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tombiosis
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# Posted: 27 Jul 2014 11:51
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Hi
I have a chance to buy a nice size dometic propane fridge out of an RV for my cabin. From what I can tell the fridge requires constant 12v power to keep running. If I hook up a car battery to the 12v and run it on propane, how long will the battery keep it going?
Would I be better off getting an older fridge with a pilot light that doesn't require 12 volt to run?
I usually go to the cabin for 4 or 5 days max., and I thought if I had one of those mini solar panel chargers for the battery I should be ok...
any advice appreciated before the deal disappears!
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razmichael
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# Posted: 27 Jul 2014 12:10
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The rv propane fridges I have seen or used are two or three way. When running on propane they do not require 12 volts. For basic cooling. Some may have fans installed at the back to improve air flow (often done as a mod with lots of online designs and discussions) or a fan inside to help with internal distribution but the basic propane mode does not need power. The flame is very small like a pilot light. The fridge may also have the option to run off 12vdc and/or 120ac. The 12 volt mode is designed more for traveling and being run from the tow vehicle. This mode draws a lot of power and is not really suitable for a any other situation as it will drain your battery quickly (it is running a heater from a battery). General uses case is to pre cool the fridge with 120 at home, run on 12 volts while traveling and the. Switch to 120 or propane at the destination depending on what is available.
I suspect the fridge is propane with a 12 volt option (two way) or maybe 3 way. It should not need 12 volts except for accessories. Keep in mind these are designed to have the rear absorb option portion with the burner on the outside and are likely not rated for inside use. This you should investigate how you plan to install it. Also be away that these will only drop the temperature. Certain amount below the ambient temperature so have some limitations.
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creeky
Member
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# Posted: 27 Jul 2014 12:29
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Dometic is not the most reliable. From watching various Internet sites. So make sure it works. The 12v drain, as long as you're running it off of propane, should be low. You're looking at dsi (direct spark ignition). A good warm weather option.
Google the model # for more info.
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tombiosis
Member
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# Posted: 27 Jul 2014 12:40
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I tried googling the model (Dometic RM2611) and came up empty...but I did read about similar models and downloaded a manual.
The fridge requires constant 12v to regulate I think...it re-ignites the flame as necesssary...so no pilot light. There is a control panel on top of the unit and if it is not powered, no fridge!
So...how long will a car battery keep the little panel and re-igniter working? anyone have experience with one of these fridges?
My eyes are getting sore from surfing the 'net so I just want some experienced advice
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skootamattaschmidty
Member
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# Posted: 27 Jul 2014 12:46
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I wonder if you call an RV dealership in your area and ask the service guy questions about the fridge. They may be very helpful.
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razmichael
Member
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# Posted: 27 Jul 2014 12:55
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Sorry, obviously I had not considered the option of a 12v starter to light the propane when needed. Ignore my post! All my experience was with the older models where you "manually" started the
Fridge and only adjusted the temp by controlling the propane.
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creeky
Member
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# Posted: 27 Jul 2014 14:35
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Dsi and a 12v controller for the light, spark and control module. Now the question is... what does the manual say for amp draw and what is the size of the battery.
Deep cycle battery? Car battery precharged? Charging with how much solar?
Lol. Really. Did I ask three questions? Now that's just funny.
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tombiosis
Member
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# Posted: 27 Jul 2014 14:52
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I believe the draw is .30 amps...deep cycle marine 12volt, with one of those crappy little solar panel chargers on it...the panel is only 6 inches wide by 12 inches long...you see them on car dash boards and in boats etc...probably doesn't do much I'm guessing...
I don't mind haling the battery back to town between trips...just hoping I can get 5-7 days operation out of the fridge's 12 volt draw...?
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tombiosis
Member
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# Posted: 27 Jul 2014 14:52
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what is Dsi creeky?
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creeky
Member
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# Posted: 27 Jul 2014 15:42
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you'll be fine.
and having a bit of fun here: by way of explanation
.3a x 24h = 7.2a (for those just following a = amps and h - hours)
solving:
deep cycle marine battery at 100a (est.) / dod / days = okay?
(depth of discharge = dod)
therefore: 100a / 7 days = reliable performance * dod.
or
14 amp hrs per day capacity over 7 days, at no recharge = okay with 7.2 amp hrs per day
= a 50% depth of discharge after 7 days. I know: doncha love math...
looking 50% dod up on an internet table for cheap lead acid batteries = 1000 cycles or 2.7 aprox years. this varies but, probably less as you're recharging at 7 days and other variables ...
so if you add some solar input you will achieve better than 50% dod over 7 days ; and with lead acid that means longer life span.
i'd say looks good. i'd use a bigger / more solar myself. but it ain't my money.
er, as noted: dsi = direct spark ignition. hence no pilot light.
hence! lol.
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MtnDon
Member
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# Posted: 27 Jul 2014 18:45
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As far as I know all new RV and recent propane fridges require a 12 volt power source to run the electronics that make things work. No 12 VDC and nothing works.
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buckybuck
Member
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# Posted: 27 Jul 2014 20:24
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I have a Norcold rv propane refrigerator that also requires a constant 12 volts to run. It runs just fine for at least three days straight on just a Wally World marine battery.
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tombiosis
Member
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# Posted: 28 Jul 2014 11:02
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thanks buckybuck...have you ever ran it longer without re-charging the battery?
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buckybuck
Member
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# Posted: 28 Jul 2014 12:20 - Edited by: buckybuck
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No, but I'm fairly confident it could at least a few more days. The only reason I know it will work at least three days straight is because sometimes I have run it that long without recharging, when I've been at my place for a weekend and it's either cloudy or I'm simply too lazy to hook up the solar panel. And keep in mind I'm also running a water pump and a couple of LED lights, as well as whatever parasitic charge things like the rv's co detector need
I don't know how much running it three days straight damages the battery or what percentage charge it's at at the end of that time. I go to my place to relax, not to fret about things like that. I have been using this same battery for four years now. I can live with getting four or five years out of an $80 battery.
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beachman
Member
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# Posted: 28 Jul 2014 15:14
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Been on vacation installing solar and painting (lugging, fixing, etc...). Anyway, we have a Dometic RGE400 about 8cf refrigerator/freezer that runs solely on propane although you can run on electric but not efficiently. It was expensive but it works great and uses very little propane. It has a starter like a BBQ - a button and a light to ensure it is burning properly. We leave this going pretty much all summer and have no problems with it. We have an older Servel in the old camp and it still works great. Make sure these are cleaned often to avoid Carbon Monoxide fumes - we have never had problems (some will say it only takes one time) but our places are pretty airy. We will probably install a CO2 detector sometime soon just to make sure.
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tombiosis
Member
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# Posted: 29 Jul 2014 10:21
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beachman, how is the light powered?
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MtnDon
Member
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# Posted: 29 Jul 2014 12:48
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4 D cells
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beachman
Member
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# Posted: 30 Jul 2014 19:43
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Tombiosis, the lighting inside the fridge is a small bulb powered by 4 D batteries (MtnDon is correct) held at the back of the unit. You have to pull the thing out to change them or to remove them in the Fall, but good time to check the burner. I have a flexible gas pipe that makes this easier.
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RLamoureux
Member
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# Posted: 11 Dec 2017 10:47
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Tombiosis,
Our main cabin propane fridge is from Propane Outaouais
It runs on propane and has HSI ignition. However, we have 4 six volt (380 Amp-hr each) deep cycle batteries connected to two 400 watt panels.
We initially had an old three way from an old camper. It would last a week on a cheap Canadian Tire marine battery. I'd usually swap out a fresh battery every weekend and recharge the dead one at home.
Cheers,
Richard
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