Edgestar fridge actual power consumption numbers

[susswein]

I picked up a scratch-and-dent edgestar 63 fridge right before the new year, and decided to do a couple of experiments to see what the actual power consumption was. I'm sharing the info here in case anyone else is interested:

Testing setup:

In order to make the tests repeatable I performed them inside my house, where the thermostat keeps the temperature at 68 during the day, and drops it to 62 at night. Prior to each test I let the fridge run for several hours in order to bring it down to the desired temperature. I conducted the tests with the fridge plugged in to a 120V ACoutlet via a kill-a-watt meter. The kill-a-watt meter keeps track of the total watts consumed over a period of time as the fridge cycles on and off. In each case I conducted the test with the fridge empty, and didn't open it during the test period. Each test ran for 24 hours.

Results:

Test #1: Thermostat on the fridge set to 34 degrees. Total watts consumed in 24 hours: 400 Equivalent Amp-hours at 12 volts: 33.3 Compressor ran for just over 6 hours, a 25% duty cycle.
Test #2: Thermostat on fridge set to 0 degrees. Total watts consumed in 24 hours: 760 Equivalent Amp-hours at 12V: 63.3. Compressor ran for just under 12 hours, a 49% duty cycle.

Notes:

In the first test the fridge is set to 34 degrees below ambient temperature. This is probably a decent approximation of useage in the NW or the high country of Colorado. Test #2 is 68 degrees below ambient, which is probably a good approximation of useage in the desert southwest. The amp-hours shown assumes that the fridge's efficiency when running on 12V DC is the same as the efficiency when running on 120V AC. This probably isn't precisely correct, but is probably within 15%.

If anyone in the salt lake area has an ARB or an Engel I can borrow for a couple of days I'd be happy to test them under the same controlled conditions and post a comparison.

I also plan to try some of the modifications suggested elsewhere on EP and also add additional insulation to the sides and top. I'll post those test results here in the future.

 

[4x4junkie]

Good to see more factual info on these fridges. There has been quite a bit of speculation about them no doubt (a lot of it pretty far off according to some testing I've done on my own FP430).

I'm thinking you may want to run your tests with some amount of mass inside of it though, otherwise the temperature inside won't be as stable which may cause the compressor to consume more energy by cycling on & off more often than it needs to.
Also, if you can get ahold of a good deep-cycle battery (or an equivalent external power source with an output set to 12.5VDC), I think it may give a better indication of what a person can expect it to draw when powered up in a vehicle. The built-in 120VAC - 12VDC converter unit adds at least another 20-30% more energy consumption to the unit which is pretty significant (plus the additional heat it generates inside the same compartment occupied by the compressor).

I took info from the following (very well-written) article for my tests. Though a bit dated, it does have some figures for the Engel unit you asked about.
http://www.expeditionportal.com/res...rland-journal-portable-12v-fridge-review.html

 

[susswein]

Thanks for the suggestions. I'll run the tests again with some thermal mass (AKA a few six packs) inside and see if there's any difference. As far as running the tests on 12V DC, the problem is that I don't have a 12V equivalent of the kill-a-watt meter to measure accumulated watts or amp-hours over time. Something like a link 2000 would be perfect, but it's hard to justify the price. I could add another 200 watts of solar for the price of the link 2000!

Where did you get the 20-30% efficiency drop in the 120VAC to 12VDC converter? The kill-a-watt showed a 65 watt draw while the compressor was running, which is pretty darn close to the 5A at 12VDC that it's spec'ed at (65 watts vs. 60 watts, or a difference of 7%).

 

[MarcFJ60]

If I recall correctly, my test results were similar to 4x4Junkie's. I had mine hooked up to a car battery through a logging multimeter. I put two one-gallon jugs of water inside to approximate a partially full fridge. My results were posted in the big Edgestar fridge thread, probably a few pages after 4x4Junkie's results.

Edit: http://www.expeditionportal.com/forum/threads/23350-Cheap-Fridge-lt-400-shipped?p=899022#post899022

I guess I didn't post as specific results as I thought, but you get the idea.

 

[4x4junkie]

Where did you get the 20-30% efficiency drop in the 120VAC to 12VDC converter? The kill-a-watt showed a 65 watt draw while the compressor was running, which is pretty darn close to the 5A at 12VDC that it's spec'ed at (65 watts vs. 60 watts, or a difference of 7%).

Past experience with common power supply/converter units I've used for various equipment. I'll admit I have not measured the actual Edgestar's converter for efficiency, however I certainly can feel it putting off a fair bit of heat which is all additional power consumed that wouldn't be present on 12VDC.

For my tests, what I did initially (since I also don't have a fancy Kill-A-Watt equivalent for 12V) was simply monitor & record it's current draw on a multimeter (a Fluke 87v DMM set to DC Amps), and monitored how much current it draws while the compressor runs, how long it runs for during each cycle, how long it was not running each cycle, and finally the total length of each cycle (this after being allowed to stabilize overnight with the room temp also stabilized at 80°).
Each cycle it ran for approx 14 minutes, and was off for approx 16, so roughly 47% duty in almost exact half-hour cycles.
Current draw was approx 3.9A average while running, and 0.042A when not. Averaging it out for 48 cycles in a 24 hour period I arrived at a figure of 44.8 AH over a 24 hr period @ 12.6VDC.

But then I remember my Fluke meter has an "Average" mode on it (duhhh!!! ), so I decided what the heck I'll run the test again and just leave it set on that for awhile. Several hours into it I see the display beginning to stabilize pretty good at maybe a hair under 1.9A, which correlated pretty well with the 1.87A I had calculated from my previous testing, so I pretty much left it alone there.
If you have a meter (DMM) with an 'Average' function, certainly that'll free up some time and save you some math lol.



Edit:
this was with the thermostat set to maintain the fridge at a 30° internal temp (same as done in the article) measured with the Fluke's temp probe, as well as with a small porch-type thermometer I put inside it.

 

[whitenoise]

Thought I'd add to the discussion with my data. Fridge is an 86qt Edgestar, stock 12V power cord with a GT Power RC130A meter wired in-line. This is actual usage during an expedition, with the fridge being stuffed to the gills with food. The voltage is at the end of the time period. Obviously, there is quite a bit of voltage drop in the factory power outlet wiring. Car still started fine at the end of each time period despite low voltage shutoff.

 

[LocalmotionSC]

I'm dredging up a really old thread, sorry about that, but because this is a popular topic that I and many others keep coming back to I thought I'd add my 2c.

First, thanks for taking the time to test properly and providing your data, it is quite hard to find actual power consumption data for these fridges, and even harder to find good comparisons between brands. Expo/Overland Journal have done a few but they don't make the effort to do a proper test, they just list the maximum amperage from the spec sheet which is a horrible way of approximating real world power draw.

Where did you get the 20-30% efficiency drop in the 120VAC to 12VDC converter? The kill-a-watt showed a 65 watt draw while the compressor was running, which is pretty darn close to the 5A at 12VDC that it's spec'ed at (65 watts vs. 60 watts, or a difference of 7%).

I'm not sure where they arrived at the 20-30% number, but I wanted to point out that the measurement you took via your Kill-A-Watt cannot account for (1) the conversion inefficiency of your inverter, that alone is an 8-20% efficiency drop, and (2) any parasitic draw of the inverter (power the inverter consumes just sitting there), this would only be factored in if the fridge is the only thing that requires the inverter to stay on 24/7.

On another note, I wonder if you ever had a chance to test any other fridges or redo the test with some thermal mass. If so (and you still have the data) I would be interested to see the results.

 

[Herbie]

I ran as good a test as I could manage back in 2011. Results are posted here.

I used a lab power supply, precision shunt, and DMM logging to a PC to measure actual DC current into the fridge. This was basically a "steady state" test and doesn't account for opening for removing/adding food or changing environmental conditions (both of which would be hard to control anyhow.)

 

[LocalmotionSC]

Bumping a very old thread, but I found this energy consumption / battery + solar sizing spec sheet from Whynter (same as Edgestar) that is very helpful. Hopefully others will find it useful to: