ajriding wrote:
* just in case someone reading is a very newbie... propane fridges, or 2-way or 3-way fridges heat the gases to make the fridge cool. sounds backwards, but is how it works, so a DC heating element makes the fridge cool, or when on propane, the hot flame makes it cool.
The 3rd way is a heating element that is AC household current, which if you run a generator this will work fine while driving. The DC and AC heating element probably are the same in one and run off either.
The DC and AC elements are not the same element on three-way fridges, because the operating voltages are so widely different. A 300W 120V element has a nominal resistance of 48 ohms; a 300W 12V element has a nominal resistance of 0.48 ohms. To use the same element, the fridge would have to either step down the 120V power to 12V, or step up the 12V to 120V, or convert both to some common voltage, as well as having some circuitry to switch the element between the different supplies. It's simpler and cheaper to just have separate elements. (Very often, too, the 12V element is less powerful than the 120V element to keep the current consumption a little lower.)
