rv frig 110V to 12V

[sugermc]

Could some one help, thinking od putting a 110V frig in Scamp but would like to run it on a battery while traveling to destination, then at site just run off the electricity
Questions 1) Has ANYONE done this? I just wanted to use those small dorm type frig
2) and it it's possible do you use a "invertor" (sp?) or a convertor - that redi-kilowatt stuff sometimes throws me
3) And can anyone tell me how long the bettery would last? we have a deep cell marine type

thanks for any info suger

[Byron Kinnaman]

Originally Posted by sugermc

Could some one help, thinking od putting a 110V frig in Scamp but would like to run it on a battery while traveling to destination, then at site just run off the electricity
Questions 1) Has ANYONE done this? I just wanted to use those small dorm type frig
2) and it it's possible do you use a "invertor" (sp?) or a convertor - that redi-kilowatt stuff sometimes throws me
3) And can anyone tell me how long the bettery would last? we have a deep cell marine type

thanks for any info suger

It can be done and has been done. First, unless you're going to be traveling for a couple days in hot weather you won't need to run the refrigerator while traveling. A few hours won't hurt.
Things to consider when making any part of your Scamp all electric. First you've lock yourself into needing to be at a place with at least electric hook-ups. If this something you can live, then you should be ok, until you have a long term power outage.
Running an inverter (not converter) to keep the refrigerator while traveling depends on the tow vehicle and it's ability to provide the required electricity. To determine how much is needed from the tow vehicle look at how much is required by the fridge. Then multiply that times 10 to get approximately how much the tow and house battery would have to supply.
The house battery won't last very long, but you need the above information first. How much current is the fridge you want to going to need?

[honda03842]

Our first trailer had a failed fridge and we replaced it with a 4.4 cubic foot dorm fridge. It worked extremely well providing a bigger volume than the dometic in virtually the same space. The following is from memory.

We added a 1200 watt inverter to run the fridge ($59 at the Black and Decker outlet store.) My recollection is that the fridge only drew 400 watts and ran for a couple of minutes every 15 minutes or so.

We usually did not run the fridge while driving unless we were driving more than 3 or 4 hours, rare for us, or if it was an extremely hot day. The single battery seemed to be good for about 12 hours. We initially had the ability to charge the battery from the tow vehicle while driving. In our last year we had a 120 watt solar panel on the roof.

The only mod we had to make to the fridge was the addition of a large O-ring to keep the door closed while driving.

If you're a person who typically parks at a serviced sites there are no real issues.

Norm

[Byron Kinnaman]

Originally Posted by honda03842

Our first trailer had a failed fridge and we replaced it with a 4.4 cubic foot dorm fridge. It worked extremely well providing a bigger volume than the dometic in virtually the same space. The following is from memory.

We added a 1200 watt inverter to run the fridge ($59 at the Black and Decker outlet store.) My recollection is that the fridge only drew 400 watts and ran for a couple of minutes every 15 minutes or so.

We usually did not run the fridge while driving unless we were driving more than 3 or 4 hours, rare for us, or if it was an extremely hot day. The single battery seemed to be good for about 12 hours. We initially had the ability to charge the battery from the tow vehicle while driving. In our last year we had a 120 watt solar panel on the roof.

The only mod we had to make to the fridge was the addition of a large O-ring to keep the door closed while driving.

If you're a person who typically parks at a serviced sites there are no real issues.

Norm

You have more than just battery and inverter capabilities to concern yourself with. The ability of the wiring to handle the current while the fridge is running is very important. Your 400 Watt fridge would draw 33 Amps while running if in fact it was 400 Watts. Most Scamp wiring is designed to handle only 20 amps max.
This is a recipe for a trailer fire.

[honda03842]

Originally Posted by Byron Kinnaman

You have more than just battery and inverter capabilities to concern yourself with. The ability of the wiring to handle the current while the fridge is running is very important. Your 400 Watt fridge would draw 33 Amps while running if in fact it was 400 Watts. Most Scamp wiring is designed to handle only 20 amps max.
This is a recipe for a trailer fire.

Sugar MC and Byron,

There are no current overload issues in a proper Inverter installation. A description of our installation follows.

We located our Inverter, a device that converts 12 volt DC to 110 volt AC inside the trailer but near the battery. Our 1200 watt Inverter in our Scamp is located under the front couch beside our converter.

Our Inverter came with two short heavy cables that run from the battery to the Inverter to supply the Inverter with battery power. These two cables run thru the couch's floor directly to the battery terminals. This is the only place 33 amps flows. The Inverter and the cables are designed for this level of current flow.

Also note that there is only 33 amps in those cables when the refrigerator is running the compressor.

From the inverter to the refrigerator, only 4 amps of 110 volts AC flows. This is definitely within the design ability of the Scamp's wiring.

In summation, the 33 amps is only running between the battery and the Inverter. From the Inverter to the refridgerator you are only running 4 amps of 110 volts AC, less than runs in your Air Conditioning wiring or your wife's hair dryer.

The only precautions are these. 1. Before you connect up to shore AC be sure to turn off your Inverter. You do not want your Inverter and Shore AC to be in conflict. 2. Make sure you have good connections to the battery and Inverter and use the power cable provided with the Inverter.

As I said in a previous post, the electric fridge will maintain temps for a considerable period. When we installed our AC fridge we put foam insulation in the gaps between the walls and fridge to improve it's ability. As well when plugged into AC, the night before leaving we lower the temp to make it a little colder to being a drive.

There are a few more tips to using an Inverter well. If you want more info I can provide follow up info. I will say the inverter is particularly handy for making coffee in the morning or watching TV at night. In actuality we always carry two levels of converters, a 1200 watt device that can run everything in our trailer, except the Air Conditioner and a 100 watt device that can run the TV and charge the computer and phones.

We also carry a 100 watt inverter, cigarette lighter type, in our car to charge our cell phones while driving and sometimes our computer.

I just checked the Energy Star rating on a 4.5 cubic foot GE compact refrigerator because my previous post was from memory. On average a compact fridge draws less than 4 amps of battery current per hour for the Inverter.

In closing we installed in AC fridge because our 3 way was almost 30 years old and had failed. We planned to own the trailer for only a year to go to Labrador. Certainly a three way has broader application, covering more situations. In closing we used that AC fridge for 3 years without a single negative issue.

Hope this clarifies the situation.

Norm

[sugermc]

Hey Norm, great info, I have a real good idea of how this works now. For the record,
I installed a new electriclal box with two 15 amp circuit breakers, and ran 12-2 wire to the oulets, so I figure I am good to go, one circuit dedicated to fridge and the other outlet is for micro & coffee, and a reading light.
Also, boondocking was hip when I was broke and in my 20's, My husband likes showers, coffee and a fan if its hot (we have no AC). I am glad to find out that stuff will stay on a 5/6 hr drive. I am trying to take advice from others and not take those monster drives, find a place, park and day trip.
AS for charging battery from the tow vehicle, we have a 2010 ford sport trac and it have a power port in the bed, by the tailgate, in addition to the port for the trailer lights. so do you take power from the trailer lights part or run a separate thing to this other poer port? and does this run to the invertor/convertor?
I did buy a little circuit board thing from west marine that has switches to power up, I guess i was planning an outside light and maybe some type of reading 12v light, really I am still just figuring out what I should have.
This frig thing, well the last one we had, was a dometic 3-way and after cleaning the orvice(sp) and replaceing the fitting, did a test drive with the lp before installing in trailer, and the darn thing caught on fire!! That's why I was leaning toward and electric with a 12v back-up - gas spooked me, though all my friends use it in their trailers. Just my luck to get spooked
I should maybe post some updated pic's of the work, but anyway I have rigid insulation already installed where the fridge was to be placed.
thanks for the help, I may need more
suger

[cpaharley2008]

If your trailer wire is 7 pin then one of the pin's is a charge wire that will charge your battery, if it is a 4 pin then you will have to find another source. If it is 7 pin, check to see if the power wire is hooked up, sometimes when installing a wiring harness they power wire is forgotten. I had that on one of my vehicles, my battery kept going down, I went to a rv place and they had to run a power wire to my harness, all was well after that.

[sugermc]

well thank you for that info, partner. Now can you tell us, how does a battery from the vehicle, charge the battery in the trailer & can you run the fridge while that is happening or does it need to be disconected?
The alternator of the tow vehicle must play into this right?

here is a pic of the space I wish to put the fridge




well I forgot how to post a pic, maybe latter suger

[cpaharley2008]

If it is wired properly, a 7 pin harness will have 7 connectors, for tail lights,brake lights,turn signals,back up lights, charging line, and 2 others. This will allow your tow vehicle alternator to charge your battery in the trailer while connected and with motor running. This will allow your 12v refer to run. BUT, and this is a big but, when you turn off the motor, anything in the trailer will start to drain your car battery as well as your trailer battery. So you have to unplug when you stop for any length of time so that your car battery does not drain. You can leave the refer on while enroute but remember to unplug from the car when you stop. Then the battery in the trailer will operate the refer.

[sugermc]

Originally Posted by cpaharley2008

If it is wired properly, a 7 pin harness will have 7 connectors, for tail lights,brake lights,turn signals,back up lights, charging line, and 2 others. This will allow your tow vehicle alternator to charge your battery in the trailer while connected and with motor running. This will allow your 12v refer to run. BUT, and this is a big but, when you turn off the motor, anything in the trailer will start to drain your car battery as well as your trailer battery. So you have to unplug when you stop for any length of time so that your car battery does not drain. You can leave the refer on while enroute but remember to unplug from the car when you stop. Then the battery in the trailer will operate the refer.

thanks for the heads up on the charging/battery operation, I did fumble around and poated the pic, but when I hit upload the little icon was not in the place where I wished the pic to be. And this upload thing seems different from the last time I posted, has it changed?

well I am just a dinosaur on this computer stuff, heck the local kids made fun of my dictionary because it did not have "internet" listed, it was published in 1965, and belonged to an old friend

[cpaharley2008]

Is that refer a 12v or 110 volt? Everything I have told you assumed a 12v refer. If it's 110 then you will have to do what Norm said up above and install an inverter. My refer is a 12v.
I also see several extension cords, you lose a lot of power, particularly when running an inverter off 12 volts, in wire length. Plug your refer directly into your inverter.

[sugermc]

Originally Posted by cpaharley2008

Is that refer a 12v or 110 volt? Everything I have told you assumed a 12v refer. If it's 110 then you will have to do what Norm said up above and install an inverter. My refer is a 12v.

the one inthe pic is one of those colemans with a power plug you plug into a lighter, but I want to use a 110V, they are all over the place and cheep. So If I could lay this out right with inverter and wiring, it would be cheeper that those expensive rv refrig's

[Mark12]

Originally Posted by honda03842

Sugar MC and Byron,

There are no current overload issues in a proper Inverter installation. A description of our installation follows.
... <snip> ...
In closing we used that AC fridge for 3 years without a single negative issue.

Norm

Norm, thanks for that detailed description (which I just abreviated) of your using an inverter with an AC fridge. I was wondering how my new (to me) Scamp's air-conditioner will behave on inverter power. And I had heard some negative comments about how inverters can affect AC appliances.

I camp at my farm because there is no house, but I have solar power with an inverter to power the lights and tools in the barn. I think it will be safe to assume that the air-conditioner functions like a large fridge (i.e. a compressor pump and a fan), so if your fridge didn't mind inverter AC my air-conditioner shouldn't mind either.

I have a small generator in case the inverter wouldn't work, but hopefully I can just park the camper near the barn, and plug into that when I need the air-conditioning.

Thanks!

Mark

[cpaharley2008]

You can not operate a/c off an inverter. Inverters are very inefficient, it is far better to purchase a refer designed to operate off 12v, here is one for $200
Avanti AC/DC Superconductor Refrigerator, Model# SHP1712SDC | 12-Volt Accessories | Northern Tool + Equipment

[cpaharley2008]

The above one is an ambient refer, it will keep foods cold up to a certain temperature, I do not think they will work in high temperatures. A true refer/freezer 12v model is about double that price here is one
FP430 Compact EdgeStar Portable Refrigerator Freezer
these are real nice and can be resold when no longer needed because they hold their value.

[sugermc]

Originally Posted by cpaharley2008

You can not operate a/c off an inverter. Inverters are very inefficient, it is far better to purchase a refer designed to operate off 12v, here is one for $200
Avanti AC/DC Superconductor Refrigerator, Model# SHP1712SDC | 12-Volt Accessories | Northern Tool + Equipment

we have a Northern tool here in knoxville (aka knox-vegus to us hicks outside of the big town). thanks I am going to check it out

[honda03842]

Mark,

A major difference between an Air Conditioner and a Refrigerator is that the refrigerator runs relatively infrequently when on while Air Conditioners runs continuously when on.

The Air Conditioner would quickly discharge your battery even if the Inverter could handle the Air Conditioner.

Inverters are very good at taking 12 volts and turning it into 110 volts AC, The unfortunate part is that for every amp of AC it takes about 10 amps of 12 volts. A small Air Conditioner draws about 5 amps of AC meaning the battery would have to continuously supply 50 amps.

Our coffee pot draws about 5 amps of 110 volts AC like a small air conditioner. We often run it off the Inverter. The good part is that it takes less than 10 minutes to make coffee.

In conclusion, your best bet is to plug into your barn. An AC outlet is better than a generator for air conditioning if you have access.

Norm

[Bill K]

Sorry Norm, but you are very confused.

The fan on a AC may run all the time but the compressor cycles just like a fridge.

Bill K

Originally Posted by honda03842

Mark,

A major difference between an Air Conditioner and a Refrigerator is that the refrigerator runs relatively infrequently when on while Air Conditioners runs continuously when on.

The Air Conditioner would quickly discharge your battery even if the Inverter could handle the Air Conditioner.

Inverters are very good at taking 12 volts and turning it into 110 volts AC, The unfortunate part is that for every amp of AC it takes about 10 amps of 12 volts. A small Air Conditioner draws about 5 amps of AC meaning the battery would have to continuously supply 50 amps.

Our coffee pot draws about 5 amps of 110 volts AC like a small air conditioner. We often run it off the Inverter. The good part is that it takes less than 10 minutes to make coffee.

In conclusion, your best bet is to plug into your barn. An AC outlet is better than a generator for air conditioning if you have access.

Norm

[sugermc]

so norm are you saying that I could run a 110V fridge (dorm size, 20" x 20") off the battery and not run/drain it down quickly?
As I understand this conversation to date

If Ihad a 110 V refrig, plug into the 12V system, and its taking power, while driving, its charging the battery off the alternator, thru the 7 pin plug. Then when I reach the destination I can plug up to the 110 on site.
If this is correct I could run/drive a good 6 hrs and have cold stuff and a battery relatively charged up. Is this correct? thanks suger

[honda03842]

Originally Posted by sugermc

so norm are you saying that I could run a 110V fridge (dorm size, 20" x 20") off the battery and not run/drain it down quickly?
As I understand this conversation to date

If I had a 110 V refrig, plug into the 12V system, and its taking power, while driving, its charging the battery off the alternator, thru the 7 pin plug. Then when I reach the destination I can plug up to the 110 on site.
If this is correct I could run/drive a good 6 hrs and have cold stuff and a battery relatively charged up. Is this correct? thanks suger

First, an AC fridge only runs on AC so there needs to be an Inverter between the fridge and battery.

Second, when we're plugged in the night before we turn the fridge down to a colder temperature.

Third, the fridge stays at a reasonable temperature for about four hours if you do nothing except keep the door tightly closed. Most of the time we do not run the fridge while driving, even our three way.

Keeping the door closed is an issue because there not designed for travel. To solve this we put a small screw in the top of the door and a screw (hook) in the wall above it. Between these two we have a large O-ring.

Fourth, we had a type 24 battery and it easily met your 6 hour requirement. we never really worried about it because once we started driving we turned on the 12 volts from the car to the trailers battery.

If you live any where near me (Hampton, NH) I'd be happy to help you with the project.

My fridge is 32x20x20.

Hope this helps

Norm