Different models and sizes of fridges could dictate the power requirements. Our 2310H fridge draws 15 amps on 12 volts.
Correct! And that's just 180 Watts! It's very little POWER, really but when the voltage (electrical pressure) is low, the Amperage (electrical volume) has to go up and that high Amperage needs a fat wire (big pipe) or it can't get though. (I know you know this Rich, I'm just trying to explain things to some that may not.)
Now, if the voltage was 120, the needed Amperage would be 1.5A. You can pass 1.5A through a very small wire.
So, this is why the inverter may be a good solution, if the battery charging circuit from the tow vehicle to the trailer is designed with wire that isn't a heavy enough gauge.
And, 180 Watts may be a low power requirement, but 15A is a heavy draw on a battery! In four hours, that pull totals 60A, which kills most wet cell batteries. However, if you can supply the power from the tow vehicle's alternator, either through the charging circuit or through an inverter that's powered from the tow vehicle, you can run the refrigerator indefinitely, as long as the engine is running. But, if you adopt the inverter solution, you need to get its input from the tow vehicle, not the trailer, or you will be increasing the draw on the trailer's battery.
- Jack