My new ARB fridge run test, 6 days of running battery voltage readings

[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.sciencelab.com/page/S/PVAR/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

 

[SunMan]

Good to know. I have wondered if the cover was more for the protection of the fridge than to insulate it. Now that the sting of the initial purchase has worn off the cost of a cover doesn't seem so bad.

 

[Ted]

I just installed a Engel SR70 in our camper. We have two AGM batteries and usually roll during the day, so we're not adding solar. First test in the driveway once installed was to turn the fridge on to setting 3, or middle temp. Ambiant temp was mid to high 90's. Camper was in the sun. Down to 38 degrees within four hours. Checked it the next morning, a total of 18 hours. Ice tray in freezer section was frozen. Battery monitor showed yellow while the fridge was running, but showed green once it was turned off. Will give it a camping test this weekend. Whether ARB, Engel, or whoever, seems like the electric only fridges are the way to go.

I love passing out popsicles when camping when its hot out.
Looking forward to pulling this one off.

 

[pods8]

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.


I got these two types in, I don't really like the fit with the ARB plug when it would come to road vibration. They would work fine standing still though. I'm going to use the type on the right for the power ports in my new camper.

To stick with the standard plug unmodified it'd probably be best to try and get a merit socket rather than a cig socket (you take that red piece off the stock plug to make the switch). I've only seen a few listed up on ebay while quickly searching so far:
http://cgi.ebay.com/12v-DC-power-MERIT-socket-fridge-Light-extension-/390212682711?pt=AU_Car_Parts_Accessories&hash=item5ada7d03d7

http://cgi.ebay.com/ebaymotors/Merit-socket-motorcycle-BMW-TRIUMPH-YAMAHA-HARLEY-/180563837919?pt=LH_DefaultDomain_100&hash=item2a0a7183df

However I'm leaning towards splicing in a set of SAE 2 prong connectors in the cord (with an inline fuse to replace the one in the main plug, they sell the connectors with heavier gauge wire available). Which will allow me to remove the stock plug to plug into a similar SAE 2 prong wire hardwired to my aux battery. When I want to take the fridge elsewhere I can plug the stock cig plug back in and use that with normal cigarette power locations.

 

[K7MDL]

My personal favorite for indoor 24VDC and 12VDC is the Anderson Powerpole. Standard is red and black for our 12VDC systems and it is also a standard for interconnect in ham radio usage so our radios might get power from others in emergency times. They do come in other colors. The smaller housing choices are 15 and 30 amps. Crimp or solder contacts, your choice. Easy to put together.

http://www.andersonpower.com/products/singlepole-connectors.html

These are carried by a lot of places, and also at local electrical supply houses and some of them in my local hardware store even. I buy them buy the bag since I use so many. For more weather resistant situations I often use the SAE however. Eastern Beaver and others (like solar suppliers) supply a bulkhead mount version with 12 or 14GA wire pigtails. Good for solar panel exterior exits. If you like weather sealed inline connectors you might look at the Sumitomo MT line like this page has
http://www.easternbeaver.com/Main/Elec__Products/Connectors/Sealed/SM-MT/sm-mt.html
These like many are crimp type. Also you can get SAE molded pigtails with weather plugs from that supplier.

http://batterytender.com/accessories/ring-terminal-harness.html An easy local source for these for most folks is a motorcycle store. Fuse, SAE plug and weather cover for about $7.50, all molded with ring terminals at one end. This was meant for putting on each vehicle battery in your garage.

While on the Battery Tender accessory page I just spotted this 100amp bulkhead connector that might be interesting for cabinets and solar http://batterytender.com/accessories/battery-connector-plug-black-1.html Overkill for a fridge, but might be convenient.

 

[SunMan]

I got these two types in, I don't really like the fit with the ARB plug when it would come to road vibration. They would work fine standing still though. I'm going to use the type on the right for the power ports in my new camper.

Thanks, I think I like the one on the right too. It would work fine for me as the fridge rides in the back seat while we are on the road and doesn't go into the camper until we are done driving.

 

[Desert Rancher]

The 2 pole connectors can be found at some hardware stores, order online/ship to store:

http://www.doitbest.com/Marine+equipment-Seachoice+Prod-model-13841-doitbest-sku-589802.dib

The cigarette type are at West Marine, stainless steel and waterproof.

 

[pods8]

My personal favorite for indoor 24VDC and 12VDC is the Anderson Powerpole.


We need to meet up, I'd like to see the powerpole connectors in person.

Right now I was just leaning towards the SAE 2 poles, this place has them with 12ga pigtails and good pricing: http://www.solarseller.com/low_voltage_dc_pumps__lvm__teel__accessories__plugs_and_extensions.htm


Thanks, I think I like the one on the right too. It would work fine for me as the fridge rides in the back seat while we are on the road and doesn't go into the camper until we are done driving.


What were you planning to plug the fridge into for driving in the truck though?

Those plugs run $3.9 on digikey plus shipping, or you can get a similar one from westmarine locally but they run ~$12. Seems like a decent plug for most 12v stuff but again I found it finicky in terms of fit with ARB plug so keep that in mind.

 

[SunMan]

What were you planning to plug the fridge into for driving in the truck though?

Those plugs run $3.9 on digikey plus shipping, or you can get a similar one from westmarine locally but they run ~$12. Seems like a decent plug for most 12v stuff but again I found it finicky in terms of fit with ARB plug so keep that in mind.


There is a stock 12V cig lighter plug in the back seat of my DC Tundra so it works great for travel. In theory I could just leave it in the truck as the ARB has a low voltage cut off but I would prefer to have nothing drawing off of my truck battery while boondocking.

Not surprised at the Westmarine pricing.

 

[MarkBC]

However I'm leaning towards splicing in a set of SAE 2 prong connectors in the cord (with an inline fuse to replace the one in the main plug, they sell the connectors with heavier gauge wire available). Which will allow me to remove the stock plug to plug into a similar SAE 2 prong wire hardwired to my aux battery. When I want to take the fridge elsewhere I can plug the stock cig plug back in and use that with normal cigarette power locations.

Hope this isn't too off-topic...but this photo prompted me to post this wiring-related "by the way":
On my recent camp on Pine Mt I was going to set up my solar panel (free-standing, not permanently mounted) and plug it into the receptacle I installed on the underside of my camper -- I use the type of connector shown in this photo. However, I discovered that the male tip on the end of the panel cable had broken off inside the female receptacle in the camper wall...must have happened last time I disconnected it on my last trip. This probably happened because I wasn't careful and just yanked it out, maybe off-axis -- not saying there's anythng wrong with this type of connector, and I'll replace it with same. Fortunately, I was able to pull the tip out of the hole with needle-nose pliers, so I don't have to replace the glued-in receptacle, just the part on the end of the cable.
Just thought I'd point out what can happen if not careful.

 

[pods8]

There is a stock 12V cig lighter plug in the back seat of my DC Tundra so it works great for travel. In theory I could just leave it in the truck as the ARB has a low voltage cut off but I would prefer to have nothing drawing off of my truck battery while boondocking.


You could just rewire that plug with a fused line to the aux. battery side of your seperator. I didn't realize you already had a plug back there you were using.