Measuring and Recording Refrigerator Temperatures

[TucsonJim]

I'm currently doing some research for GDRV on 12V DC compressor refrigerators. As part of my study, I'll be recording temperatures over time in order to evaluate cooling times and efficiency. In the process of doing so, I came across a tool that RV owners might want to have to check out their own refrigerators. It is a data logging device you can place in the refrigerator to record temperature and/or humidity over time. Here is a link to the one I purchased on Amazon.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

For $33, it gives you excellent data that you can use for your own purposes or if to see if you have an issue with your refrigerator. They even offer a lower priced one that does not record humidity. I ran an initial test on my 8 cubic foot Norcold a**orption refrigerator. You can see the graph it generates in the attached photo.

Jim


Note: If you haven't read Jim's study on RV refrigerators and food safety, check out this thread: https://gdrvowners.com/forum/operati...d-temperatures -Moderator Howard

[howson]

I'm currently doing some research for GDRV on 12V DC compressor refrigerators. As part of my study, I'll be recording temperatures over time in order to evaluate cooling times and efficiency. In the process of doing so, I came across a tool that RV owners might want to have to check out their own refrigerators. It is a data logging device you can place in the refrigerator to record temperature and/or humidity over time. Here is a link to the one I purchased on Amazon.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

For $33, it gives you excellent data that you can use for your own purposes or if to see if you have an issue with your refrigerator. They even offer a lower priced one that does not record humidity. I ran an initial test on my 8 cubic foot Norcold absorption refrigerator. You can see the graph it generates in the attached photo.

Jim

That is freaking cool (pun intended?)! You know I can't resist a gadget...dang it, Jim, I'm gonna have to get one. (Happy Thanksgiving to you, Ginnie, and the pups!)

[Yattr]

Very cool device and informative graph. Already in my cart! Will test both my 4 door Norcold next month and my 4 door Dometic this coming summer. THANKS!

[Mark&Colleen]

Thanks for this Jim. As per my other posts I am having cooling issues with my refer so this will be a nice tool to track what is going on inside.

Mark

[howson]

For $33, it gives you excellent data that you can use for your own purposes or if to see if you have an issue with your refrigerator.

Got mine today, Jim, and I'm testing it in my home's residential Samsung. I had the temp parameter set to C instead of F so not as easy to read (except for a well-known Canadian moderator).

Of interest, 7.5C translates to ~45F. According to what I can find on the web, the ideal temp for a refrigerator is 35F to 38F. I'm running another test overnight to verify. If it's still 45F I'm going to turn down the 'frig a notch and test again.

Fairly simple to use.

Interesting to see how sensitive the device is--you can tell by the humidity every time the door was opened this evening. (The device is on a door shelf.)

[TucsonJim]

Got mine today, Jim, and I'm testing it in my home's residential Samsung. I had the temp parameter set to C instead of F so not as easy to read (except for a well-known Canadian moderator).

Of interest, 7.5C translates to ~45F. According to what I can find on the web, the ideal temp for a refrigerator is 35F to 38F. I'm running another test overnight to verify. If it's still 45F I'm going to turn down the 'frig a notch and test again.

Fairly simple to use.

Interesting to see how sensitive the device is--you can tell by the humidity every time the door was opened this evening. (The device is on a door shelf.)

What a great tool for the price. I opened my door one time and had the big humidity spike when I did. If you look at my study on food safety, the maximum safe temperature for a refrigerator is 40°F.

Jim

[Cate&Rob]

I had the temp parameter set to C instead of F so not as easy to read (except for a well-known Canadian moderator).

The whole world thinks in C (except the US and the Bahamas) . . . I happen to know that Mark Mark&Colleen will be thinking in C as well .
Great data! We will soon know more about the performance parameters of these fridges than the manufacturers do.

Rob

[howson]

What a great tool for the price. I opened my door one time and had the big humidity spike when I did. If you look at my study on food safety, the maximum safe temperature for a refrigerator is 40°F.

Jim

Jim,
I confirmed (according to the Elitech tool) that my home's Samsung temp is 43.7F. The sensor was on a shelf in the door with the fridge's temp setting at 38F. (So there's a 5 degree difference between the setting and actual temperature.)

I lowered the Samsung's temp setting to 36F and put the sensor in the back on the bottom shelf. It will be interesting to see the results later today.

Given that the refrigerator door stays closed, do you expect any difference in temperature inside the frig front-to-back or side-to-side? Now that I've moved the sensor to the back of lowest section, do you expect the temperature to change more than 2 degrees? (The temp should be lower because I lowered the setting 2 degrees.)

I guess what I'm asking is this: Is there a methodology you've established for testing that we can follow so our results can be compared?

-Howard

[Mark&Colleen]

I find myself getting very used to F living in Florida as that is what we all grew up with before we switched to C. Ha!

This thermometer is a great tool for trouble shooting for sure! I should get mine early next week. Very interested in the results I'll get. BTW, fridge is performing very well lately as we haven't had much humidity lately.

[TucsonJim]

Jim,
I confirmed (according to the Elitech tool) that my home's Samsung temp is 43.7F. The sensor was on a shelf in the door with the fridge's temp setting at 38F. (So there's a 5 degree difference between the setting and actual temperature.)

I lowered the Samsung's temp setting to 36F and put the sensor in the back on the bottom shelf. It will be interesting to see the results later today.

Given that the refrigerator door stays closed, do you expect any difference in temperature inside the frig front-to-back or side-to-side? Now that I've moved the sensor to the back of lowest section, do you expect the temperature to change more than 2 degrees? (The temp should be lower because I lowered the setting 2 degrees.)

I guess what I'm asking is this: Is there a methodology you've established for testing that we can follow so our results can be compared?

-Howard

Howard - I just received word that the 12V reefer should be arriving this week. For my basic experiments, I'm placing the thermometer in the center of the refrigerator cavity. I have four more temperature recorders on order. One of the experiments I'll perform is recording the refrigerator temperature at various locations at the same time. This should tell me if there are hot spots or not.

Jim

[Yattr]

Purchased a temp only unit. Was using a setting of 2 but noticed it wasn’t adequate to keep refrigerator temp below 40. Here are the results for a setting of 3.

As stated somewhere the top left freezer compartment is the coldest.

The original control board and thermistor have been replaced recently. This unit is now functioning better than when new!

[TucsonJim]

Purchased a temp only unit. Was using a setting of 2 but noticed it wasn’t adequate to keep refrigerator temp below 40. Here are the results for a setting of 3.

As stated somewhere the top left freezer compartment is the coldest.

The original control board and thermistor have been replaced recently. This unit is now functioning better than when new!

Wow - Those results really demonstrate a few things.

1. It would be good to have a circulating fan running to even out the temperatures.
2. You can certainly see the small spikes of when the unit went into cooling mode.
3. I think I can tell when you opened the door.

[TucsonJim]

Here is a graph I generated with the new DC refrigerator. Temperatures are from the refrigerator, freezer, RV interior, RV exterior and compressor.

[howson]

Here is a graph I generated with the new DC refrigerator. Temperatures are from the refrigerator, freezer, RV interior, RV exterior and compressor.

When the graph states the refrigerator consumed 63amperes, is that the same as stating it consumed 63aH? I'm so used to the aH figures (because of battery ratings) that I'm easily confused...

[TucsonJim]

When the graph states the refrigerator consumed 63amperes, is that the same as stating it consumed 63aH? I'm so used to the aH figures (because of battery ratings) that I'm easily confused...

That is an excellent question Howard. An amp hour is how many amps are used in a one hour period. For example, If I draw 3 amps in an hour, that is 3 amp hours. If I draw 30 amps in 10 hours, it's still 3 amps/hour (average) In this case, the refrigerator consumed 63 amperes in 24 hours. 63 Amps ÷ 24 hours = 2.625 amps per hour (average).

I will say that the following day, I turned the refrigerator up to max, and set the fireplace to 90°F for 24 hours. This is a worst case condition and the refrigerator consumed 92 amps, or 3.8 amps/hour (average).

Jim