BajaNomad

Truck camper fridge questions

blackwolfmt - 4-25-2017 at 05:57 PM

Ok so I got a truck camper what is the most efficient way to run the fridge gas or electric as in 12 volt battery ? for the longest time, use the battery and a solar maintainer ?? all opinions welcome

[Edited on 4-26-2017 by blackwolfmt]

Howard - 4-25-2017 at 06:43 PM

I have had different types of class "A" campers and now have a dual slide on a F350 dually and by far the electric plug in gets it colder faster, keeps it colder and is cheaper if at an RV park. ( or at a friends :))

Sorry for the hijack but I will be putting my rig up for sale soon if anyone might be interested. U2U me so this does not get hijacked.

chuckie - 4-25-2017 at 07:05 PM

Electric to get it cooled down and gas to maintain it is what I do..

blackwolfmt - 4-25-2017 at 07:05 PM

No prob Howard anytime, Once I thought about it plugged in would be No prob,, I was lkn for battery 12 volt times frames with a 12 v maintainer solar charger vs propane

blackwolfmt - 4-25-2017 at 07:32 PM

Quote: Originally posted by chuckie  
Electric to get it cooled down and gas to maintain it is what I do..


Thanks Chuckie

Paco Facullo - 4-25-2017 at 08:53 PM

I have an ARB 12v fridge. And love it. It protects your battery from getting too discharged as it will shut down before. Also draws little so a solar backup is a great way to go.
Not cheap BUT quality.

BooJumMan - 4-25-2017 at 10:10 PM

Newer style 12v fridges are very efficient. ARB, Engel, Dometic, Edgestar...many others... They run about 60w or less. A 100-200w solar panel is sufficient to keeping the battery topped off during good weather. A 3 way style with propane/gas is always nice if planning on staying put for a very long time, but I think these days, the electric, low draw 12v Danfoss swing compressors are the best.

msteve1014 - 4-26-2017 at 08:35 AM

Quote: Originally posted by blackwolfmt  
No prob Howard anytime, Once I thought about it plugged in would be No prob,, I was lkn for battery 12 volt times frames with a 12 v maintainer solar charger vs propane


You will need more than a battery maintainer to keep up with the heater in the frig on 12 volts. I believe it is to keep the frig cool while you are driving from one place to the next, then you change to gas, or 120ac.

BFS - 4-26-2017 at 10:07 AM

If you have a 3 way camper fridge you will most likely drain the battery pretty quick if using it exclusively while camping. Gas will last much longer. As someone mentioned above, the most efficient way is to plug it into your house the night before you leave, then in the morning move the setting to your battery while driving, then turn on the gas while camping.
Have fun!

8knots - 4-26-2017 at 11:30 AM

My truck camper has the typical 3 way fridge. If you are cooling it down before a trip using the propane it takes a good overnight to get cold. I never thought about using electric to chill quicker. That being said....these refers are so efficient on propane it is crazy good. Just got back from 5 days remote camping and I never worried about running out of propane. You can go a really long time without refill as long as you have 20 or 30 lb propane tank.

mtnpop - 4-26-2017 at 12:51 PM

Dealers always told us to stay away from using the 12v with the fridge.. use the gas and 110v when avail.
Do not remember what the explanation was unless it really wipes out your battery faster.... you can travel with the gas on....
This was from Lance camper dealers....
Always had really good luck with gas setting on ours....

have fun

chuckie - 4-26-2017 at 12:59 PM

I should have said, use the 110 to cool it down and then switch to propane..Propane lasts a long time...

blackwolfmt - 4-26-2017 at 01:27 PM

mucho gracias for the great info fellow Nomads

hermosok123 - 10-15-2017 at 09:42 AM

I keep a big 5th wheel with a Dometic 3 way in Gonzaga. In the hotter months when it gets above 90f it begins to loose efficiency and when it humid. They sell these small solar powered fans that help lift the hot or warm air out the exhaust stack. My fridge runs 10 degrees cooler with it operating. I have no experience with the newer models but will look into them. I learned this trick; if you want to freeze all the stuff in a fridge just take the access door off of the freezer compartment. For long off grid trips we use a portable propane cooler and rotate food from the now freezer.

surfhat - 10-15-2017 at 11:58 AM

After using 3 way propane fridges in the past decades, and now have a Dometic 12v only, there is no comparison. No need to level the vehicle, no need for carrying propane tanks.

The efficiency of these modern electric 12v compressor driven fridges is the cleanest way to go. That I have a couple of agm batteries to run it and a pv panel on top, is a natural for unlimited refrigeration, or freezing, if that is desired.

With these current 12v compressor driven fridges and their efficiency, why would anyone cling to gas driven fridges ?, unless they don't have any 12v batteries to run these systems endlessly without burning fossil fuels.

!2v electric is the way to go. These fridges in a top loading design are all the better for not letting the cold air fall out every time you open them up.

The previous gas run fridge I had dumped out the cold air every time I opened it up . There is a better option and 12v top loading electric is it. Thanks to all here.

blackwolfmt - 10-15-2017 at 01:46 PM

Well I camped out at 8500 ft in the San Juans for 130 dys, June and july were pretty much blue sky with full sun everyday so my Solar panel kept the battery 12.5 and I would use gas to really cool it down couple hrs a week 20lb tank would last around 5 wks. Then Aug and Sept cloudy rainy almost every day plus el sol was getting lower in the sky and was behind some trees most of the day couldn't keep the charge up on the batt so started using gas full time on the fridge gas would last around 15, 20 dys. Dometic fridge is very efficient would stay 40 on low setting,will always have gas around for cooking and taking a hot shower and when it started gettin down to 25 the heater really came in handy


chrishaynesusa - 10-15-2017 at 07:27 PM

I run a set of ARB 50Liter Refrigerators and a dual battery setup(soon to be three)

One fridge for frozen food <32F
One for cold food. >32F

2 batteries for Refrigerators and one for starting.
all three can be slaved together for starting or winching.

And a 200 AMP Mean Green Alternator.

nbentley1 - 10-16-2017 at 02:58 PM

I have a 86Qt Edgestar that I've been running for a few years, connected to the truck / trailer when travelling and 160W folding solar set up when stopped for anything longer than an overnight. Set up works great.

PaulW - 10-17-2017 at 08:21 AM

BTW, No mater how you manage the power for you electric frig/freezer please get a jump start device for backup. If you are alone and have dead battery it is not a good thing.
Your experience will vary and solar is good as is dual batteries. It all comes down to what if?
The cost for the top power units go from $160+ down to 67+. Compare the battery power of the Lithium Ion battery and get one with that has the best power to dollar ratio. Forget about options like reserve power like Consumer Reports likes to rate highly. All you want is max cranking power.
Very good insurance for back country use.

aguachico - 10-17-2017 at 10:16 AM

Running house devices off of starter battery is a bad idea, period. Deep cycle batts are cheap, charging them is very easy and cheap.

Hook - 10-17-2017 at 07:01 PM

Whatever you do, DO NOT RUN AN ABSORPTION (PROPANE STYLE) FRIDGE ON THE 12V SETTING, IF IT HAS ONE!!!! I am not talking about the 12v current that is supplied to the control panel. I'm talking about using 12v to cool the fridge. Even with current supplied by your vehicle's charging system, it is unlikely that enough current is getting through the small gauge wiring that connects your truck to the camper's house battery. The draw is something like 20 amps at 12 v. And if you forget to switch to propane when you stop for lunch, you can do your house battery serious damage unless you have something that cuts off the power at about 11.5 volts.

12v COMPRESSOR fridges are great, but you better have enough battery capacity and solar generation to support it.

aguachico - 10-18-2017 at 06:17 AM

The new 12 volt fridges have sensor protection build in. I'm lusting over the Dometik or the ARB

PaulW - 10-18-2017 at 07:38 AM

True the RV absorption frig's do not have a 12v low voltage cutoff. A serious omission in the design. I always stop for lunch with the thing on 12v and have no issue with the house battery. I guess because the frig is already cold. Of course if the house battery was old it sure would be an issue.
The portable frig/freezers do have the low voltage cutoff settings. However I let mine sit 4 days with the frig on and car parked and the result was no start. I had the voltage cutoff set at the mid point. So constant cycling at that cutoff point was enough to lower the battery so the thing would not start.

Hook - 10-18-2017 at 07:46 AM

Quote: Originally posted by aguachico  
The new 12 volt fridges have sensor protection build in. I'm lusting over the Dometik or the ARB



Those are probably not absorption fridges. It's the older, 3-way absorptions fridge's 12v setting that is the real power robber.

I have found the best of both worlds in continuing to use my 6 cf absorption fridge with my 40 qt Norcold compressor fridge. The absorption works SLIGHTLY better on 115v than propane, but I can go a long time on two, 7.5 gallon propane tanks. I am rarely plugged in to grid current when camping. Not a fan of RV parks. So, all foods go into the absorption fridge and all beverages go into the compressor. I can keep beverages in the low 30s and not have to worry about damaging produce. The small absorption freezer keeps the few frozen things frozen, but also makes ice each night for mixed drinks. I leave home with a gallon ziplock of cubes and make more each night in camp, when necessary.

However, I am not able to make enough to take any kind of sizable ice chest out in a boat. That requires a purchase and is the only ice I have bought on the road in the last 5 years of travel. Nice not having to deal with melting ice.

The problem I find with the compressor fridges is that you have to buy the larger ones to have a separate refrigerator and freezer section and that gets expensive fast. And then you have reduced your refrigerator section to a very small amount. Beer is a big space hog. Did I mention that beer is a necessity?

You can rebuild the "guts" of an absorption fridge for much cheaper and keep the increased capacity. There are also lots of decent Dometic absorption fridges from the early - mid 2000s out there that simply have a defective control board that owners never replaced. Dinosaur makes great after-market control boards that fix the problem and give you more control over the cooling process. Leveling has never been much of an issue for me; I dont want to sleep in the camper on an uneven surface that would make an absorption fridge inefficient, anyway. That's what the orange "legos" are for.

PaulW - 10-18-2017 at 08:09 AM

Hook,
Of interest for day trips I have a Dometec CDF11 (1.5 liter) compressor frig/freezer. Works like my 50 liter one I use for camping. The CDF11 is targeted for the cross country trucker segment as it is a 12v only unit, For precooling I use a 110/12v converter. It has the 3 voltage cutoff like the big one. It has the dual compartments deep one for coldest and upper small one for warmer things. Holds a large quantity of 12 oz cans or typical water bottles. Wide range of pricing so be sure to shop around for the best price.
Sure nice to get rid of buying ice. Obviously it would work on your boat depending on your electrical system and battery size.
BTW, the cup/drink holders are not cooled, just for convenience. I see some off road rigs that are using this unit to replace their console.

chrishaynesusa - 10-18-2017 at 10:17 AM




mtgoat666 - 10-18-2017 at 10:30 AM

Quote: Originally posted by chrishaynesusa  





looks fancy!

but it seems a bit impractical as it leaves no room for luggage, kids and dogs

chrishaynesusa - 10-18-2017 at 10:35 AM



Roof rack for luggage, front and rear seats for passengers.
trailer for gear :grin:





[/threadjack]

[Edited on 10-18-2017 by chrishaynesusa]

aguachico - 10-18-2017 at 01:16 PM

:o Bad ass looking rig.

Hook - 10-18-2017 at 03:36 PM

Mr. Haynes, thanks for the pics of your incredible rig.

Not being too familiar with ARB fridges, do you set one for freezing and one for 35+ ?

blackwolfmt - 10-18-2017 at 04:05 PM

yeah really NIICCCCEE Rig for sure:bounce:

chrishaynesusa - 10-19-2017 at 10:33 AM

Quote: Originally posted by Hook  
Mr. Haynes, thanks for the pics of your incredible rig.

Not being too familiar with ARB fridges, do you set one for freezing and one for 35+ ?


Yes , one for freezing stuff and one for cool stuff. :)

Hook - 10-20-2017 at 10:45 AM

I didnt mention that I do have a Kyocera solar panel on my camper. I have seen it put out (reading at the charge controller) as much as 8 amps @ 14.5 volts. For my purposes, preferring to camp off grid, I dont think I would consider using a compressor fridge without one. We will sometimes be in one location for 7-10 days, so no driving to charge the house battery. If you are moving every other day, solar might not be necessary.

My 40qt Norcold compressor fridge draws 2.1 amps @ 12v, according to the spec sheet. I have no idea if that is 2.1/hr or 2.1 amps while the compressor is running. On a fridge setting, it probably kicks in about once every 10 minutes in an ambient temp of 80-85 degrees F. Probably runs for 3-5 minutes.

I also have a battery separator between the truck batteries and the house battery that allows charging (in either direction) when voltage in either location exceeds 13.2 volts. The charge controller is a two-bank controller that allows you to send 50/50% or 90/10% of its charge to the house/truck batteries, respectively. I use the 90/10 setting.

It also isolates the two systems below that 13.2 threshold, so while it could be possible to run down your house battery (low sunlight for multiple days, high draw for some reason), the truck batteries are protected.

I actually did make up a jumper cable that bypasses the battery separator, if I wanted to combine the battery systems below 13.2 volts. But so far, the solar panel has made that unnecessary.

The jump start units really arent an option for most diesel trucks. Just not enough CCAs. My truck uses two GP 27 sized batteries as starting batteries.

This is all basic stuff for owners of most types of RVs with solar. But I thought I would write it up for those with conventional vehicles who are considering adding a compressor fridge and a solar panel and controller. If there is some way you can shoehorn in a "house" battery and isolate it, it's real peace of mind.

truck camper fridge question

hermosok123 - 10-24-2017 at 06:05 PM

How big is your panel and what size and brand charge controller are you using. Thanks

Hook - 10-24-2017 at 07:57 PM

Just looked for the paperwork on the system I bought. Cant find it. But my best recollection is that the panel was a 140 watt panel.

I do have the info on the charge controller. It was the Morningstar Sunsaver Duo and I bought the remote meter, too. It will accommodate up to 25 amps of solar power across two battery banks. It also compensates for temperature at the controller, itself.

My system is now about 7 years old. I paid just over 300.00 back then, including wiring and mounts for the panel. The battery was extra.

Hook - 10-25-2017 at 08:51 AM

Addendum: Originally, I bought a group 31 Lifeline battery. It was 290.00 from that guy in Texas who sells the most in the US. HIs was the best price, at the time. But it only lasted five years; mostly because it spent 10 months a year in Mexico. The heat of May, June and part of July and part of October, probably took its toll on its life expectancy. Five years isnt bad, but the Lifeline distributor told me guys in the Pac NW can get 10 years, because their temperature range rarely exceeds 80, nor below 50.

I have replaced it with a conventional, fill-occasionally, group 31 Interstate battery for less than half the cost. I dont really have to have a sealed battery, as the camper has an exterior compartment that is easy to access.

For anyone with an eligible Big Three vehicle, this is an interesting product. It's a battery box that hangs from the underside chassis. Can be wired to your existing truck charging system with their wiring harness, too. This would be an out of the way source for a primary or secondary house battery.

https://www.torklift.com/automotive/hiddenpower

aguachico - 10-25-2017 at 12:14 PM

Quote: Originally posted by Hook  
Addendum: Originally, I bought a group 31 Lifeline battery. It was 290.00 from that guy in Texas

https://www.torklift.com/automotive/hiddenpower


Lifeline batteries are great. I have two group 27 batteries in my boat. They are not cheap, but handle any conditions are supposed to hold the military contract for batts.

Buckland - 11-20-2017 at 01:20 PM

I have the Isotherm 12V 65L. Great fridge, quiet, super efficient. Have a 160 W solar panel and 2 AGM batteries. Never ram out of juice or cold beer!

Hook - 11-20-2017 at 04:54 PM

Quote: Originally posted by Buckland  
I have the Isotherm 12V 65L. Great fridge, quiet, super efficient. Have a 160 W solar panel and 2 AGM batteries. Never ram out of juice or cold beer!


Show us your unit, please.

DC only? Fridge only? Fridge/freezer? Chest type or built-in?

David K - 11-20-2017 at 05:03 PM

Quote: Originally posted by Hook  


Show us your unit, please.


Careful Hook, Doug wants this not to be any more than PG-13 stuff! :lol::lol::lol:

blackwolfmt - 11-20-2017 at 06:30 PM

Quote: Originally posted by Hook  
Quote: Originally posted by Buckland  
I have the Isotherm 12V 65L. Great fridge, quiet, super efficient. Have a 160 W solar panel and 2 AGM batteries. Never ram out of juice or cold beer!


Show us your unit, please.

DC only? Fridge only? Fridge/freezer? Chest type or built-in?




Now dat is funny:lol:

since were on XXX I still luv my dometic 3 Way the propane its a great backup when the sun aint shinning to charge the battery

rts551 - 11-21-2017 at 08:52 AM

Some of you keep talking about top loading refrigerators....I have not seen any of these built into campers. Are we talking 2 different issues or am I that far behind the times?

woody with a view - 11-21-2017 at 06:52 PM

Ralph, they mean ARB style aftermarket refers. Not your typical built into a pop up or cab over.

aguachico - 11-21-2017 at 07:22 PM

I'm looking at this unit, It can do freezer or fridge. I like to vac seal meats for a weeks worth of camping So as I load the freezer with vac sealed fish or seal meat, I can remove the the meat to eat. Then eventually before packing to leave for home both sides will serve as a freezer with all vac sealed meats ready for transfer. Best thing is getting back without a any meat to process.

https://www.dometic.com/en-us/us/products/food-and-beverage/...

rts551 - 11-22-2017 at 08:43 AM

Quote: Originally posted by woody with a view  
Ralph, they mean ARB style aftermarket refers. Not your typical built into a pop up or cab over.


I see. Wasn't the OP talking about a built in frig? Maybe the thread morphed.

woody with a view - 11-22-2017 at 09:02 AM

Not sure, my atteention span is shrinking these days.

Ken Cooke - 11-22-2017 at 10:18 AM

I have the Dometic CFX-65DZ (CFX 65 Quart dual zone). It works great at keeping my fruits, vegetables, and mineral water refrigerated. I use the freezer compartment to keep my vegatable burgers and Indian food meals frozen). I usually pack some tuna sandwiches for the road, and this is much better than using an ice chest.

msteve1014 - 11-22-2017 at 10:21 AM

Quote: Originally posted by rts551  
Quote: Originally posted by woody with a view  
Ralph, they mean ARB style aftermarket refers. Not your typical built into a pop up or cab over.


I see. Wasn't the OP talking about a built in frig? Maybe the thread morphed.


Yes, and yes. Now lets talk about fishing. It all runs together right??

PaulW - 11-22-2017 at 10:25 AM

The Dometec and arb and many other portable frig/freezers work great, but to use in a camper/travel trailer/5er/motorhome the thing would have to sit on the floor and use up valuable space. Baja Nomads has several threads exactly for portable Frig/freezers. Take your discussion there.
This thread was supposed to be about the 3 way units commonly used on campers/travel trailers/5ers/motorhomes not about the portable frig freezers.
Having said that I find the most efficient usage for a 3 way is to use it on Propane when dry camping and 110v in an RV park or at home. 12v usage works as long as the battery survives which can be long or short depending on age and its amp hours. A 12 volt battery may work for many usages in the camper, but the 3way frig/freezer will probably be the most severe usage and kill the battery the fastest. I always use mine on the 12v setting when connected to the tow rig with the motor running. This avoids turning off the propane when stopping to fuel the tow rig. Its always good to practice safe procedures. It is also the law in many states that require no propane systems can be active when traveling thru tunnels. Another safety issue.

rts551 - 11-22-2017 at 12:12 PM

Quote: Originally posted by msteve1014  
Quote: Originally posted by rts551  
Quote: Originally posted by woody with a view  
Ralph, they mean ARB style aftermarket refers. Not your typical built into a pop up or cab over.


I see. Wasn't the OP talking about a built in frig? Maybe the thread morphed.


Yes, and yes. Now lets talk about fishing. It all runs together right??


I suppose...My Samsung refrig works great on 110. I tried it on Propane...damn thing blew up.

Hook - 11-23-2017 at 10:19 PM

Just to clarify, there ARE purely electrical, 12v or 110v, upright compressor fridges, WITHOUT PROPANE CAPABILITY, that can be built in to existing truck camper fridge openings. The doors open outward, like a conventional home fridge. They are not cheap......but neither are the traditional 3-way (propane, 12v, 110v) fridges that originally came with the camper. Most camper companies now offer these as an option. They have been around for ages in boats, where propane is disdained by some. They have begun to put them in RVs for a few years now.

The "table-top" style fridge/freezers are much cheaper (still not cheap, though) but MOST force you to choose between fridge and freeze. USUALLY, you have to go up to the 65 qt size or larger (still not that big, really) to have separate fridge and freeze compartments. There are exceptions.

It is VERY nice to have the capability of using propane for being off-grid in areas where clouds are common or trees are tall and dense. Seriously, I suspect a 5 gallon propane tank might power my 3 way fridge for about three weeks in ambient temps around 80 degrees during the day and 60 degrees at night. My camper has TWO, 7.5 gallon tanks.

Keeping the rig level is important, but it doesnt have to be completely level. It still works fine.

I always drive with my fridge in the propane setting. Some campers I have owned are more prone to blowing out than others. I check it at each stop.

I honestly think if I was buying a new RV, I would still go with a propane capable one over a compressor. You have to begin thinking about sun exposures, solar panels, multiple batteries, possible generator use, finding 110v for serious battery charging, with a compressor.

Propane is easy to find everywhere. Mexico, US, Canada. Very off-grid friendly.

[Edited on 11-24-2017 by Hook]

Ken Cooke - 11-23-2017 at 10:26 PM

Quote: Originally posted by PaulW  
The Dometec and arb and many other portable frig/freezers work great, but to use in a camper/travel trailer/5er/motorhome the thing would have to sit on the floor and use up valuable space. Baja Nomads has several threads exactly for portable Frig/freezers. Take your discussion there.
This thread was supposed to be about the 3 way units commonly used on campers/travel trailers/5ers/motorhomes not about the portable frig freezers.


Whoops! I read the subject and immediately chimed in without investigating the earlier posts. Buy, so far, my Dometic fridge has been great! I'll watch for more fridge threads so that I can brag about my fridges USB connectivity.

aguachico - 12-26-2017 at 10:12 AM

Got a Dometic dzw-95. It is easy to lift because it is not too long. Preliminary testing shows it seals well and doesn't cycle often.
'
They use a slight of hand trick calling it a 95 liter fridge, when actually it is 85 liters internally.

Field testing to come.

Cliffy - 12-27-2017 at 02:13 PM

Back to the OP-
I have an old 120 volt/gas ABSORBTION style refer in my TT. All refers that use propane are called ABSORBTION refers by the way they work. They have no electric driven compressor. They use heat and a gas transfer in a sealed coil to effect the cooling process

The ones with a 12 volt side have a probe (@6" long) that gets very hot and is next to the "boiler" of the refer sealed coil so as to heat the special liquid within and run the cooling process.
The propane burner heats the same "boiler" without using any electricity.
The electric probe is using around 350 watts of electricity. At 12 volts this is @ 29 amps. 10 hrs of usage is @ 290 amp hrs. Well beyond your battery capacity.

I use the propane side all the time ( I shut it down getting gas, no big deal). I have 2 7.5 gallon propane tanks and have never had any problems. I can run it on one tank for weeks.

If I had hookups I would use the electric side for extended stays. Save the cost of propane.

Hook - 12-27-2017 at 04:45 PM

Some people report that their absorption fridges work best on propane, but the two I have had always worked best on 110v. I also think it is more resilient to being unlevel on 110v.

mtgoat666 - 12-27-2017 at 05:54 PM

Traveling sure is whole lot less complicated camping out of a pickup truck or suv, getting by with just a couple of iced coolers :light:

Hook - 12-27-2017 at 09:08 PM

Quote: Originally posted by mtgoat666  
Traveling sure is whole lot less complicated camping out of a pickup truck or suv, getting by with just a couple of iced coolers :light:


I disagree. It's more complicated.

Keeping things dry. Draining away water. Keeping them in a cool environment. Making ice runs, if you are camping in one spot for a week or more.

Ice is a pain in the ass. The only good place for ice is in a drink.:smug:

bajaboy1 - 5-7-2018 at 10:04 PM

I have a 6 cu. ft. Dometic fridge in in my cab over camper. It doesn't work very well on propane or electricity. When camping, when the temp gets over 85 or 90 degrees it just doesn't cool. I keep a thermometer inside the fridge and sometimes it gets up to 60 degrees or so. Thinking of buying a new one, but don't know which works the best in hot weather. All manufacturers say theirs is the best. Tried exhaust fans and inside fans. Nothing helps when beach camping on hot days.

Timinator - 5-8-2018 at 07:00 AM

If you have a 3 way fridge;

12V while driving after everything is cold from either being plugged in or propane. The 12V side uses a lot of amps to try and keep the fridge cold. It's also wise to rewire your RV electrical plug to the fridge with at least a 10 gauge wire, 8 gauge is best.

110V Always when you have it available

Propane Other than the initial cool down over night plugged into 110V this is how I run all my RV fridges. It's efficient and a propane tank can run a fridge for weeks and weeks, maybe even a month or more.

As somebody else said, if it's not a newer RV fridge, put a small solar powered fan in the fridge areas outside door to push out the heat to the roof stack/exhaust. It will make it cool much more efficient. If you're at a camp site without electrical hookups, you can even open your outside fridedoor (with screen) a bit to allow more fresh air up through the system.

A small fan inside the fridge also circulates the air inside and helps too, especially if the fridge is an older one.