how long does the fridge stay cool?

[pianotuna]

Hi,

I was forced to park in a manner where I thought it prudent to turn the fridge off.

I've often seen folks claim the fridge is cool after many hours. This appears to be apocryphal.

The fridge:

Dometic Royale Tri-Fuel Fridge (6 cu. ft.)

The conditions:

I parked with the fridge on the north side so it was not in direct sunlight. Ambient temperature was 22 C (71.6 f). There was mixed cloud, and it was 1 p.m.

Interior of the RV was 22 c (71.6 f)

Interior of the fridge was 2.7 c (37 f), measured on the top shelf of the door.

After 2 hours the interior of the fridge had risen to 6.4 c (43.5 f)

The drain tube is properly set up with a dip in it to prevent air infiltration.

As I knew I would have power later, when I restarted the fridge I did it on 120 volts via the inverter. Input from alternator and solar to the fridge were about 25 amps. I drove for about 2 hours and the batteries were quite happy to start recharging at 24 amps once I had shore power. While the fridge was playing catch up duty cycle appear to be 100%.

The fridge was not opened and the interior was still at 4.5 c (40.1 f) after the two hours of run time. It is equipped with a dual interior fan, and dual "chimney" fans that sucks air over the exterior coils. The unit has the ARP control installed. (I love having that btw--no more driving in endless circles in parking lots to get perfectly level!)

My conclusion is that the fridge can be shut down for only one hour from a safe food storage point of view.

[pianotuna]

Hi ksg,

Where do you keep the sensor (inside the fridge)? What make and model of fridge do you have?

Yes thermal mass makes a difference.

I'm tempted to try this again but with the drain plugged from inside the fridge.

ksg5000 wrote:
My experience is contrary to yours - I keep an external remote thermometer in my fridge and I can turn the power off and it will maintain temp for many hours and go for at least 8 hours B4 temp gets high enough to raise any concerns. Maybe one or both of us have lousy temp gauges? I suspect the amt of cold food/thermal mass in a fridge has a significant impact.

[Almot]

Don, I think what you see is not uncommon, though yours seems to be worse than average.

Rarely turn mine off after I've settled down on the camp, so don't keep a wireless thermometer. So, without measuring accurately (or at all) - temperature rises by 2C (4F) or more in less than 4 hours at temps in upper 20s (82-84F). I know this because it's cycling 100% for some time after that (for at least one hour), and by how much "pop" I get when opening a soda bottle. 6-something cu.ft Norcold.

Opening the door at 84F is a killer, even when it's running. I think the problem is that fridges under 7 cu.ft are very shallow inside, front to back. Have never observed anything even close on deeper compressor fridges.

[ksg5000]

My experience is contrary to yours - I keep an external remote thermometer in my fridge and I can turn the power off and it will maintain temp for many hours and go for at least 8 hours B4 temp gets high enough to raise any concerns. Maybe one or both of us have lousy temp gauges? I suspect the amt of cold food/thermal mass in a fridge has a significant impact.

[pianotuna]

"The fridge was not opened"

Since the recommended number for food storage is a minimum of 4.5 c (40 f) and the interior was above that number for at least 2 hours (and more probably 3), it is an issue.

The freezer, on the other hand, has no "direct connection to the outside world" via the drain tube, so it will not rise in temperature nearly so quickly.

Kayteg1 wrote:
Did you open the door to measure the temperature, or do you have one of those outside thermometer?
3.7C raise in 2 hr is not bad IMHO. Bare in mind that with fridge off it is the food who is the source of cold, meaning the internal walls will be warmer than the food itself.
I would more worry about freezer side as defrost food should not be frozen again.

[K_Charles]

That may be why many people, me included, never shut off the fridge.

[Kayteg1]

Did you open the door to measure the temperature, or do you have one of those outside thermometer?
3.7C raise in 2 hr is not bad IMHO. Bare in mind that with fridge off it is the food who is the source of cold, meaning the internal walls will be warmer than the food itself.
I would more worry about freezer side as defrost food should not be frozen again.