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Author Topic: Can you run propane/dc fridge from 12 volt converter circuit or not?  (Read 553 times)

Dodean

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Thanks for any information.
1985 Starcraft pop up
Converter 30amp, converter input 2.3 amps, converter output 15 amps
15 amp Circuit #1, 4 amp water pump
15 amp circuit #2, heater 1.6 amp and led lights 1.1 amps

Fridge states 8 amp 95 watt draw

I was curious if you could run an old domestic propane/dc fridge from one of the 12 volt converter circuits when plugged into a 120volt shore circuit.  The propane seems to be cooling but not to the level it should.  I know it may be the fridge as well.  Have done complete cleaning, basic stuff.

Lou Schneider

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Re: Can you run propane/dc fridge from 12 volt converter circuit or not?
« Reply #1 on: January 18, 2018, 02:25:57 PM »
Welcome to The RV Forum!

A converter that old (1985) most likely has an unfiltered output, and relies on the battery to smooth out the voltage.  Newer converters deliver clean power whether or not they're connected to a battery.

The refrigerator power draw of 95 watts suggests it's using the power to run an electric heating element in place of the propane flame.  The element itself doesn't care if the power is filtered or not, the question is whether the refrigerator has a circuit board that will be confused by dirty power or if the refrigerator has just mechanical logic (manual controls).

Gary RV_Wizard

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Re: Can you run propane/dc fridge from 12 volt converter circuit or not?
« Reply #2 on: January 18, 2018, 05:42:09 PM »
What fridge make & model?   8A @12v is indeed about 95 watts, so maybe that is the DC heater draw.  Whether the converter can deliver that probably depends on what else is drawing DC.  It would appear you could add an 8A circuit for the fridge, but with a couple lights on, a bit of battery charging, and then the pump cycles so you get right on the hairy edge. A more up-to-date converter/charger in maybe a 20A size would be a better bet, if you are willing to spend on that old PUP.

However, the chances that your fridge will cool better on DC than LP are slim.  Everything in DC mode is the same except the source of the heat that drives the cooling unit.   If anything, the DC heater is likely to be a bit cooler than the LP flame.  If the LP heater is working at all, the problem is almost surely elsewhere.

You should be able to find a service manual that covers your fridge at http://bryantrv.com/docs.html
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Madcow

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Re: Can you run propane/dc fridge from 12 volt converter circuit or not?
« Reply #3 on: February 15, 2018, 10:52:32 PM »
One has to wonder why the RV/TT OEM's haven't moved to 12v refrigerator freezers.  They can be had up to 10 CF..... 2.1 cube freezer, 8.2 cube fridge.  They run on 12v only and auto switch to 120v on shore power.  They are designed for some serious abuse.  I use them in heavy commercial trucks and have for most of this century.  My current one has covered almost 800,000 miles and been operating 24/7 for almost 6 years.   Keeps frozen foods frozen even with the truck shut off in over 100F heat.  Never had dairy go bad.   And mine can run for a couple of days with the truck shut off before degrading batteries too low.   And even the 10 cube version can be had for no more cost than a equivalent 8 cube 3way TT unit, and the 10 cube 12v unit will fit the spot a 8 cube 3way unit fits in.

This junk they are putting in TT's is so ancient and a rip off.
« Last Edit: February 15, 2018, 10:54:35 PM by Madcow »

Old_Crow

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Re: Can you run propane/dc fridge from 12 volt converter circuit or not?
« Reply #4 on: February 16, 2018, 03:11:35 AM »
Back in the '60's my dad's 16' TT had a 3 way fridge in it.  Propane, 120v, 12v.  You could only use the 12v while driving because the trailer only had one battery, and it wouldn't last the weekend running on 12v.  I believe that's why they got away from the 3 ways and went only gas/120v.
With the advent of newer battery technology, solar power, and destination camping people are going to residential fridges which are 120v only.   
Wally Crow
Retired 30 year ASE Master Auto Tech
Y2K Bounder 36S F53
'03 Jeep Wrangler Sahara

Gary RV_Wizard

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Re: Can you run propane/dc fridge from 12 volt converter circuit or not?
« Reply #5 on: February 16, 2018, 08:39:40 AM »
Quote
One has to wonder why the RV/TT OEM's haven't moved to 12v refrigerator freezers.  They can be had up to 10 CF..... 2.1 cube freezer, 8.2 cube fridge.  They run on 12v only and auto switch to 120v on shore power.

There is a fairly simple answer to that - a 12v compressor uses a lot more electrical power than a propane powered absorption fridge. It's the LP gas mode that is ordinarily used when no shore power is available, NOT the 12v power mode. Few RVs even have the 12v only mode (3rd way) - most are just LP or 120v. Smaller trailers and low end models are also typically limited in battery capacity as well, another penny-pinching factor that helps keep the base price attractively low.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL