pianotuna wrote:
Since the power factor on AC voltage is 1 for resistance heating devices, going from 120 volts to 110 volts represents a power loss of only 27 watts. My own fridge works well down to 100 volts (a loss of 54 watts, or about 1/2 the heat of a candle).
In your example, you'd be down to 84% of the rated output of the element in the fridge at 110 volts so if you have a 300 watt element, you've lost 48 watts and at 100 volts, 93 watts. Not sure about Dometic but Norcold specifies a min. of 108 volts.
The output of any resistive device, like a heating element, varies as the square of the voltage. (Ohms law.) If the voltage happened to be down to 104 volts, the point of a PI EMS cutting out, it's lost 25% of it's normal output. At 100 volts, it would have lost 31% of it's normal output. That amount of drop is significant and I would guess that the cooling output of the fridges drops faster than the corresponding output drop in the heating element. Try holding a 25, 60 or a 90 watt incandescent light bulb and see how long you can hold on!
I believe the elements in RV fridges are all rated for 120 volts but as many of us know, CG voltage can get pretty low sometimes. That's where an autoformer can really help. Same with toasters, coffee pots, hair dryers and the like.
