[zroger73]

...inverters are notoriously inefficient.

Actually, even the cheapest inverters are over 90% efficient. The rest is dissipated as heat. "Idle" power is typically only a few watts, if that. If you've got a 100-watt load, no more than about 10 watts is "wasted".

The Ridgeline's headlights alone consume 120 watts of power. Another concern is the type and size of inverter required to start a refrigerator's compressor and prevent it from overheating.

With a refrigerator that consumes 175 watts when running, it probably takes at least 500 watts to start it. The inverter will need to be able to supply this amount of power for a fraction of a second. A 200-watt inverter can't - it would simply turn off. To be safe, you really need about a 1,000-watt inverter. Then, there's the issues of true sine wave vs. approximated sine wave. The latter are cheaper and much more common, but cause motors and other inductive loads to run hot since the output is actually a series of square waves - very poor quality power.

 

[zroger73]

That discussion has been beaten to death on RV and solar living forums all over the internets. Same goes with the "choppy" nature of inverter sine waves & their effect on resistive and inductive loads.

On the topic of AC inversion for running a 3 way fridge, IF the fridge in question is an absorption design (which is by far the most common) the principle behind the system is heat causing ammonia to convert to a gaseous state. That heat can originate from a small flame fueled by propane, or heating coils powered by either AC or DC. When the fridge is running on either electric source, there is no "start up" current spike caused by a compressor motor - therefore 175 Watts (DC) is pretty much a flat current demand whether starting up or running steady state.

Whoops! Having never visited an RV or solar forum, I was speaking purely from personal experience and observations.

I'd really never given much thought to how an RV refrigerator worked. I suppose I was thinking of some sort of "hybrid" design that worked on both propane and had a compressor.