The other problem is that I don't think there's any kind of power converter in a Dometic RM211... these units run on the absorption principle, which is driven by heat. The
propane, 12V DC, and 120V AC are all just used to provide heat. In a normal 3-way
refrigerator, there is no converter to change one voltage of electricity to the other; instead, there are separate 12V and 120V heating elements.
To make AC power for the Home Depot
refrigerator, you need an inverter. Those are cheap and readily available... but the refrigerator's power demand, compounded by inverter inefficiency, cause the problem Peter mentioned when running from a
battery. On the other hand, running this type of
refrigerator on AC power at a serviced campsite and via an inverter while hitched to a running tow vehicle's 12V power
does seem like a practical option.