Need ideas for replacing little stock fridge with taller "apartment" style AC fridge please

[Stevo]

I'm going to be living and traveling in my 18' Sunrader so I need a lot more space than the stock fridge holds. I'm thinking of buying an AC only "apartment" fridge/freezer and run it with an inverter in my motorhome. (I don't want a propane fridge and I don't want to spend a fortune on a DC fridge.) I'm going to have about 250 watts of solar with probably 3 house batteries.

I have a couple questions please...

1) How much less efficient percentage wise is an AC only fridge running off an inverter compared to running a DC fridge?

2) The opening width of the side door on my Sunrader is only XX" wide (Can't find the measurement now!) so I'm wondering how the heck I'd get a larger fridge in there since most of the apartment fridge freezers are around 21" to 22" wide? Since I'm doing a major remodel of my Sunrader anyway I was thinking I could make it so the back window could be removed so I can get the fridge in and take it out if I have to. Has anyone replaced their little stock fridge with a tall narrow AC fridge/freezer? Or how about making the large back window be removable? Any ideas please?

Thanks

Steve

[Skydancer2992]

You can often buy DC fridges (the ones like a large cooler at garage sales or maybe craigslist). One could be used to augment the current model already in your Toyota.

The motorized fridges use a lot of juice, especially on startup. The peak inrush current might be two or three times rated amperage.

Most upgrade projects involve a route through the passenger side cab door, removing the passenger seat first.

A strong friend or two are usually required.

Beer or pizza or both might be useful bribes.

[Stevo]

I already own an 83 quart DC Edgestar cooler and after using/experimenting with it the last month or two I decided I don't like having to fish through everything piled on top of each other. I'll be gutting the interior of my Sunrader anyway so these are things I need to plan for now.

Thank you

[linda s]

I would look for a small 2 door fridge. Always more energy efficient to not have to expose the freezer to warm air unless you need something from there

Linda S

[Bob C]

I tried a small dorm size refrigerator on an inverter and it would not run. I don't know if it was the type of inverter or what. The inverter was a 750/1500 peak unit so it should have been big enough. I have been told that some electric equipment will only work on a true sine wave invertor.

[DanAatTheCape]

check pplmotorhomes - I got a replacement for mine - they had one in stock with a good price.

as for going with non propane - unless you have quite a battery bank & way to charge those batteries I do not think it will work acceptably.

if you want to use ac or dc you pretty much need to be plugged into shore power or have the vehicle engine running.

you will also need a large inverter. the math can be found on line. it has to be big enough to start the compressor motor too.

[zero]

I'm going to be living and traveling in my 18' Sunrader so I need a lot more space than the stock fridge holds. I'm thinking of buying an AC only "apartment" fridge/freezer and run it with an inverter in my motorhome. (I don't want a propane fridge and I don't want to spend a fortune on a DC fridge.) I'm going to have about 250 watts of solar with probably 3 house batteries.

I have a couple questions please...

1) How much less efficient percentage wise is an AC only fridge running off an inverter compared to running a DC fridge?

2) The opening width of the side door on my Sunrader is only XX" wide (Can't find the measurement now!) so I'm wondering how the heck I'd get a larger fridge in there since most of the apartment fridge freezers are around 21" to 22" wide? Since I'm doing a major remodel of my Sunrader anyway I was thinking I could make it so the back window could be removed so I can get the fridge in and take it out if I have to. Has anyone replaced their little stock fridge with a tall narrow AC fridge/freezer? Or how about making the large back window be removable? Any ideas please?

Thanks

Steve

I've got two RVs with "dorm type" AC compressor refrigerators running off inverters. For me and the way I use my RVs, it has worked great. Both my AC refrigerators are 26" tall by 18 1/2" wide by 21" deep. I also have an RV with a Norcold 12 volt compressor fridge. There is little difference in efficiency between any of them. The key is how much insulation they have. When running an AC fridge with an inverter you get around 5% loss which isn't much to worry about. The key issue is HOW you use your RV. An AC refrigerator and 1200 watt mod-wave inverter can run about 2 full days on a pair of type # 27 deep cycle batteries without a serious discharge. The way I use RVs, there is never two days when I haven't started the truck engine and let the batteries charge back up - so it all works fine.

Note that you can add insulation to any electric refrigerator and make it MUCH more efficient.

I also have a cabin with a 6 cubic foot 12 volt compressor chest-refrigerator. It runs all summer with a pair of 120 watt solar panels and one battery in the dark NY Adirondack woods. In an area of better sunlight, it would work with a single 120 watt solar panel. It is a Sundanzer 5.8 cubic foot refrigerator that is made to run on 12-24 volts DC. On 12 volts, it uses an average of 1/3 rd an amp per hour at 70 degrees which is amazing. It has walls with 6" of insulation.

An RV sized fridge of the size you want can run on an average of 2-3 amps per hour at 70 degrees F. if well insulated. 250 watts of solar in my area will yield around 2 amps per hour, on average, for a 24 hour day.

I can post a list of the most efficient small AC refrigerators if you want. I tend to buy mine for $25 at yard sales used - so never got around to buying a new one. It's pretty much all about insulation anyway.

When it comes to compressor refrigerators - the ones with the German compressors are the most efficient. Most DC fridges use them but some Japanese units like Norcold do not. There are also 12 volt "non compressor" refrigerators that are cheaper and very inefficient.

One issue is inverters. Choose wisely. You cannot pick one just by the posted specs. Many cheap 1200 watt inverters run AC refrigerators with NO issues. Other more expensive 4000 watt inverters will NOT. The posted specs will not tell you. Best is to speak to someone that has used them and knows which ones work. The AIMs 1200 or 1500 watt mod-wave inverters work great and it's what many people with food concession carts use.

This one for $100 works fine BUT it comes with cooling fans that run all the time. If mounted inside an RV, then constant hum might bother you.

http://www.theinverterstore.com/1250-watt-power-inverter.html

This one is the "better" version with a thermally controlled fan-set that hardly ever runs the fans. Much nicer but $30 more. Price at $130 and usually free shipping.

http://www.theinverterstore.com/1250-watt-power-inverter-12-volt.html

By the way - there are many other good inverters out there. Also many bad ones. I'm only mentioned the AIMs because I KNOW they work well. The AIMs 1250 watt inverter is rated for a 3100 watt surge.

[zero]

check pplmotorhomes - I got a replacement for mine - they had one in stock with a good price.

as for going with non propane - unless you have quite a battery bank & way to charge those batteries I do not think it will work acceptably.

if you want to use ac or dc you pretty much need to be plugged into shore power or have the vehicle engine running.

you will also need a large inverter. the math can be found on line. it has to be big enough to start the compressor motor too.

I guess "large" is a relative term. A 1250 or 1500 watt (continuous rating) is what I regard as a "mid sized" inverter. and will run an AC refrigerator just fine. They cost $100 to $120 new. 12" X 8" X 3" and weigh 8 lbs. One of my RVs has a 5000 watt inverter (with 10,000 watt surge) and that I'd call somewhat big. My house and farm use a pair of 12,000 watt inverters and I'd call them "big."

[zero]

Some added info. I suspect most people don't want to mount a chest refrigerator in their RV. But here are the specs on my 5.8 cubic foot Sundanzer with the German Danfoss compressor. Runs on 12-24 volts DC. 37" wide by 26" deep by 35" tall. Uses 100 watt hours per day at 70 degrees F and used 240 watt hours per day at 90 degrees F. I find that to be amazing. I've had mine for 6 years now and love it. Only "problem" with it is when my neighbor shot it with a .2 rifle when chasing a woodchuck.

Note that 100 watt-hours per day is less then 1 amp @ 12 volts per hour, on average. Just one 60 lb. deep-cycle battery could run it for 8-9 days without a recharge.

[zero]

It think it is a very cool idea! I plan on getting a much smaller chest fridge that runs on 12v. No room in my rig for that monster sized fridge.

Chest refrigerators are always more efficient that stand-up units. The problem is there are not many compressor-type chest refrigerators around in small sizes.

Refrigeration has come a long way and sometimes I'm not so sure all the newer stuff is better over-all. We (collectively) are pretty spoiled from having fossil fuels to do our work. We still cut ice in the winter, store it in the ice hose and then use it in the summer and fall. It's a lot of physical work but it shows how long something can stay cool with proper insulation. Do it one winter and you come to realize how much work using fossil fuels prevents.

Here's some photos from winter when we scored the ice with mule power (to mark where to saw the ice). Then cut it with hand saws and pulled it onto skids and in the ice-house with horses. Did it in late February. Pack the ice in saw-dust and some will last through October.

One of my Toyota Chinooks came with an "ice box." Technically, they WERE called "refrigerators" back in the day -but I'm talking about a unit you have to stick ice in to stay cool.

[zero]

It think it is a very cool idea! I plan on getting a much smaller chest fridge that runs on 12v. No room in my rig for that monster sized fridge.

The guy asking about getting a "bigger" fridge in his Sunrader probably wants to upgrade his standard 4 cubic foot unit. On a scale or relativity, - using a 5.8 cubic foot chest refrigerator is not a huge leap. I assume it's around the size he's shooing for although I assume he wants a vertical (and more inefficient) unit.

Sundanzer also makes small chest refrigerators along with the larger ones that can be used with NO battery. The unit with no battery is kind of an interesting concept. NASA used it. It has permanent ice packs built into it. The ice-packs retain the cold when the sun is not shining.

SunDanzer BFR105 Battery Free Solar Refrigerator

Connect Direct to Solar Panels Without Batteries

Runs directly from a 130 watt 12 volt solar panel in most locations

The ice pack reduces the interior volume of the BFR105 to 105 liters or 3.7 cubic feet. Otherwise the exterior dimensions are the same as the SunDanzer DCF165 or DCR165.

Runs directly from a 130 watt 12 volt solar panel in most locations

Exterior size 36.8 x 26.2 x 34.5 inches LxWxH

Here's info on the smaller 1.8 cubic foot chest fridge that often sells for $550 if you shop around (not cheap).

Sundanzer Solar-Powered Refrigerator — 1.8 Cubic Ft., 24.5in.L x 27.5in.W x 36.5in.H

Requires a single 45W solar panel, 60Ah battery, 15A charge controller

[zero]

No room for even the small one in an 18' Sunrader. It would have to sit over the wheel well where the original fridge is installed and that would make it too tall for me to reach down into. I would need a step stool to use it. Plus it has a 100lb shipping weight!

I'm not recommending anyone put a Sundanzer in their RV. Just putting the info out there to show what can be done with a small amount of solar power. The big chest refrigerator weighs around 90 lbs. empty and the little one is around 60 lbs. empty. High efficiency refrigerators are heavy. A typical 4 cubic foot vertical model in the size that came standard in a Sunrader is often 160 lbs. A 9 cubic foot vertical aorund 215 lbs. So that makes the Sundanzers amazingly light on that reference scale.

I could of fit a Sundanzer chest refrigerator in my Chinook with some remodeling. Too expensive for me to be used part-time in an RV. My Toyota Chinook has dual refrigerators. The original Dometic three-way RM211 and another frige the same size but a Norcold 12 volt DC compressor model.

The guy who started this thread had a good idea if wanting something cheap. AC "dorm type" refrigerators from Walmart or Home Depot work great with inverters. Cheap and . . . if one dies while traveling - very easy to find a cheap replacement.

[Stevo]

Thanks everyone for you input. Yes I want a much larger fridge than what is there now and I don't want to spend a fortune. I understand that cold air falls which I assume is why chest fridges are supposed to be more efficient than stand-up fridges, but I question that with all the time spent with the lid open because you're having to dig endlessly through a pile of food makes them anymore efficient than a stand-up fridge. Like I said in my first post, after two months of using a chest fridge I have decided that I just don't like having all my stuff piled on top of each other so I'm going with a stand-up style with two doors that I'll probably have to fish through the back window.

I was thinking of something like this: http://tinyurl.com/bmtncyt

Its an Avanti fridge/freezer with 7.5 cubic feet of storage and only $310 at Walmart. 22.25" Deep X 21.5" Wide X 56.75" Tall

I don't know how accurate those energy guides are but it says it uses 311 kWh annually. I plan on having about 250 watts of solar panels with 3 to 4 batteries. What do you think?

[zero]

I haven't found Energy Star ratings to be very reliable in the past. But . . . they got caught fudging the numbers a few years ago and I assume they have to be more truthful now.

I've never run an AC frige over a 5 cubic foot size from an inverter so cannot say for sure how the Avanti would work out. I assume it will have an average amp draw at around 4 amps per hour @ 12 volts, 24 hours a day. 250 watts in solar power in my area of NY would barely provide 1 1/2 amps per hour @ 12 volts on average for a 24 hour day. Around 157 KWHs per year. If you are in a high sun area the panels can do better. Obviously the solar panels alone cannot do the job. If you're talking about stop and go RV use and camping - then the truck's alternator can pick up the slack. If you want to just park for extended periods of time - you need more solar power OR a better refrigerator. The Sundanzer I mentioned is MUCH more efficienct then the Avanti.

[Maineah]

One thing to think about, any fridge that is not built for an RV does not have a locking door and if you don't figure out a way to keep it closed you may end up with a bunch of cold food on your floor!

[zero]

I just checked the shipping weight for a Dometic 4 cu and is only 88lbs. I just removed my original Sunrader 4 cu fridge, helping to lift it up on a tailgate and 80 lbs seems spot on for its weight. No way does it weigh 160lbs.

Yes, and I never said it did. My comment was for a high-efficiency 4 cubic foot refrigerator and NOT an ineffiient Dometic. I.e. ,a frige the same size as what came standard in a Sunrader but NOT the same make and design. The Dometic has very little insultation in it. Seems many of the "complaint" posts in these forums have roots in reading-comprehension issues.

[zero]

One thing to think about, any fridge that is not built for an RV does not have a locking door and if you don't figure out a way to keep it closed you may end up with a bunch of cold food on your floor!

Yes and adding a door lock is easy. On all the AC refrigerators I've put into RVs, they have a 2nd door anyway. I use a 2nd door that has 1 1/2" foam for added insulation and locks into place.

[Maineah]

Thanks everyone for you input. Yes I want a much larger fridge than what is there now and I don't want to spend a fortune. I understand that cold air falls which I assume is why chest fridges are supposed to be more efficient than stand-up fridges, but I question that with all the time spent with the lid open because you're having to dig endlessly through a pile of food makes them anymore efficient than a stand-up fridge. Like I said in my first post, after two months of using a chest fridge I have decided that I just don't like having all my stuff piled on top of each other so I'm going with a stand-up style with two doors that I'll probably have to fish through the back window.

I was thinking of something like this: http://tinyurl.com/bmtncyt

Its an Avanti fridge/freezer with 7.5 cubic feet of storage and only $310 at Walmart. 22.25" Deep X 21.5" Wide X 56.75" Tall

I don't know how accurate those energy guides are but it says it uses 311 kWh annually. I plan on having about 250 watts of solar panels with 3 to 4 batteries. What do you think?

I agree with the chest fridge and where do you put it? Yes they most likely are more efficient but there are trade offs. The one you are looking at is pretty heavy and there is no spec. for power consumption (wattage) they also recommend a surge protector. It really would help if you could find out what the start current was so you could build some thing to handle the load with out going overboard.

[zero]

I agree with the chest fridge and where do you put it? Yes they most likely are more efficient but there are trade offs. The one you are looking at is pretty heavy and there is no spec. for power consumption (wattage) they also recommend a surge protector. It really would help if you could find out what the start current was so you could build some thing to handle the load with out going overboard.

Using a surge protector is kind of irrlevant when the refrigerator is used with an inverter. The Avanti is a bottom-of-the-line refrigerator is apt to have a high-start-draw compressor. More pricey refrigerators have low-start-draw compressors. Either way it's not an issue with the correct inverter and batteries.

I have a cheap 16 cubic foot AC refrigerator and it draws 7 amps at startup on AC and 75 amps on startup on 12 volts DC (via an inverter). I am sure the Avanti cannot use more then that and maybe less to start. A cheap 1250 watt mod-wave inverter like an AIMs can provide 25 amps for startup current at 120 VAC.

When it comes to big appliances and inverters - often the inverter itself is not the limiting factor. The voltage-drop from the batteries is the primary concern.

When you turn the key to start a Toyota truck - the starter motor draws high current (around 150 - 200 amps @ 9 volts). The battery voltage drops to 9 volts but since a so-called "12 volt" starter is really a 9 volt starter -all works fine.

With an inverter - things are different. It will be programmed to shut itself off if battery voltage drops below 10.5 volts DC. That is sometimes hard to prevent. To keep battery voltage above 10.5 volts means low draw is needed - or - multiple batteries. I have tested a pair of 120 AH batteries and 8 amps @ 120 VAC seems to be the max they can handle before dropping to 10.5 volts. Of course that will vary by battery make. Few "Walmart" style batteries will give any specs on amp-draw versus voltage drop. Some higher end batteries e.g. from Rolls-Surette, Trojan, and Outback do give those specs. Easy to check with a hand-held carbon-pile load tester though. Mine goes to 500 amps.

So in a nutshell - I am sure that Avanti 7.5 CF unit draws no more then 7 amps at "surge" start-up. A pair of 120 AH batteries hooked to a 1250 or 1500 watt inverter will work in that situation (just barely). Bigger batteries or three will make it work for sure.

My Sundanzer 5.8 cubic foot refrigerator has a low-start-draw Danfoss compressor. It draws 5 amps at 12 volts DC when starting. That is a huge difference when compared to many cheap AC refrigerators that need 60-70 amps at 12 volts to start.

[zero]

Some additional specs for anyone looking for "super" effiiency" and runnng a refrigerator with solar panels.

Danfoss is the #1 choice throughout the world for compressors in high-efficiency refrigerators and marine coolers. I'm not a salesman for them; it is just the way it is. The higher-end refrigertors use Danfoss and the cheaper ones (like Japanese Norcolds) use asian units.

Danfoss makes two different series in DC powered units.

The lower-priced compressor for small to medium refrigerators runs on 5 amps @ 12 volts and the start surge is 12 amps @ 12 volts.

The DC compressors made specifically for off-grid use with batteries and solar panels draws 2 amps when running and there is NO start surge. 2 amps running and 2 amps when starting.

Either unit is more efficient then any any AC refrigerator I know of and also much more effiient then any Travl'r or Dometic absorption when in electric mode.

Non-solar Danfoss - 5 amps @ 12 volts running (60 watts) and 12 amps @ 12 volts to start (144 watts).

Solar Danfoss - 2 amps when running or starting (24 watts)

Dometic 3 way when in DC electric mode - 8 amps @ 12 volts (96 watts) steady draw up to 15 amps @ 12 volts ( 180 watts)

Typical cheap AC regrigerator small to mid size run with an inverter off a 12 volt battery bank - 4-6 amps @ 12 volts to run (42-75 watts) and 16-75 amps @ 12 volts to start (192-900 watts). AC refrigerators vary a lot.

One additonal factor. Cheap modified wave inverters usually have much higher surge ratings then more expensive sine-wave inverters. But - cheap modified wave inverters do not start electric motors as well as sine-wave inverters and thusly need more power. So it's a trade-off. Some refrigerators with complex electronic controls won't work at all with mod-wave inverters. Modified-wave inverters do not make "conventional" AC current. In fact - you cannot even check voltage on one with a typcial volt-meter. You have to use a root-mean-square meter (RMS).

[Maineah]

Yes the 12V modern fridges are very nice and 2 1/2 times the price of a 120 volt fridge batteries not included.

[Stevo]

Hmmm, I thought a 250 watt panel with 3 to 4 batteries would be adequate provided everything else in the Sunrader was super energy efficient but now I'm having doubts. Ever since my ex father in laws nice motorhome started on fire (and then burned to the ground) while they were driving I've had issues with open flames on all the time which is why I've been hoping to stay away from having a propane fridge. Is it unreasonable to be concerned about having a pilot light on all the time?

It seems like there isn't much to a fridge/freezer as far as the stuff that makes it cold. What do you think about building my own DC fridge with freezer? I have the skills to build a box (was a cabinetmaker for years) with two doors and tons of insulation. Is that feasible? Has anyone heard of plans for doing this?

[Maineah]

Hmmm, I thought a 250 watt panel with 3 to 4 batteries would be adequate provided everything else in the Sunrader was super energy efficient but now I'm having doubts. Ever since my ex father in laws nice motorhome started on fire (and then burned to the ground) while they were driving I've had issues with open flames on all the time which is why I've been hoping to stay away from having a propane fridge. Is it unreasonable to be concerned about having a pilot light on all the time?

It seems like there isn't much to a fridge/freezer as far as the stuff that makes it cold. What do you think about building my own DC fridge with freezer? I have the skills to build a box (was a cabinetmaker for years) with two doors and tons of insulation. Is that feasible? Has anyone heard of plans for doing this?

Is that what caused the fire? I can say there is nothing that would make me want to give up my propane fridge for the complexity of more batteries solar panels inverters rewiring, bigger alternator etc, and carrying all the extra weight for something that only gets used in the summer (unless you live in it) to keep things cool frankly I would buy ice first if it wasn’t for the ice cream. If mine went toes up tomorrow I would buy another gas fridge.

[Maineah]

Yes of course you could build a fridge you'll need a compressor, dryer, condenser, refrigerant lines an evaporator, someone to charge it, thermostats, a place with air flow for the condenser, condenser fan, wiring and then you’ll have to power it. Alternatively you could use the A/C system for the cab but it would only cool with the engine running. I kinda hate to say this but the brand new motor homes still use gas fridges for a reason.

[Maineah]

some brand new motor homes use gas but many of them have onboard generators and use electric fridges. Many of the newer models offer solar panels as a standard option as it is very popular with the customers, those often have 12v fridges in them. The trend in motorhomes is now to go all electric and to get rid of the LP alltogether. But that trend is still pretty recent so LP is still being offered. With the current push towards carbon footprint reduction and alternative energy LP is on its way out. But it won't happen overnight. Within a decade though LP will likely become the option instead of the standard configuration. Of course the newer quiter, more efficient and "smart controller" generators are also playing a big push in this change away from LP.

My boyfriend is one of the designers of the smart controllers currently being used by Onoan for their generators that are standard in the upscale Winnebagos and other motorhomes.

There is a Camping world 10 miles from my house if they have one they have a hundred RV's not a single one has panels or DC fridges. I actually asked because I wanted to see some of the new ideals. My dream MH is a Via it is a $130,000 26’ class “A” MB Sprinter diesel it has a very nice Onan diesel generator and a propane fridge. Yes it will operate on ac while the generator is running. It's would be safe to say some high line RV have DC fridges with a roof full of solar panels and on demand generators. The technology is improving and the cost is going down and it will come however using a 6K generator to power a fridge right now is not very efficient or environmentally friendly. I guess my point still remains to retrofit a MH that’s all most 30 years old is not cost effective when for a bit less money you can buy a brand new propane fridge for just the cost of a DC unit alone and everything is already in place. If you are going to use a DC fridge a boat is a perfect place the bigger units and some small ones use sea water to cool the condensers making them extremely efficient.

[zero]

There is a Camping world 10 miles from my house if they have one they have a hundred RV's not a single one has panels or DC fridges.

When coming back from Kentucky a few weeks ago, we stopped at two huge RV dealers. Hundreds of large RVs on site. I saw many with 12 volt electric refrigerators. None with solar panels - but that is no surprise. I can't speak for your experience a Camping World but we saw plenty of DC refrigerators.

Not just a "modern" concept either. All the 1980s Winnebago LeSharos and Phasars had Norcold 12 volt electric refrigerators. I just stripped a 1973 Class A Winnebago that had a factory installed 6 cubic foot 12 volt DC compressor refrigerator. A friend of mine has a 1995 Ford-based Class B motorhome that also came new with a 12 volt DC compressor refrigerator. There are two Norcold 12 volt compressor refrigerators for sale today in my local Craigs List today for $150 each from older RVs.

Besides RVs, many sleeper-cabs in big-rig trucks have 12 volt DC refrigerators. "Truck-Fridge" is one of the most common.

http://www.truckfridge.com/

Marine coolers often have cooling units that are separate and cost a small fortune. Not what I'd consider cost-effective for an RV retrofit.

When it comes to solar panels and RVs - none of the factory intalls can fully sustain a parked RV. They are offered as "supplemental" and I assume not popular with cost-concious buyers. Some companies offer "free" 240 watt solar arrays if you buy a new RV. Maybe they don't add them on until the rig is sold.

RoadTrek has a no-propane "E-Trek" all-electric solar/electric RV available. Come with 6 AGM batteries, a 5000 watt inverter, 240 watts of solar power, etc. They claim the batteries can run the AC for 9 hours before a recharge is needed. They also claim that by starting the engine the batteries recharge in less then one hour and it uses less fuel then using a remote stand-alone genset. The RV is diesel powered and the hot water and heat also run off of diesel fuel. Cook stove is inductive-electric. The 250 amp alternator supplied 3500 watts of charging power when needed. Obviously the solar panels only offer supplemental power.

http://www.roadtrek.com/etrek.aspx

In regard to direct replacment in something like a Sunrader that came with a 4 cubic foot refrigerator? If someone wants electric and also the abiltiy to not have to level the RV for cooling - there are many direct-fit 12 volt refrigerators that sell new cheaper then the new absorption refrigerators.

[zero]

Hmmm, I thought a 250 watt panel with 3 to 4 batteries would be adequate provided everything else in the Sunrader was super energy efficient but now I'm having doubts.

A solar panel only produces its best power for 4-5 hours a day IF the sun shines. Once you spread out that 4-5 hours over a 24 hour day - you see the problem.

A 240 watt solar panel is . . . in essence . . . a 40 watt panel for a 24 hour day. That comes to around 2 amps per hour @ 12 volts, on average IF you live in a place that gets sun on a daily basis.

A 240 watt panel WILL run a high efficiency refrigerator made for solar use - like the Sundanzer I mentioned. In fact, here in my dark area of NY - a single 120 watt panel can do it as long as there is also a battery hooked in for ballast. A solar powered fridge must have ballast. Either electric (via a battery) or ice.

[zero]

Here is a writep-up someone else did about changing from propane to AC electric in an RV. Note that I have several and some of my RVs are 4WD and get taken off-road. All my AC refrigerators were bought used and I haven't had one fail yet.

Again - this is NOT my article. I just copied and pasted. This link has the story with photos:

https://sites.google.com/site/roadtrekersite/modifications/economy-refrigerator

Economy Refrigerator (Propane to AC electric)

I've never been a fan of ammonia absorption refrigerators found on most RVs. I've found them to be quite variable on how well they cool, some times freezing the food, other times barely able to get below 50 degrees - all at the sametemperature setting. You have to keep your RV parked relatively level for them to work at all. Their one asset, the ability to run on propane, is also a major hassle when traveling. I'm a firm believer in following the safety rules, which include turning off your propane at the tank when driving. This means your refrigerator must run on 12 volts while driving, and these fridges don't seem to work well on 12 volts. Also when you stop somewhere, you have to determine if you'll be gone long enough to make it worthwhile to turn the gas back on and re-light your refrigerator, versus draining your battery on 12 volts.

Lately, our refrigerator had stopped working on its 110 volt AC mode. I had plans to pull it out so I could fix it. After reading about someone else who had replaced their RV fridge with a standard 110 volt economy "dorm" refrigerator, I decided it would be fun to try a similar experiment, especially since I'd just installed an inverter and now had 110 volt power wherever I went. I realize that these regular cheapy refrigerators are not made to take the abuse of road travel, but I considered this a learning experience and experiment. So I went out and bought a Haier HSB03 2.7 cu. ft. refrigerator from Walmart for $90 so I could play.

Results so far:

I first did a battery drain test to see how long I could run the fridge off the inverter without charging the batteries. In 24 hours, the refrigerator drained the batteries about 30% to 40% (based on voltage measurements). I have two 92 amp hour AGM batteries. I figure I used about 70 amp hours in these 24 hours. This correlates well with current draw, which was about 7 to 8 amps when the compressor was running. The compressor ran about 30 to 40% of the time. Daytime temperatures in the van were about 86 to 90 degrees. Night-time low was 69. The refrigerator keep a temperature of 39 to 41 degrees based on the electronic refrigerator monitor we always use. By the way, I started this test when I first turned the fridge on and its inside temp was 84 degrees. It took about one hour to cool the fridge down from 84 degrees to 50 degrees. Since I doubt i will ever go more than 24 hours without driving the Roadtrek or having shore power, this 110 volt refrigerator concept works well for me from a power requirement point of view.

Next we tested the refrigerator on a three day camping trip with about 200 miles of driving. I was not sure if the refrigerator would stand up to the vibrations of driving, so we brought a backup cooler just in case. The refrigerator worked beautifully throughout the trip, maintaining a temperature between 39 and 41 degrees. The tiny freezer compartment was able to freeze ice cubes. The van alternator provides more than enough power to run the refrigerator and keep the batteries charged. When we got home, the batteries were fully charged. The refrigerator is very quiet, although you can hear some faint gurgling noise when the compressor runs and the coolant is running through the lines. Overall, it's a little quieter than our home refrigerator and noise was never an issue at night when we were sleeping.

Conclusion:

I'm still not sure how long this refrigerator will last with the road vibrations. I'm definitely sold on the concept of a standard compressor refrigerator instead of the inefficient ammonia absorption types. If this Haier breaks relatively soon, I will probably replace it with a 12 volt compressor refrigerator specifically designed for RVs and boats. These are twice as efficient (typically draw 3 to 4 amps) and are designed to take the bumps. They can be pricey however. If I can get a season or two out of this refrigerator, I think I'll just replace it with another cheapy model when the time comes. Too bad they didn't offer a 12 volt compressor refrigerator as an option when we bought the Roadtrek.

Update 2012:

Just completed a 6000 mile trip out to California. The refrigerator is still working nicely. The van engine keeps the batteries charged easily every day while driving. There's enough battery capacity to run the fridge overnight. We have run into a few instances where we have had to run the generator for an hour or so to recharge the batteries when we dry camp for over a day without any driving. This is a rare occurrence for us. I am so glad I converted to a regular refrigerator! It operates much much better than the original ammonia fridge and we rarely need to turn on our propane tank now.

[Maineah]

Heater, cooking and fridge total cost for the entire season around $25 worth of propane and I'm all most never in a camp ground. The propane coolers are not fast but starting a 12 volt fridge hot will take a lot of battery to get it to the point where it switch's off. I'm sure there were 12 volt fridges 20 years ago and I'm also sure they were not very good they still make Peltier Junction 12 volt fridges they work great for about a day and a half then you have a dead battery. Over the road trucks usually don't carry propane because of tunnel restrictions so a propane fridge is out so if they want to keep things cold that's about it they also have big batteries and big alternators and don't stay parked long..

[zero]

You are going to be faced with one other issus with using a modern standard type refrigerator in the winter time. They are not made to run in cold spaces,

That only applies to some of them. Many refrigerators and freezers work fine in unheated environments. The specs on a specific unit will tell if it needs to be in heated area or not. We have two freezers here that sit outside in an unheated room. Both came from Sears-Kenmore and both rated for use in any temp.

[zero]

Starting a 12 volt fridge hot will take a lot of battery to get it to the point where it switch's off. I'm sure there were 12 volt fridges 20 years ago and I'm also sure they were not very good

The big refrigerator I pulled out of a 1973 draws 5 amps @ 12 volts. That's not excessive. The main issue is insulation, not the amp-draw. I.e. how much it has to run, not how much it draws when it runs. If my math is correct "20 years ago" was 1993. I have a pair of Norcold 2 cubic foot 12 volt refrigerators here built in 1984 and 1986. It's what the Winnebago Lesharos and Phasars came with. Either draws 2.5-3 amps when running. The newest TruckFridge or newest Vitrifrigo C60i draw exactly the same when running. Nothing has changed except some newer models are getting added insulation. They all use around 22 amp-hours per day at 70F with the standard 1" of insulation and less when more insulation is added.

In regard to excessive power used when staring with a warm refrigerator? A minor issue as I see it but -who the heck gets ready for travel or camping and loads their refrigerator with warm food? I know we don't. We take cold food from our house frige and stick it into the camper when we go.

[zero]

A comment on AC refrigerators and being used with inverters in RVs. I just fixed a big Norcold regrigerator in my neighbor's 1980 Winnebago. It's a big refrigerator. Measures 52" tall by 25" wide by 27" deep. Norcold model DE728 "dual voltage" refrigerator. He runs it on DC all the time except when at a campground that has AC power. To my surprise after studying it a bit - it is basically an AC refrigerator with an built-in AC to DC inverter. It draws 8 amps @ 12 volts when run off a battery and cycled about 1/4 of the time when I was working on it. That means with the inverter - this big refrigerator draws 8 amps @ 12 volts for 6 hours a day, i.e. 48 amp-hours a day.

So, I learned something new. My smaller 1986 Norcold DC refrigerator has a DC compressor, unlike the bigger Norcold in the Winnebago that has an on-board inverter and an AC compressor.

[zero]

it is basically an AC refrigerator with an built-in AC to DC inverter.

Correction. I typed that "back-assw*rd.' Should read DC to AC inverter.

[Stevo]

I found a non-working 10 year old Norcold DE-461 AC/DC fridge (7.5 cu ft) that I could buy used for $150. I sent the seller some questions and am waiting to hear back. If there is yellow stuff around the cooling unit then forget it cuz that means an ammonia leak that will require a new cooling unit which costs $1000...AARGH! Its replacement, the Norcold DE-0061, is $1300 new but I don't want to spend anywhere close to that on a fridge.

So then I called the Avanti company about their 7.5 cubic foot AC apartment fridge/freezer at Walmart for $310 and they said...

-Startup: 8.6 amps (935 watts)

-Running: 1.7 amps (110 watts)

If I added major foam insulation to it and wasn't the type that stands there gazing into an open fridge, how much solar and batteries do you think I'd need in a warm climate to run this thing?

[zero]

I found a non-working 10 year old Norcold DE-461 AC/DC fridge (7.5 cu ft) that I could buy used for $150. I sent the seller some questions and am waiting to hear back. If there is yellow stuff around the cooling unit then forget it cuz that means an ammonia leak that will require a new cooling unit which costs $1000...AARGH! Its replacement, the Norcold DE-0061, is $1300 new but I don't want to spend anywhere close to that on a fridge.

So then I called the Avanti company about their 7.5 cubic foot AC apartment fridge/freezer at Walmart for $310 and they said...

-Startup: 8.6 amps (935 watts)

-Running: 1.7 amps (110 watts)

If I added major foam insulation to it and wasn't the type that stands there gazing into an open fridge, how much solar and batteries do you think I'd need in a warm climate to run this thing?

That Norcold you mention (DE461) is an AC refrigerator with a built-in inverter to let it run on DC. It is a compressor refrigerator that probably uses R134A refrigerant, just as cars and trucks to since ca. 1995. Some of the older Norcolds have R12 in them. NO ammonia inside.

With the Avanti - the start-up current is not an issue in regard to run time on batteries. The running amps will be around 12 amps @ 12 volts DC when running an inverter. (3 amps @ 12 volts per hour for a full day average). In 70 F weather it will probably cycle 1/4 the time and at 90F it will cycle 1/2 the time. If you add insulation, it will run much less. So - as is with the factory 1" or 1 1/2" of insulation - it will use 72 amp-hours @ 12 volts at 70F for a full day and 142 amp-hours @ 12 volts at 90F for a full day. A typical BCI type 27 or 29 deep cycle battery will run it at 70F for around 10 hours (if only run down to half-charged and not dead). So, two batteries can run it for 20 hours (only run to half-charged and not dead).

Much depends on how you are using your RV. If you run it once a day and have a decent sized alternator - it will charge up the batteries pretty fast. If you do NOT run it - and want to run totally on solar power? That would be very difficult. A 120 watt solar panel puts out 15- 25 amp-hours in a day unless you live in a very sunny area (about 1 amp per hour for a full day average). In a very bright area it is possible for a 120 watt solar panel to put out 36 amp-hours in a day. With the 25 amp-hour figure, you'd need at least three 120 watt panels. That's what is so nice about the Sundanzer 5.8 cubic foot refrigerator. It uses less then 1 amp per hour @ 12 volts, whereas this Norcold will use 3-4 amps @ 12 volts per hour, on average. Much of that efficiency is due to it being a chest model and having 5"-6" of insulation intead of just 1"to 1 1/2" like the Norcold. The compressor is also more efficient.