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Old 06-10-2013, 05:31 PM   #29
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Naples, FL , Hood River, OR
Join Date: Dec 2005
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IMHO, a 3-way fridge that uses a 12VDC heating element is one of the biggest wastes of energy I have ever seen in an RV!

First and most importantly, the 12VDC operation relies on a 12VDC heating element to attempt to replicate the heating found from your 120VAC heating element when connected to shore power. Assuming a 240 watt (they are actually higher) 12VDC heating element, that will draw 20 amps from your battery every hour of operation.

It also has a lower heating capacity than the 120VAC element, and will NOT cool the fridge, as it was never designed to do this. It's sole function is to attempt to maintain whatever cold temps are found in the fridge when you start it on 12VDC heating. It has a hard time doing even this!

As for longevity of your battery bank while on 12VDC heating, assuming that you have a newer Airstream with 2 OEM group 24 batteries, you would have a total battery capacity of 160 amp/hours. Since you should only draw that amount down to half, than gives you a useful battery capacity of 80 amp/hours, which translates into just 4 hours of fridge use while on 12VDC.

And don't expect your charge line from your tow vehicle to help much either. Most trailer wiring does not accept much more than 5 amps from the TV.

OTOH, a marine style fridge with a Danfoss compressor system will draw around 3 amps while on 12VDC, and about 1 amp on 120VAC. The numbers are much better (26 hours of continual operation from 80 amp/hours), but it presents you with other problems, like keeping your battery bank charged. Solar is the way to go with a marine fridge!

Lew Farber...ABYC Certified Master Marine Electrician...RVIA Certified Master Tech ...AM Solar Authorized Installation Center...AIRSTREAM Solar & Electrical Specialist...Micro Air 'Easy Start' Sales and Installations
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Old 08-01-2013, 05:13 PM   #30
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2017 25' Flying Cloud
west plains , Missouri
Join Date: Sep 2009
Posts: 105
Dometic lp issue when moving

My refrigerator works well when parked, but the lp fails on the road...please help! Please email ideas.

I would love to get a helpful call as we are in the mountains for 3 months...thanks...jack. 417 293 2487

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Old 08-02-2013, 01:13 PM   #31
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1966 24' Tradewind
1995 34' Excella
Lynchburg , Virginia
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[QUOTE=Hoonanea;1306832]Great to hear the good news! One of my "favorite mods under $100" was a $10 remote thermometer from Walmart. It has a large display that shows indoor temp and outdoor temp via a remote sensor. I put the remote sensor inside the refrigerator rather than outside the trailer. This helps me monitor the temperature inside the refrigerator and I don't have to open the door. [QUOTE]

Thanks! That is a great idea. I am going to get one. I just installed a new fridge and I
want to keep track of how well it cools in hot weather. BTW I took great pains to add insulation around the fridge and to install baffling behind the fridge to make sure the air flow goes through the condenser and not around it.

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Old 08-03-2013, 04:10 AM   #32
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2012 27' Flying Cloud
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We used a different strategy this time than with my original post. Last night I brought 2 bags of ice and a case of refrigerated waters to the trailer while in storage. I put each bag of ice in its own HUGE ziplock bag (those massive blue ones for storing sweaters) figuring they would melt until the fridge cooled down. Our fridge has a blue plastic shelf on the bottom shelf/rack covering the drawers. I took that out figuring if the ice melted and the bags failed at least most of the water would go in to the drawers.

One bag of ice on the bottom shelf, cold case of water on the middle shelf and second bag of ice on the top shelf. Propane on, set fridge to 5. Stared at the trailer for an hour thinking about camping and watched fridge temp stuck at 60...

When we got to camp about 20 hours later, fridge was at 33 frosty degrees and not only had no water leaked, the ice bags were still about 90% ice cubes (which we promptly added to the adult beverage chest) and the little bit of melting stayed in the zip lock bags.

Happy as a clam! Hope that works for others.
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Old 08-03-2013, 07:57 AM   #33
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1977 27' Overlander
1954 25' Cruiser
1990 34.5' Airstream 345
VC Highlands , Nevada
Join Date: Mar 2005
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Originally Posted by rjack View Post
My refrigerator works well when parked, but the lp fails on the road...please help! Please email ideas.

I would love to get a helpful call as we are in the mountains for 3 months...thanks...jack. 417 293 2487
Jack - I'll call you - had the same problem for YEARS! My problem turned out to be too much cooling airflow going through the back of the fridge when we were going down the road. I baffled the louvred access door and that solved my problems.

I had a thread on all that I did to discover the problem and how I fixed it.

Buttercup's Web Site. WBCCI #17330, 11281 & 7830. VAC Past President, TAC NV-2 & NV-3
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