discussion here about some dometic refrigerators
having a 12v heater strip between the freezer and fresh food door. It's supposed to keep that little strip of metal from gathering condensation. The problem is the heater is 12v and it can drain your batteries in a day.
Some have a switch to shut off the heater and some don't. Check your fridge literature and do the ammeter test as mentioned above.
Several of us here have added a little digital voltage display such as this one- New Brand DC 0 30V Blue LED 3 Digital Display Voltage Voltmeter Panel Erus | eBay
It's sold by ebay and direct shipped from China. Mine arrived in less than 3 weeks. I added a push button switch so it's not on unless I want to see the voltage.