Updated: Jul 17, 2020
High Efficiency Cooler doesn’t ever need ice!
I have been researching high efficiency Danfoss compressor refrigerators for a couple of years, hoping to replace my gas fridge in my RV. Refrigerators are one of the highest energy consumers in your RV, and when you are totally off grid like I am, you need to be aware of where your energy is going. I considered a regular household refrigerator, since I have a huge solar and lithium battery bank, but when I did my research I discovered some interesting facts.
1) A typical household fridge uses around 1.5KWH (kilowatt-hours) per day. An 18cf Energy Star fridge uses around 1.1KWH per day.
2) An 8cf RV gas fridge, running on 120V electric, uses about 3KWH per day! That is 2-3 times more than a household fridge. No wonder everyone runs them on gas instead of electric.
3) The old fashioned thermoelectric 12V fridges (Koolatron) uses 60W per hour, but it runs continuously so it takes 1.5KWH per day! It can only cool about 30-40F below ambient. They are cheap, but I hated mine. It was an energy hog and didn’t cool very well.
3) A typical 10cf 12V Danfoss compressor fridge runs on about 0.6KWH per day. That is twice as efficient as a household fridge and 5 times more efficient than an RV gas fridge!
So last year when I met Daniel from indel B (Kentucky) at America’s Largest RV Show in Hershey, PA, I jumped at the chance to pick his brain on Danfoss compressor fridges. The first thing he taught me was that Secop has bought out the Danfoss technology, so they are now 12V Secop compressor fridges. indel B, an Italian company, has been designing and manufacturing truck, car, and portable refrigerators for many years, and has recently expanded in the RV, Jeep, and off grid markets in America. They use the super high efficiency Danfoss (now Secop) compressors, which are lightweight and very low power.
Daniel knows a lot about high efficiency fridges but had never tried to run one from a solar system. So we decided to combine forces and do some detailed, real life testing. I have designed and manufactured various solar systems for years, and so came
I loaded the TB-13 with 12 cans of room temperature beer and connected a Thornwave Bluetooth battery monitor to measure the total kwh used.
For solar power, I connected a 160W portable solar panel through a 50’ extension cable. This panel should have enough power to the run the fridge while the sun is shining, and enough power left over to keep the battery fully charged. Since my RV is currently parked in the shade, I mounted the solar panel on the front of the RV temporarily, using the skirting snaps that were already there. The solar panel will only get sun from about 3 in the afternoon until about 6-7 PM, which is not ideal, but does simulate how a portable panel is often used in the real world. Plus it was easy and I’m lazy.
I turned it on at 1PM on Wednesday, and started recording power and temperature data. The TB-13 draws a measly 2.6 amps from the battery and solar panel.
For the first 3.5 hours, the compressor ran continuously, then started to cycle to maintain the nice cold beer temperature. I had accidentally set the temperature for 32F, so I had to adjust it up a little to keep the beer from freezing. Total power consumption for the 3.5 hours it took to cool down the beer was a meager 9.1AH or 115WH. Of course, it would make more sense to put cold beer in the fridge with the optional wall power supply first.
You can see that it took a few hours for the TB-13 fridge to get the beer down to acceptable temperature, actually, a bit too cold. I adjusted the thermostat up a bit. 12 cans of beer are quite a large thermal load, but the TB-13 seemed to handle it with ease. The sound of the Danfoss (Secop) compressor is very quiet, so quiet that you would barely notice it if it were next to your bed at night.
I ran the cooler for several days to get an average daily power draw. The average was about 400W per day. The flexible solar panel was making about 600W per day, so easily kept the battery fully charged every day. Of course, the number of the beers in the cooler was steadily decreasing as the days passed, but still a valid test.
I was so impressed with the performance of the TB-13 cooler, that I plan to recreate this experiment on some of the larger models of coolers and fridges from indel B. You can see some of the other fridge models, and our other cool solar stuff at https://www.leisuresolar.com. As always, we are available to chat via phone or email for all of your RV, cabin, and portable power needs.