bought a 120v cube fridge

[jonsun]

http://www.truckfridge.com/tf65/

Heres a great example. The trucker fridge uses 60w with average consumption of 24w / hr. Meaning it cycles nearly 50%....any efficiency gains over the 120v in the 60w compressor has been lost at the longer cycle time.

86w @30% duty cycle 25.8w / hr vs 24w - no free energy

what I think you missunderstood is your "x3 as much", meaning yours is using 2.4A, is your average consumption. your fridge obviously doesn't have a 30w compressor. But his duty cycle of ~30% means .75A x 3 - 2.25A average consumption. The same as yours.

Hope that helps

 

[John61CT]

No, we're saying they use 3x the juice taking cycling into account.

In moderate conditions, often as low as 7 minutes per hour.

And just twist the knob it's a freezer, then of course cycles more.

Portability is great too, move it from home to van to truck to shack, no problems.

Again, if you really can't afford the right gear fine make do for now, but start saving so when it breaks, or if you see a great CL deal you're ready to go.

 

[jonsun]

so your unit is running a 30w compressor and running a 30% duty cycle? That's 1/3 the trucker fridge! clearly not all 12v fridges are equal. care to post the exact specs? The 12v fridges seem pretty secretive with their consumption data.

I'll be sure to start saving, if I go through 1 a year by 2027 I will have broke even against a real one!

maybe I could go to 2030 with this on for $50? It only uses .8A
https://www.walmart.com/ip/GALANZ-1...75035&wl11=online&wl12=40685158&wl13=&veh=sem

 

[highdesertranger]

my Engels run between 20-30% duty cycle depending on ambient temp and the dial setting. actually if it's real cold out and I turn the setting way down the duty cycle is under 10%. also if I use one as a freezer I will turn it up to the max for 12-24 hours then I can turn it way down to were the duty cycle is close to 10% and the food will stay mostly frozen for over 2 weeks. if I keep the duty cycle at about 20% the food will stay rock hard indifferently. the Engels use 2.5 amps @ 100% duty cycle at 12v. highdesertranger

 

[John61CT]

> maybe I could go to 2030 with this on for $50? It only uses .8A

at 115V AC, right?

Which means 7A at ~12V

Again, about triple the consumption, with less usable volume.

I think this dead horse's been beaten enough

Again, do what you like. . .

 

[jimindenver]

I guess I don't get all the grief. It doesn't seem like a massive power hog. The fear of it falling apart instantly seems to have been put to bed by others using mini fridges or even RV manufactures installing residential units. So what if someone would rather spend $100 on a fridge and the other $700 to power it instead of $100 solar system to power a $700 fridge. We should be celebrating the fact that there may be a less expensive way to do it for those that can't afford a Engel.

 

[John61CT]

Completely agree.

Just was a bit tough getting the efficiency part across in this case.

 

[jonsun]

Well we want to make sure we arent misleading anyone by being plain wrong. My tests are unusually cool for this time of year for example. I just want to get to the bottom of it and do it at the lowest possible overhead....same with my stances on PSW and MPPT.

 

[jonsun]

> maybe I could go to 2030 with this on for $50? It only uses .8A

at 115V AC, right?

Which means 7A at ~12V

Again, about triple the consumption, with less usable volume.

I think this dead horse's been beaten enough

Again, do what you like. . .

Again 20a a day is equal, not triple. Post a pic of your compressors actual wattage, not its average hourly consumption because duty cycle matters bigly.

And thats at 50 quarts with a freezer. So better and more space than most 12v units. At fractions the price.

I think you want to justify your expensive purchase more than anything.

 

[jimindenver]

It does seem to be that the owners of the expensive must come to the rescue of their brand anytime some one varies from what is seen as the best path in their eyes. Efficiency doesn't have to mean just one thing. It could be how much power to capacity. It could be cost or how well the unit is insulated, each of us finds our own balance. Personally I could replace my Engel with a small chest freezer and never notice the difference in consumption but the extra capacity and much thicker insulation would be appreciated. I have a stadium blanket draped over my Engel to add some insulation, stick your hand under it, feel the lid and you can tell how thin the insulation is on the Engels. I can add insulation but dang, you would think they would have on a unit that cost this much.

So while we all think what we use is best, we have to remember that it is what is best for us and someone else may have a different balance to achieve.

 

[UptownSport]

maybe I could go to 2030 with this on for $50? It only uses .8A
https://www.walmart.com/ip/GALANZ-1...75035&wl11=online&wl12=40685158&wl13=&veh=sem

Thanks!
bought a haier (sp?) yesterday, and immediately returned it- it was 1.45A. Where's consumption for your linked fridge posted?
And ... anyone actually tested a low watt inverter on these?

 

[Artsyguy]

One of my kids drug one home from college. I put it on the deck, but it didn't seem to keep my beer cold enough. I tore out the motor and compressor, useless dividers, shelves in the interior and laid it on it's side. Installed PolyIso foam on all 4 sides (1" thick) and another 1" inside of door. sealed it all up and trimmed out with cedar plank paneling. Makes an awesome icebox. Put ice in it on Thursday, and still had ice on Monday. I also installed a drain hose with valve to drain. Works great!

 

[John61CT]

Electrical efficiency depends most of all on effective (thick) insulation, so if you don't need portable and can spare the space, make your own box, up to 4".

Next most important is good ventilation at the condensor and electronics.

For the 12V "Danfoss style" compressor fridges, Brand doesn't make much difference on efficiency, but yes build quality and longevity varies widely.

​Danfoss is now Secop

Dometic (Waeco, Adler/Barbour) is the 800lb gorilla

Engel uses Sawafuji.

Those three probably cover 90% of the consumer boating/RV/camper 12V compressor market.

~3-4A at 12 volt is the usage while the compressor is running.

There are bigger compressors for larger volume units, but they don't use that much more energy, likely because their boxes come better insulated.

The next big factor is temp differential, ambients over 100°, or using as a freezer increases proportion of time cycling on.

But ordinarily, 7-10 minutes per hour is pretty common, so 12-25AH per day.

 

[jonsun]

just an update. had controller with meter running since 9-27 here are the results





kicking the fridge on manually by opening the door causes it to run for about 2-3 minutes. this is recovered in a few minutes after compressor stops by the panels (230w). the controller jumps about 4 amps and drops to 13.4v which is my boost reconnect set point. the average daily draw has been about 175w.

this is 90 seconds after compressor shut down



after 3 minutes




as we can see the fridge is pretty efficient. that is about 35f internal with ice cubes in freezer and about 80-85f ambient. monthly count is off due to extended clouds and shore power boosting though. real daily use under testing has been between 300-500 watts.

 

[hugemoth]

Many years ago I swapped out the 120V compressor on a 1.7 CF with a 12V Danfoss compressor. Easy to do and worked great. It used 4 amps at 12V while running and duty cycle averaged 6 minutes per hour.

 

[jonsun]

So about the same then.

 

[mert6706]

One of my kids drug one home from college.  I put it on the deck, but it didn't seem to keep my beer cold enough.  I tore out the motor and compressor, useless dividers, shelves in the interior and laid it on it's side.  Installed PolyIso foam on all 4 sides (1" thick) and another 1" inside of door.  sealed it all up and trimmed out with cedar plank paneling.  Makes an awesome icebox.  Put ice in it on Thursday, and still had ice on Monday. I also installed a drain hose with valve to drain.  Works great!

I've been looking at coolers and refrigerators and am confused. I will either be in a car or a tent at RTR. Is there a small refrigerator that already keeps everything cold for a few days without having to add extra insulation? If not, then I'm thinking I might as well save some bucks and get a really good cooler. Then I wouldn't have to purchase a solar system just yet. Opinions? Advice? Thanks!

 

[John61CT]

Yes there are plenty, $400 is cheap, they get up to $1000+

$200 for batteries, $300 for solar, could go a bit cheaper or spend more.

Wiring, mounting, fuses, maybe a combiner.

If you just weekend a few times a year, ice is cheaper no doubt.

Fulltime boondocking, ice gets more expensive and of course very inconvenient.

 

[hugemoth]

So about the same then.

Only a small improvement over the standard 120V compressor, a bit better when you consider inverter efficiency of around 80%.

 

[jimindenver]

For me the easiest way to measure what 120 Vac loads take is with a clamp meter between the bank and inverter. This shows the actual draw from the bank for the equipment I am using. My killawatt shows what my A/C or fridge is pulling but not the inverter.

I do agree that a cooler and ice would be more practical for a one time or short trip. Put a few gallon jugs of water in a deep freezer a few weeks before you leave and you will be amazed how long they last. A cooler with the same capacity will be smaller than a 12v unit and certainly take up much less room than the solar and batteries needed to support it.

I think what is making the mini fridges more acceptable is the general push for better efficiency across the board. You still pay more for the most efficient but they really do use less power. (as long as you do your homework) Enough so that it is a real choice between a larger 12v unit and a 3 ft 2 door mini fridge that pulls a few more amps PLUS the extra solar and battery to support it. It really doesn't take much extra to cover those few extra amps a hour seen from that point of view compared to the huge gap in pricing.

To me it is finding the balance in the bigger picture. I see it differently because I do not have to deal with the power end of it. I could save more than the difference in draw simply by unplugging the things I am not using. So the extra capacity, better insulation and lower cost seem appealing now that I think of it. Someone else may have to consider much less room for solar, batteries, even the unit itself. In that case a few amps here and there really add up.