By Mike Sokol
Dear Readers,
After a few false starts and stops I’ve finally finished my first series of tests on an 8-cubic-foot Vitrifrigo DP2600 Danfoss compressor refrigerator powered by a single 100 amp-hour Ion-Ready Lithium battery from Briter Products. And the run times using the refrigerator’s built-in 12-volt connection are quite a bit longer than using a 100 amp-hour battery to power a 1,000-watt inverter which powers a residential refrigerator with a conventional compressor. Here are the basic numbers.
Briter Products 100 amp-hour Ion-Ready Battery discharged to 5% of capacity
Marinco 1,000 watt pure-sine inverter
Vitrifrigo 8 cu.ft. refrigerator using its 120-volt AC supply
Average Room Temp 70 degrees F
Refrigerator run time was 23 hours
Briter Products 100 amp-hour Ion-Ready Battery discharged to 4% of capacity
Galaxy 250 watt pure-sine inverter
Vitrifrigo 8 cu.ft. refrigerator using its 120-volt AC supply
Average Room Temp 70 degrees F
Refrigerator run time was 29 hours
Briter Products 100 amp-hour Ion-Ready Battery discharged to 16% of capacity
Vitrifrigo 8 cu.ft refrigerator using its 12-volt DC input
Average Room Temp 70 degrees F
Refrigerator run time was 38 hours
My basic compressor 16-cubic-foot refrigerator/freezer in the basement eats up around 100 watt-hours of power per hour, so that’s around 2.4 kW-hours per day. That suggests that even with an inverter that had 100% efficiency (which doesn’t exist, by the way) you might get 10 to 12 hours of running time for this refrigerator from this same Lithium battery/inverter setup which can provide about 1,200 watt-hours (1.2 kW-hours) of storage capacity. Of course, your mileage will vary depending on the size and efficiency of your residential refrigerator.
Of course, as you can see from the chart, hooking up the Vitrifrigo refrigerator’s Danfoss compressor directly to your 12-volt RV battery will be the most efficient way to run things since you don’t have the 1,000 watt inverter’s overhead of 15 watts just to run the fan, or the 250 watt inverter’s 10 watts of idle power it wastes. And, of course, you have to also factor in the 5% or so of additional power loss due to inverter inefficiencies.
The bottom line appears to be that a Vitrifrigo DP2600 8-cubic-foot Danfoss compressor refrigerator uses around 1/3 of the energy of a conventional 120-volt AC, 16 cu.ft. conventional compressor refrigerator. Interpolating the data a bit for the difference of the surface areas between the two refrigerator’s cubic foot capacities, the Vitrifrigo Danfoss compressor refrigerator uses less than 1/2 the power of a similar-sized conventional compressor refrigerator.
This suggests that the Danfoss compressor refrigerator makes boondocking without a generator using a single 100 amp-hour Lithium Battery such as the Briter Products Ion-Ready a possibility, even with just 200 to 300 watts of solar panels. More on this later after I set up my solar panels next month for more testing, but it looks very promising.
Let’s play safe out there….
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
##RVT946
We are expecting delivery of a Coach House 271 in April. Making frig decision 8 cu. Dometic 3 way or Norcold 2 way. The norcold reviews are as bad as I have ever seen on a product. Think we are going with this Vitrifrigo if the builder agrees. We will have 2 lithium batteries and 380 w of solar.
Gotta admit that the test kinda confused me when you tested an 8 cf against a 16 cf refrigerator…
I would suspect that with all things equal, the 16 cf would be 16 hours total run time per day against the 10-12 hours of the 8 cf unit per day. But alias, not all things are going to be equal.
It would be great if you can compare the 16 cf against the 16 cf. Is that possible? I like the potential though.
With the Vitrifrigo DP2600, are all components (fan, controls, compressor) 12V? You seem to suggest that the inverter could be bypassed.
With solar panels, it sounds like one could run the refrigerator during the day off that alone given enough capacity. We have 1300 Watts available per hour. It sounds like that at night, it would take just 1 (100A) battery to run the refrigerator all night. The other 3 (100A) lithium’s could take care of everything else with reserve to spare.
But what about the price comparison of the Vitrifrigo DP2600 against a Norcold or Dometic?
BTW…Keep up the great work you do. It’s much appreciated.
Checked out the Vitrifrigo website. Doesn’t look like they offer a 16 cf unit. Hmmm…
http://www.vitrifrigo.com/us/us/#
Given enough room, maybe two 8 cf tall units? Seems like a lot of work…
Sent comment on the Vitrifrigo website suggesting a direct replacement for the 16 CF Dometic and Norcold brands. Maybe they will respond? Mentioned RVTravel.com as well.
Hummm… Turns out it may be 12 CF for a Norcold 1201IM…Still, it seems that they only make the 10 CF. 12 is hard enough…
The Vitrifrigo line can run on 12/24, 110/220 50 or 60 Hz. We are competitive with those other brands price wise with much higher efficiency, and materials of construction.
After reading all this I’m so happy w my propane. refer and furnace.
We are exceptionally happy with this choice compared to a residential refrigerator thus far. We can boondock anywhere. 6 years of travel with no problems.
Just a note. The battery is sold by Briter products not Briter technology. Also I am not sure that would be a good battery for most RV’s. Based on their specs it does not have a low temp charge cutoff. My understanding is if you try to charge a lithium battery below its low temp range (typically freezing) you will destroy the very pricey battery.
I’ll confirm with Briter engineering, but as far as I know it does have a low temp charge cutoff. Note that I’ve asked Trojan and Battle Born for samples of their batteries but they refused. Since I have zero budget for these tests I can’t afford to buy batteries to experiment with.
Hello Tony,
This is Avanti from Briter Products, the company behind the Ion-Ready battery that was used in the test with Vitrifrigo.
Our Lithium-Ion battery was *specifically* designed for RVs! You are right, Lithium-Ion batteries do require a low temperature cutoff. Under the specifications tab on the battery’s product page – detailed specifications are listed.
https://www.briterproducts.com/product-page/ion-ready-t
On this page is the operating temperatures for the Ion-Ready battery:
Charge -4°～140°F (-20°～60°C)
Discharge 32°～104°F (0°～40°C)
Note these temperatures are not ambient temperatures – but the temperature of the core of the battery where the sensors are.
We are so glad that understanding of this highly rechargeable technology is increasing. Thank you for making this very important point and if you have any other questions – please feel free to call us at 574-703-1873.
Thank you,
Avanti
We have the Battle-Borne ($1000 each). Great battery. I would think that manufacturers would support you given the advertisement that they could get. I think they are missing the bigger picture. too bad.
Keep up the great work though!
I see that his basement refer uses a conventional compressor maybe the one Mike took out of the kitchen 20 years ago when they got a new one! Modern day refers seem to use a lot-lot less energy. It has something to do with the use of inverter linear compressor. Theres a lot more that I don’t know but would like to know. I have a residential refrigerator & I get totally different readings when I use my inverter on my 2017 Forest River 34QS. I had my doubts as to what my Magnum inverter display was saying , like the draw was 7Amps! So I bought a clamp on meter & read the draw from the battery to the 2K magnum pure sine wave inverter & it said 12 amps & that was the total draw for whatever was running. According to the refer label it drew 6 amps @115 volts, well thats 72 amps @12 vdc! Can anyone tell me about this, or am I all wrong?
Snoopy
I used an external DC clamp meter on the DC battery side and AC clamp meter on the 120-volt AC side to confirm amperage draw. I also timed how long it took to get the battery power down to the listed percentages of charge. So I’m confident that the data that I gathered for the Vitrifrigo/Danfoss unit. And yes this was a 20 year old conventional refrigerator in the basement. However, I discussed this with a few modern refrigerator manufacturers who said my residential numbers were reasonable, along with some of my readers who complain their battery dies after 8 hours of running their residential refrigerator. Again, this is a preliminary study to test proof of concept.
Your mismatched readings are likely due to not using true RMS meters for measurements. A standard AC meter (both for current and voltage) simply reads the peak voltage or current, then divides it by 1.416 (the square root of 2 which is what RMS or Root Mean Square is all about) to come up with a guess of the RMS voltage or current. However, distorted waveforms don’t convert their peak values to RMS that way.
How does the efficiency compare when you use a cu. foot per KWH comparison? For equivalent volume, it uses 33% less power. That’s nothing to sneeze at, but how much renovation and inconvenience is that going to offset?
You need to compare surface area, not simply volume when comparing refrigerators. That’s because as you increase the volume of a rectangular cube, the surface area doesn’t increase proportionally. Since most of the heat transfer through the insulation is factor of surface area (as well as Delta T), doubling the cubic capacity of a refrigerator won’t double the energy usage.
This initial study is about new RV builds using 12 volt DC compressor refrigerators instead of residential refrigerators with an inverter. It’s not intended as a detailed study on retrofitting Danfoss compressor refrigerators to replace existing residential refrigerators in RVs.
I can’t find a chart!
Hi Harry, its the 3 comparisons of the Briter Technology 100 amp-hour Ion-Ready Battery in different usages! Hope this helps, Ya I was looking for a chart that Mike would usually use also!
Snoopy
First line, sixth paragraph, he says…..
From the chart you can see
I don’t see any charts!
Sorry, Harry. It probably would have been better to refer to the information as lists, since there were no lines or graphics which would have made the information presented an actual “chart.” —Diane
Yes, that’s correct. I have pages of charts I used to create a short list of run times since most readers wouldn’t be able to easily interpret a lab chart.
I don’t publish my lab charts to the general public as they’re too complex to interpret. I only send them to my colleagues for peer review and discussion. However, once I get my new test lab built I should be able to automate the test procedures so I can easily create performance graphs that would be simple for the public to interpret.
Factoring in the cubic foot capacity of the two fridges, this isn’t nearly as impressive as it sounds, Mike. I don’t know about you, but I’m certain MY Co-Pilot isn’t going to live with an 8 CF fridge, no matter how much easier it makes boondocking. We’ll stick with our two-door Dometic, thanks anyway. At around 13 CF, It’s already barely big enough for our needs.
People’s needs vary so much. We do quite well with a 12V, 4 cu foot Isotherm refer/freezer. We also are 100% solar. Our footprint is small by choice, so are our needs. We don’t have a TV either, or silly light strings, etc… To each his own.
Dometic is now sending me their 10 cubic foot RV refrigerator with a Danfoss “style” compressor for comparison. And Vitrifrigo currently manufactures a 16 cubic foot version that uses a pair of Danfoss 12 volt DC compressors. What I need is a grant to create a real side-by-side study because these tests take a lot of time and resources, and I have zero budget for any of this. But the preliminary study looks promising.
We have a size bigger that you might like
http://www.vitrifrigo.com/us/us/dw360ixd4-efv-upper-refrigerator-compartment-and-lower-freezer-refrigerator-compartment
You didn’t mention running the 12 volt fridge on 120V with the inverter is a double conversion. 12 volt battery to 120V inverter to fridge internal converter to 12 volt compressor.
Yes, I’m aware of that that, which is why I did that as the initial test and you can see that reflected in the numbers.