Swap 12v for 120v Fridge Element? UPDATE 2
EDIT--it turned out you can't swap them--they are not the same and it would fry things if you applied 120v to the 12v element ---------------------- UPDATE 25 Jan--12v is cooling down the freezer....
Forum Discussion
road-runner wrote:
On battery 12.8v/9.5a = 121.6w
On converter at 13.6v = 135.2w
On converter at 14.8v = 172.6w
There has to be some measurement error here. If you crank the numbers to get the element resistance, it's lower at 14.8 (1.27 ohms) than at 13.6 (1.37 ohms) That's opposite of reality. Also, for good data, the voltage needs to be measured at the element.
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On paper, going from 12.8 to 13.6 volts should have increased power by about 21% to about 147 watts.
I don't see that happening. The element resistance at 12.8 volts is 1.35 ohms. 12.8 volts/1.35 ohms=9.48 amps*12.8 volts=121.3 watts. Using the same resistance at 13.6 volts: 13.6/1.35=10.1 amps*13.6 volts=137.4 watts, a 13.3% increase.
Don't bother trying to get it to be exact. It does show the increase in watts with higher voltage.
The converter ones were watts as shown on the Kill-A-Watt on the shore power line where mostly it was fridge, the batteries being "full" I had the fridge 12v off, took the watts, turned it on, took the watts, subtract the difference. Used the voltage from battery via Trimetric.
I think there must be some voltage drop. Not much to the fridge PC board, but perhaps more to the element from there. I can't measure DC voltage at the element or at its terminals on the PC board because they are covered with the connections' plastic covers.
I agree the numbers are ropey, but they do still tell the tale.
EDIT--another failure! Got the temp back down in the freezer using gas and went over to 12v. No 12v heater action. Turned fridge off wait two minutes, back on 12v, nothing. So I just left it that way and will see in the morning if it ever did come on.
I don't know how high the freezer temp has to get when on gas so it cycles back on, so I can't say if this is wrong that the 12v did ot come on. (the gas was not burning at that freezer temp, which indicates it was down to as far as it was going to get. The temp settings is at coldest, but it is kind of flakey how that works.)
Anyway the fridge works ok on gas and cycles properly while camping so it gets to stay in place for now.
