Running a 12V fridge? Get a Wireless Thermometer with Min/Max and Alarm...!

e9999

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I have just been testing my truck fridge and solar system, so that reminded me of the following. Mentioning this in case it helps somebody down the line.

Some of you undoubtedly use one already, but for those who don't, an indispensable item to have when using a fridge out there, IMO, is a wireless thermometer. My old one has served me well and I would not go out there without it. Better than a wired one so you don't compromise the lid sealing. A small emitter to be placed in the fridge itself and a receiver that you can keep in the truck. Mine is an antique Radio Shack. Easily 10' range. Some can be had probably for much less than $50 nowadays and are surely better than mine.

Why? Well, the displayed temperature -if any- is from some sensor some place in the wall of the fridge. Not too representative of the temperature inside, likely. And could be way off. So questionable relevance and/or accuracy. The temp may also vary quite a bit depending on the location inside, say bottom vs top. Even more true if you try to set up a ad hoc 2 zones system.

But there are additional benefits:
It should have an alarm, preferably adjustable, if your fridge doesn't. So you can tell if you're getting in trouble without otherwise knowing about it. Say your fridge stops working suddenly. You don't want to find out only the next day after your chicken has gotten warm. Or the fridge can't keep up cuz it's 130F inside.
(But I'd want the means to turn off the alarm. Mine does not allow that and it drives me bonkers cuz it can beep all the time depending on where I set the temp. Been thinking about clipping off the wire to the piezo, it's that bad. But that would defeat some of the purpose, of course.)
Also very important IMO: get one that records the min and max temp so that you can tell what's happening much better and especially after the fact. Say there is an issue. Battery, solar system, whatever. Well you may not know if the bacteria had a big party if you don't record the temps. But with the recording thermometer you can see how hot it got inside to determine how safe the food now is. And you may then not need to throw all the perishables away "just for safety" after all. Also, it allows you to see the swings in temps inside the fridge so you can set the temp better to prevent issues like freezing etc. Also can help with testing. And more.

And can be used for many other tasks around the house or in the truck. I used mine to map my kitchen fridge temps. Could not believe the variations inside... (Brownie points with the Boss...!) I also use it in case it may freeze outside as a warning for pipes etc. Can check temps under the hood, figure out how hot it got in the truck when you left the windows up, etc.

Not to mention that all that is a barrel of fun for us nerdy types... :cheers:



Well worth having, IMHO. Maybe somebody will have some recommendations for a specific current generation one.




(My 2c for the day, worth what you paid for it... :) )
 
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e9999

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Real life example: I set the emitter near the bottom but on basket wires, so not directly touching the bottom. Therefore measuring air temp near the bottom (likely coldest). Fridge empty (so likely more variation in air temp than when full). Fridge set to 34F and showing a swing of 32 to 36 on the display. Ambient temp inside truck about 90-110F.
Wireless thermometer says
Min: 26 and Max: 33F
after many compressor cycles.

Checked it again at night with inside truck temp around 60F and the spread was 26 to 31 or so... Same fridge settings.

Point is that you should take those displayed temps with a grain of salt. But you need something to know for sure.
 
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87warrior

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I've been using this Bluetooth Blue Tempo Disc to monitor the temperature in my cheap fridge. I am not sure if it is possible to set alarms on the app, but it does a nice job of monitoring the temperature remotely.
 
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A similar but slightly cheaper option to the one 87warrior posted is THIS one I currently use in my Dometic CFX3 35. You can setup alarms in the app but just note that the app needs to be active in the background for the alarm to sound on your phone. I've found that it's sometimes 2-5 degrees colder towards the bottom of the full fridge versus the set temperature. Fine for most things but frozen and then thawed veggies is not great so it's helpful to see the true temp and change accordingly.
 

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