35 replies to this topic

[pods8]

I picked up a new ARB fridge last week and wanted to get a general feel for the power draw it would have on my system before taking it out camping next weekend. So I ran this unscientific baseline test:

The fridge was sitting in the isle on my FWC, which remained closed up during the entire test (ie no vents open), my FWC sits outside. For batteries I'm running (2) PS-62000 6V 210ah batteries in series that are ~2.5yrs old but have been treated nicely.

For a quick thermal load I grabbed (6) 1/2gal jugs of water and threw them inside the fridge. The fridge stayed closed during the entire test which is less realistic but in general one should try to limit how much they're going in/out of these anyways.

Fri @ 6pm with an ambient temperature of 85F I loaded in the jugs and set the fridge to 32F. Both the fridge and my camper were plugged into 120V to bring the fridge temps down on 120V (which would be my normal practice before a trip) and to make sure my batteries were fully topped off.
Fri @ 10pm I unplugged the camper and the fridge was now on 12V; fridge 32F/ambient 72F
Sat @ 8:30am: Fridge 32F/ ambient 61F / batteries 12.85V
Sat @ 3:00pm: Fridge 31F/ ambient 86F / batteries 12.78V
Sat @ 7:30pm: Fridge 32F/ ambient 84F / batteries 12.73V
Sun @ 7:30am: Fridge 32F/ ambient 61F / batteries 12.74V
Sun @ 3:00pm: Fridge 31F/ ambient 77F / batteries 12.70V
Sun @ 7:30pm: Fridge 31F/ ambient 75F / batteries 12.68V
Mon @ 6:00am: Fridge 31F/ ambient 52F / batteries 12.67V
Mon @ 5:00pm: Fridge 32F/ ambient 89F / batteries 12.62V
Tue @ 6:00am: Fridge 32F/ ambient 57F / batteries 12.60V
Tue @ 5:00pm: Fridge 31F/ ambient 89F / batteries 12.51V
Wed @ 6:00am: Fridge 31F/ ambient 58F / batteries 12.49V
Wed @ 5:30pm: Fridge 31F/ ambient 91F / batteries 12.41V
Thur @ 6:00am: Fridge 32F/ ambient 57F / batteries 12.41V
Thur @ 5:00pm: Fridge 32F/ ambient 82F / batteries 12.21V (Fridge was running)
Thur @ 8:00pm: Fridge 32F/ ambient 82F / batteries 12.34V
Ended test.

Needless to say I'm quite comfortable with the battery bank to power draw match-up for easily sitting somewhere for a long weekend without needing to charge up the batteries at all factoring in there still be other users like lights/fans/etc.

[Alley-Kat]

I like these kinds of threads, thanks for the info.

May I ask what kind of independent temperature probe you used to measure the inside temp and where it was placed inside (high, low, near the cooling location or away from the cooling location)? Just curious.

Did you get any freezing?

[pods8]

For the inside temp it was just the arb set point, from other folks experience the fridge cabinet is usually 5-7deg higher depending on where you're checking. So in reality when I'm using the fridge I'll probably set it a bit lower that 32F on the dial to get the temps I want. For this test I was just trying to get a feel for ballpark power draw.

I do have one of these thermometers at home but I need to replace the battery to get an actual comparison of cabinet temps verse display: http://www.sciencela...R/21811/45-4039

No freezing at the 32F setting. When I ended this test I changed to set point down to 0F to see how long it'd take to freeze the jugs. This morning at 6am it was reading 16F on the display and the jugs were mostly frozen.

[SunMan]

Thanks for posting this, great info. FYI, I've been keeping mine set at 27-29F and that seems to give me "ice chest cold" beverages. Prolly draws a little more power but what the heck. I have yet to try to make ice with mine.

[pods8]

Thanks for the temp suggestion, after I started the test I read that 28F is what a lot of folks set it at (mine only goes in 2F increments by the way) but I didn't want to change it midway through. In general it was to just give me peace of mind that for my weekend warrior trips I've got nothing to worry about in terms of needing solar or running the truck periodically, etc.

I'm betting those jugs will be solid by the time I get home this afternoon!

P.S. I've ordered a couple types of 12V sockets from digikey to check out (mainly for my new build), I'll keep you posted if you're interested in doing the inline socket under your rear seat like we were talking about.

[EdoHart]

... So I ran this unscientific baseline test:

Unscientific? Reporting the raw data and the conditions in which you recorded it sounds like sound science to me.

[pods8]

Unscientific? Reporting the raw data and the conditions in which you recorded it sounds like sound science to me.

Eh, I did what I could but it's based on batteries with an unknown true amp hour rating now, just reported the fridge display temp, etc. Amp hour readings would have been what I'd consider more scientific.

Reporting raw data and the conditions I'd just consider good practice if you're going to post stuff in the first place. "My rig still started" doesn't really say anything useful in my mind.

[ski3pin]

pods8, really appreciate your post on this. This (along with all the other great electrical info you and others have posted) will be a great help in deciding on possible future DC refrigerator and solar needs. Again, thanks!

[SunMan]

P.S. I've ordered a couple types of 12V sockets from digikey to check out (mainly for my new build), I'll keep you posted if you're interested in doing the inline socket under your rear seat like we were talking about.

Please do, very interested. Just camped for 2 days using the cig lighter vice the inverter and would prefer mounting one near the battery to avoid the cord running front to back. My old blue top got the job done again but I did start it once just to be safe, was only getting a 12.2V reading on the second day. Was still showing 12.6V this morning from the short charge I gave it.

[Jeff Wanamog]

I have had several 12 volt refrigerators. Verts and horizontals. Nothing I have owned works like my ARB 50.
But......if you think it works well now, purchase the insulated cover for it. You will be amazed at how efficient it becomes. I love passing out popsicles when camping when its hot out.
Just my .02
Jeff