Norcold DE/EV 0041 3.6 cf fridge

[Viva]

Ah, true. I'd take back what I said if it were drawing twice the amps but had half the duty cycle.

[boywonder]

Dave: does the link-10 integrate amps?....ie display amp-hr draw? If you have an idea of what your old fridge drew over time, you can compare that to the new one, say over 10 hrs or something.

[daveb]

Originally Posted by Viva

Ah, true. I'd take back what I said if it were drawing twice the amps but had half the duty cycle.

Yep, but it will take some testing like they did on Expedition Portal.

Originally Posted by boywonder

Dave: does the link-10 integrate amps?....ie display amp-hr draw? If you have an idea of what your old fridge drew over time, you can compare that to the new one, say over 10 hrs or something.

Yeah but I never did a test to compare to. To tell the truth I just winged it. I have an idea of normal operation but nothing concrete. Besides that, there are too many other draws that are put into the equation.

[Chance]

Originally Posted by daveb

Instantaneous but I just don't understand why the old model pulls just at 3 amps. I can't say if it cycles less than the old one but would think that would be related to the insulation.

Cycle time is a function of many variables including insulation, other heat load (like opening door), thermal mass, cooling capacity, etc...

If your speculation that the new compressor is larger then I'd expect it to cool down faster and then shut off. Assuming everything else is same as before then it will remain off about the same. Hence it would cycle a little more overall.

[Chance]

Originally Posted by daveb

Yeah I think that is correct and assume the reason they are more efficient in the AC mode is there is a stable voltage supply when converting AC. I could be wrong but on battery power it runs between specific voltages and at a lower the voltage the compressor has to work harder. It would make no sense to invert DC to make an AC compressor work.

...cut......

Dave, I've been meaning to look into these small refrigerators to see how they work. I can't imagine the motor works on both 12 Volt DC and 120 Volt AC, so I assumed they likely use a 120 Volt AC motor and then invert 12 Volt DC when needed. Why do you think this wouldn't make sense?

It's about the only explanation I can see to explain why they would be more efficient on 120 Volt AC.

[Chance]

Originally Posted by daveb

....cut.....

P.S. -- It's hard to take accuracy of technical data seriously when they convert 3.6 cubic feet to 1.1 cubic meters.

[Viva]

Originally Posted by Chance

I can't imagine the motor works on both 12 Volt DC and 120 Volt AC, so I assumed they likely use a 120 Volt AC motor and then invert 12 Volt DC when needed. Why do you think this wouldn't make sense?

One reason I could think of is that with many of these (at least the marine ones I'm familiar with) have a base model that is 12-volt only, and then an optional version of the same model that can also run on 110 (along with 12-volt). So that makes it seem like 12-volt operation is the base, and the 110 is some sort of add on feature.

[daveb]

Chance I think you read me wrong. Maybe I should have worded it battery reserves and shore power. It takes power to invert so being they are made for 12 volt operation while trying to be as stingy as possible to use a minimal amount of battery reserves, it would seem taking 12vDC then wasting power to invert to AC would be contrary to the goal. My point about being more efficient on AC is that shore power is stable while DC battery power isn't. So the lower the battery reserves go the harder the compressor has to work pulling more amps. It's why many have a shutdown threshold on DC voltages.
Many are 12vDC only and the vehicle or vessel is best off to have a converter so you're not over charging and cycling the battery system while on shore power. As I posted earlier, it's the reason I went with the Norcold in the first place besides price. I would tend to agree with Viva... the 110vAC is a convenience. If I find the Norcold a power hog, I'll probably go with a Isotherm and add a converter and chalk it up as a costly mistake. Again, I'm not one to turn my fridge off very often so as it sits on the driveway I'd need a converter which is just more money.

But I think it's wrong for Norcold to not post the correct specs. And if indeed it is cycling less than the older version, why isn't Norcold tooting their horn about having a more efficient unit. I'm told they all pull more now, even the smaller unit.

It would take a side by side comparison like they did with the portable units at Expedition Portal. I never did take the time to do an amp-hour check in specific temps. In the times I've been out, it does not run nearly as long as the old model when it cycles on, but I never did time the cycle lengths...it just seems shorter. Maybe wishful thinking