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04-24-2017, 06:37 PM
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#1
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Member
Name: ruth
Trailer: 1986 13' scamp
Pennsylvania
Posts: 42
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Install dorm frig
I want to replace my original ice box (have attempted to add insulation it didn't help) with a dorm frig. I would prefer 3way but cost of 3way and labor would be high. Any feedback on swap or if you've Been using elec frig what you've found will be helpful.....thanks
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04-24-2017, 07:01 PM
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#2
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Member
Name: Rod
Trailer: Scamp 16 Std Layout 4
West Virginia
Posts: 37
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Dorm Refrig Install
I'm in the process of installing a 120VAC only refrigerator in our new Scamp. We got the refrigerator at Lowe's and it's almost an identical fit with the 4.6 cu ft model from Scamp. I'm an old refrigeration guy and I'm adverse to "gas fired" refrigeration, although I do know that the new units are much more reliable and safe, but did I mention that I'm old? And set in my ways? Anyway, you're going to need a way to power the refrigerator while you're traveling or camping without park power. Most likely you'll want to install a small inverter (opposite of a converter) that uses 12VDC from the battery and inverts it to 120VAC. So there's still going to be some installation cost with the conversion, especially if you're not up to the electrical part yourself. I'm doing it mostly because I can (and I'm also Welsh/Scots, so I'm, well, "thrifty").
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04-24-2017, 07:16 PM
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#3
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Senior Member
Trailer: 2009 17 ft Casita Freedom Deluxe
Posts: 857
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We have a dorm fridge best described as a cube in our campster. It fits perfectly where the original ice box was. A prior owner ran the power down the back of the cabinet, out the lower door, and across the aisle. I'm in the process of rerouting it.
We haven't used it on a long trip, so I'm still evaluating the pros and cons. Our technique so far is to put blue ice in the freezer when it's plugged in and use that to help keep it cold while driving. It worked pretty well on our first trip. At some point, I will see if the solar panel has enough juice to power an invertor or run a hot cable to the battery from the truck.
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04-24-2017, 07:18 PM
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#4
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Senior Member
Name: bob
Trailer: 1996 Casita 17 Spirit Deluxe; 1946 Modernistic teardrop
New York
Posts: 5,413
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We put a dorm fridge in our Uhaul to replace the original icebox. Had to make a platform for it to set on, which is screwed to the floor and the fridge bolted to the platform. The day before we leave home we plug in the trailer to get the fridge cold. Just before heading out we put a couple frozen water bottles in. Plug in when we get to the campground. Food stays cold. This method has worked for us. When doing the install I left a 1" space around the front of the fridge for air movement, I did not trim around it to seal it to the cabinet face.
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04-24-2017, 07:53 PM
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#5
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Member
Name: ruth
Trailer: 1986 13' scamp
Pennsylvania
Posts: 42
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Thanks for all the feedback! Rod my aversion to installing the 3way is the gas. My nephew will help me. I did think about how or if I could run it while either driving or dry. Would you give me more info on what I would need to do and how long it could run this way? Thanks again
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04-24-2017, 10:49 PM
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#6
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Senior Member
Trailer: Escape 17 ft
Posts: 8,317
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I presume your tow vehicle runs on gas?
__________________
What happens to the hole when the cheese is gone?
- Bertolt Brecht
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04-25-2017, 09:36 AM
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#7
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Member
Name: Rod
Trailer: Scamp 16 Std Layout 4
West Virginia
Posts: 37
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How Long Will It Run?
Well, that is a variable question depending on so many details. I'm going to give you a quick summary of what I found with my installation and remember the formulas can be found in many places and the ones I used came from the Do-It-Yourself RV Forum. I didn't come up with this myself.
I also caution that picking and installing an inverter and batteries large enough takes careful research, planning, and in most cases, courage!
I'm not going to get into lot's of detail or definitions, but inverters are usually rated in Watts (W) and batteries are rated in Amp Hours (AH), so you need to figure out what you need. The wattage is found by using the refrig amps x AC voltage = AC Watts. My refrigerator says it uses .9 Amps, so .9A x 120V = 108W. Then the 108W is divided by 12V to get Amps (DC) = 9A(DC). Then that is multiplied by a constant of 1.1 = 10A(DC), so my refrigerator will use up 10A of battery power every hour.
Now I know I need an inverter that will provide at least 110W, but honestly I'd double that for conservative sake.
Grp 24 batteries are rated at 75 Amp Hours and you need to plan on using only half that, so figure 37.5 available amp hours, so my refrig pulling 10A would last about 4 hours. Two grp 24's would then go over 7 hours. I'm using two 6V golf cart batteries with 450 Amp Hours (divided by .5) and 225 usable amp hours, so my 10A refrig should run about 22.5 hours.
Of course that's all theory, so again, research, consider, plan, and then do it again before proceeding. It could get even more expensive that the three-fuel models.
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04-25-2017, 09:42 AM
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#8
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Member
Name: Rod
Trailer: Scamp 16 Std Layout 4
West Virginia
Posts: 37
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Addendum to How Long
As others will probably note, you could keep the batteries charging by possibly using solar or a generator, but that can get expensive and time consuming as well. And I'm not sure how they might work when traveling.
Isn't our new hobby fun!?
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04-25-2017, 12:34 PM
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#9
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Senior Member
Name: Gordon
Trailer: Scamp
Idaho
Posts: 223
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Ruth,
You might consider a compressor-based fridge that will run on 12V or 120V. That way you can operate it on shore power when available, or use a battery(ies) when you're off the grid. Not real cheap, and it requires some research, but this would allow future alternatives without propane. Using an 120V mini fridge from a discount store on an inverter in your bouncy camper is a questionable process for many reasons, from what I've read.
Rod,
No offense, but I think some of your numbers may be off. Those 225 amp 6V golf cart batteries that you refer to are still 225 amps when connected in series to provide 12V, and usable amps are half that. On the plus side, refrigerators don't usually run continuously, maybe 1/4 - 1/3 of the day, so your amp hour requirement is less.
Glenn,
You're just a smart alec. You knew what she meant.
Gordon
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04-25-2017, 12:53 PM
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#10
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Senior Member
Trailer: Escape 17 ft
Posts: 8,317
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Quote:
Originally Posted by Gordon in Idaho
Glenn,
You're just a smart alec. You knew what she meant.
Gordon
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Just trying to point out that people fear things that they are not familiar with, like propane, yet, they will fill their car with gasoline. Benefited me, as I was given a Coleman propane stove and a lantern because of such fear.
__________________
What happens to the hole when the cheese is gone?
- Bertolt Brecht
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04-28-2017, 08:47 PM
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#11
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Member
Name: Rod
Trailer: Scamp 16 Std Layout 4
West Virginia
Posts: 37
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You Caught Me
Hey Gordon, I fell right down the old parallel vs series hole on that one. Nice save! The fact that the refrigerator really doesn't run continuously helps lots! I usually use the worst case scenario when I'm doing this kind of thing and then hope for the best case.
Ruth, sorry to make that seem so complicated. We conservative, engineering types tend to be ultra cautious! You can probably run your small refrig on a fairly small inverter and a standard battery if you're lucky enough to have park power when you settle down for the evening. As I noted earlier, I tend to prepare for the worst case and oversize everything. Still, please check out some of the other discussions to help make your choices.
Glen, no problem with propane; I've got a stove/oven and the gas/electric HW tank. I just don't like having combustion in small places that I can't easily see and work with. And whenever anything can work on multiple "fuels" it just has to be more complex i.e. more expensive to own and service. Or at least that's my opinion (and welcome to it!) after forty years working around HVAC stuff. I like my combustion big, like in boilers.
Thanks to all of you who continue to help the rest of us out when we need it most!
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04-28-2017, 10:42 PM
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#12
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Senior Member
Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,879
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Quote:
Originally Posted by kayleigh0302
I want to replace my original ice box (have attempted to add insulation it didn't help) with a dorm frig. I would prefer 3way but cost of 3way and labor would be high. Any feedback on swap or if you've Been using elec frig what you've found will be helpful.....thanks
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The problem with the dorm fridge is that it draws power almost continuously, and that power is 120 volts. It doesn't draw a lot, but it's relentless. So, you have to be plugged in or always supplying it somehow.
If you decide to run it on an inverter, you'll need the inverter and the batteries to supply it. But then you'll have to charge the batteries sufficiently to keep up, all the time. If you are counting on solar, you'll need enough to carry you through cloudy weather and through the night. So now you have to add solar, batteries and an inverter to support the fridge.
This will become a problem as you rely more on the fridge and the value it brings to the party.
Why not just go ahead and pay a bit more for a propane fridge? They are reliable and silent. They work all the time, day or night, sunny or not, driving or camped, and they don't need the infrastructure required for a 120 volt only unit. Yes, you'll have to get propane to it and vent it. Once you are plugged in you can go back to shore power to run it and eliminate any propane use.
It's fine to be stubborn, but really, at some point, jumping through all the hoops to have a reliable refrigerator that doesn't run on propane may not be worth the hassle just for the dislike of a small gas flame. It's definitely not worth the hassle for everyone. A reliably cold fridge is a marvelous thing. Propane fridges make life easy and simple while camping.
On boats, I've experimented with a dorm fridge, a 12 volt marine fridge, a 120 volt and a 12 volt system custom built into my own box, a holding plate system and various methods of expelling the waste heat. Propane fridges don't work on boats, so I've only used them in my various campers. Now, I just mostly leave the fridge in my Ollie on, running on shore power at home. When we go, I simply switch it to propane and do nothing else until we get back and I return it to shore power. This means food can wait there until our next trip and we can even have frozen items when camping.
If you don't have a reliable fridge, you can't have frozen food.
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
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04-29-2017, 02:09 AM
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#13
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Senior Member
Name: Dave
Trailer: Casita SD17 2006 "Missing Link"
California
Posts: 3,738
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Hi Ruth, I have to agree with Raspy's post 12. A two way,120v/LP refer will fit the bill. Yup, they are pricey but I've only had to replace one in over 30 years. The 3 way units do work for some running 12v while towing but that all depends on your alternators output and wiring gauge. Dedicated 12v refers like a Truckfridge work well but entails other equipment such as solar and heavier batteries if you're not on shore power. Dave B can fill in the blanks on that as they do a lot of boondocking with theirs. But bottom line, at least to me, if you're only doing weekends or a week or two camping at a time, the two way is your best choice over the old RV icebox. Also, if you only do shorter trips, you might consider one or two GOOD ice chests may work out for you too. OK, that's my two cents worth .
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04-29-2017, 07:25 AM
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#14
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Senior Member
Name: John
Trailer: 1979 Boler 1700
Michigan
Posts: 2,048
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Nova Kool fridge
Another viable option is a Nova Kool 3.5 cu ft compressor fridge which consumes 2.2 amps @ 12vdc when running. With a 50% duty cycle, this fridge consumes 26 amp hours per day, so with a 200 amp hour battery it could run 4 days without recharging...
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04-29-2017, 08:52 AM
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#15
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Senior Member
Name: John
Trailer: 1979 Boler 1700
Michigan
Posts: 2,048
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Nova Kool fridge scenario again
Quote:
Originally Posted by John in Michigan
Another viable option is a Nova Kool 3.5 cu ft compressor fridge which consumes 2.2 amps @ 12vdc when running. With a 50% duty cycle, this fridge consumes 26 amp hours per day, so with a 200 amp hour battery it could run 4 days without recharging...
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... also in the above Nova Kool scenario, a 100 watt solar panel might be able to power the fridge indefinitely, or MUCH longer than 4 days.
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04-29-2017, 11:53 AM
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#16
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Senior Member
Trailer: 13 ft Boler
Posts: 1,174
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We have a 3way fridge out of an old tent trailer in our boler.
It only works on 110 ac. We plug it in as soon as we get to the site and unplugging it is the last thing we do when leaving.
In over 10 years and multiple 100s of nights in the boler we only lost food
once that I remember and that was when the fridge quit on us.
It needed to spend a day upside down then it was fine again.
We insure the fridge is plugged in for a day before we leave or use a cooler and ice on the first day out.
Fred
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04-29-2017, 12:00 PM
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#17
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Senior Member
Name: bob
Trailer: 1996 Casita 17 Spirit Deluxe; 1946 Modernistic teardrop
New York
Posts: 5,413
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I'm with Fred, that's what we do with both our Uhaul that has a 110 dorm fridge and the Casita that has only a two way I think but we only run it on 110.
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04-29-2017, 01:04 PM
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#18
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Senior Member
Name: JD
Trailer: Scamp 16 Modified (BIGLY)
Florida
Posts: 2,445
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The dorm fridge is a lot cheaper than a 12 volt/120 volt or LP, b ut the inverter has to be a little bigger for the starting surge.
A small 300 watt inverter would do.
A drawback would be that the inverter will have it's idle current running continuously, but it's a relatively small amount.
The refrigerator will cycle on and off at about 50% duty cycle and draw anout 40 watts. a little more accounting for the losses in the inverter.
The key here is that the inverter has to handle the starting surge. after it starts you are home free.
My Norcold swing compressor runs on 12 dc or 120 vac and has an inverter to chop the 12 volts into 24 v ac at 60 hz for the compressor, the 120 vac is stepped down to the same voltage for that side of things.
The swing compressor has no starting surge, but is noiser than a rotary compressor.
The Norcold also draws about 40 watts (or 50 maybe, but the duty cycle is still about 50% so the overall power draw may be very similar.
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04-29-2017, 02:16 PM
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#19
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Senior Member
Name: Mike
Trailer: 2012 Escape 19
Oklahoma
Posts: 6,018
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The "Truckfridge" brand has about the best prices for the efficient 12V fridges containing (what was previously known as) the Danfoss compressor. They probably are more durable than your typical dorm fridge.
I had a dorm fridge in my previous Burro and it was pretty useless for my camping pattern of long drives to reach a no-hookups destination. The dorm fridge would be warm after about 3 hours without power. But solar panels were more expensive back then. Now if I had at least 220A of battery and 250W of solar, a conventional fridge could work for me. But a Truckfridge (or similar) could do the job with half as much battery and panel capacity, and it would be built to withstand more of the bouncing and jarring (because, let's face it, how many dorm rooms hit potholes?).
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04-29-2017, 02:25 PM
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#20
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Senior Member
Name: Charlie
Trailer: 2014 Lil Snoozy
North Carolina
Posts: 788
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We have a Truckfridge. The best thing about it is it just works. It ran all day on our group 24 battery. We just installed two 6v golf cart batteries in our LiL Snoozy. In my test they powered our empty Truckfridge for three days and nights and were still at 60 percent.
Denny Wolf tried to run a dorm fridge off an inverter. It worked for awhile but eventually would not start. You can read his blog at "wanderingourway at wordpress"
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