Greetings friends.
I bought the following-
(2) Ampere Time 300AH batteries
(1) Victron Smart Shunt
(1) Norcold N10DC 12V only Refrigerator
I thought I would post my preliminary findings as to power consumption. I am doing this mainly to help decide how to size my future solar array, etc.
I have the refrigerator set up in my garage. I put some packages of frozen vegetables and popsicles in the freezer. I put the obligatory beer and soda in the refrigerator section. This in an effort to create a somewhat realistic scenario.
My garage had an ambient temperature of +/- 90 degrees for most of the day. 80s into the evening.
I have been using the Victron IPhone app to monitor the batteries.
I started up the refrigerator at 5:00pm on July 9.
As of 7:30am on July 11- My phone indicates that the refrigerator has used 101.3 Amp Hours.
I may post further about this. I just thought this may be of interest.
I always enjoy reading the forum. Thank you to "regulars". I have learned much from you.
-FT
So, it sounds like a total of 38.5 hours for the total of 101.3 Ah or you are taking 2.631 Ah out of your batteries for each hour of operation. For the Norcold Polar 10 series, they say 8.5 amps in the day, 6.2 in night mode. Using their calculations and averaging about 7 amp draw, that's over 3 days to run your fully charged 600 Amp Hour battery bank down to 10.5 volts. Your testing would indicate longer.
How about checking the hours it takes your fridge to reduce the voltage to 10.5V?
Pierce
I have a straight 12 volt fridge in our U300 with 500 watts of solar , I used the 12 volt wires that were with the three way fridge I replace three years ago I did the same test while we were in az last winter. Our fridge is a Ever Chill I can't remember what the results were but will conduct the test again and post the results.
Hello Pierce.
I think their nameplate current numbers must be based on startup and the lowest acceptable operating voltage.
I am able to see the demand expressed on a 2-hour chart within the Victron phone app. A cursory glance at the charts shows something near 20 minutes "on", 5 minutes "off". This is with the temperature setting on 5- the coldest setting. The charting is not recorded so I took a couple of screen shots from my phone so I could sample a few intervals.
I am not sure if I will be letting it go down to my 10% battery shut off in the near future. If I do, I will post the results.
The experiment will continue!!
Thanks for the response.
-FT
Thanks to FT for this good info. Sounds like the reefer is running at full output based on your 20/5 minute runtimes. When installed will you run it at 5 degree setting? Is it strictly on/off for the compressor or does speed modulate based on load?
It would be interesting to see a comparison to one of the 125VAC, similar size type installs.
Hello Chuck.
I am going to start with the #4 setting which is the factory default.
It seems the temperature control is strictly on/off. The manual says that when "night mode" is initiated that the compressor will run at half speed. Night mode will give way to standard mode after eight hours by default.
Thanks for your interest.
-FT
Naturally, the big advantage for dry campers/boondockers with the 12V fridges is there is no inverter needed. Less solar and a smaller house battery bank. I would be nice to have an automatic timer to go into night mode.
Pierce
That was my thought process in giving this unit a try Pierce.
I almost forgot to mention- I have have a timer for night mode. She will remind me every couple of evenings.
-FT
When the unit is in your coach I wonder what the temps will be around the unit?
Dry camping will most likely not be much higher than my test temperatures. I will be chasing 70s like most do.
If hook-ups are available most likely lower as the AC will be on.
-FT
Reading your post got me looking at 12 volt fridges and I found this site and they sell
11 and 17 cubic 12 volt fridges. The prices don't look too bad and I have no idea of the
quality.
RV Refrigerators for Upgraded RV Kitchens | Way (https://www.wayinterglobal.com/collections/refrigerators)
Greetings again.
I know- Doing math on a forum is risky!!
The experiment interrupted for now. Here are the latest results-
1. Duration: Two days seventeen hours and twenty-three minutes or 65.383 hours.
2. Total Consumed Amp Hours: 162
3. 162AH/65.383 hrs= 2.477AH
Note: Refrigerator/Freezer were set on 5 for all but 10 hours. The 4 setting was used for 10 hours.
Night mode was not used.
My projected run time for the refrigerator on my 600AH battery bank.
I will assume 540 AH usable to maintain at least a 10% state of charge.
(540 available AH/2.477AH)/24hrs= 9.084 Days. Refrigerator only load
I will update with the installed real world results if and when they become available.
I am not sure if the test period was long enough to include any defrost function, etc. I had to shut it down now.
Best to all.
-FT
Based on what others have posted, and if I am correct to size solar for 2 time usage you would only need 60 watts of solar to break even.
So, I went online to find a 120V, 10 cubic foot stainless refrigerator with top freezer and found several at Best Buy. Here is an example of one that is energy star compliant. https://www.bestbuy.com/site/insignia-10-cu-ft-top-freezer-refrigerator-with-reversible-door-stainless-steel/6449413.p?skuId=6449413 The current draw is about 15 amps or twice as much as the same size Norcold Polar 10 cu ft. In the real world for dry campers, the total would be a little higher as the inverter would have to run at night plus the 12V Norcold Polar consumption drops to only 5 amps in the night setting.
So, not so good for the residential except it costs $410 vs over $1500 for the Polar. That's a lot of change diesel especially since I bought an almost new 2000 watt sine wave inverter for $60. Bottom line is solar will easily run a resident fridge all day with no penalty but the inverter will have to kick in for the evening hours.
Since RV fridges must have 12V to operate even when on propane, there is a small draw to operate the circuit board and to keep the gas valve open. Should be less than 2 Ah.
Why do RV fridges cost so much and why don't residential refrigerators come with better compressors? Seems a good way to cut the grid usage and dependence on as much oil. Once again, the RV owner gets the short end of the straw. An efficient compressor motor does not cost an additional $1100.
Pierce
The nice thing about the 12 volt fridges is the compressor runs all the time, just slows down
and speeds up according to the need. At least the good ones do that.
I posted my 10.1 CU foot residential numbers recently after monitoring over 900 hours with watt meter in our coach. Average consumption 2.8 amp per hour on battery. Magic Chef 10.1. 65 watts at 120 volts while running.