Swap 2 way fridge to compressor fridge

[IsleDog]

As the title states, we are looking at swapping out our 120v/LP fridge for a compressor fridge. we currently have a Norcold 305/306 that has some wildly inconsistent temps and we absolutely hate its design and small 2.7 cu ft of space. yes we tried fans to remove the heat behind the fridge and a fan inside.

we have decided to remove it and cap off the gas line and replace the unit with a 120v 3.1 cu ft compressor fridge and run it full time on a 12v inverter. we do not boondock and have no plans in the future of doing so. link of the fridge in consideration below.

how well do residential type fridges handle road vibrations while towing? some of our travel days are 6-8 hours.

is there any real advantage with going to a 12v compressor fridge vs a 120v fridge on an inverter?

anything else that we are not thinking of with this project?

All thoughts and ideas are welcome!

https://www.walmart.com/ip/Galanz-3-...E&gclsrc=aw.ds

[Flybob]

Assume that you have no plans for camping off the grid.

[NMWildcat]

The only question I have is why run it on an inverter all the time? I understand when you are traveling, but when at full hookups I would want it run directly from a 120v plug. You could use a transfer switch, but in your case it might be just as easy to move the fridge plug from one to another. I would think running it fulltime on the inverter would put extra stress on the battery charging system.
As far as 120v fridges holding up to RV life, I would not be concerned. They are shoving 120v fridges in RVs all the time and I know most if them are not specially designed for RV use. And besides, if it does fail for some reason, it won't be a big deal, physically or financially, to replace it.

[IsleDog]

Originally Posted by Flybob

Assume that you have no plans for camping off the grid.

correct, we dont have any plans for off grid camping. we do have an inverter generator we can take if needed.

[Rhumblefish]

That's a nice low price on a fridge. But making 120v out of 12v is fairly inefficient way to generate 12v (as low as 75%). If you had a native 12v fridge (more expensive), your batteries might thank you, power-wise (for travel day). A solar maintainer (simple 190w setup) would also help collect energy and keep your batteries charged (in addition to the small amount of 12v your trailer is getting from the seven pin) while on the road. Our 12v compressor fridge is a champ, and has dealt with a year of on-road without a hiccup. We do boondock, and built up our solar and battery bank to deal accordingly. It's not cheap up front, but it's (1) more affordable if you look at long term and cost differentials btw Evap and 12v architecture AND Lead acid/AGM vs LiFePo in the long run. Our rig has proven to be faultless for our use.

Good reminder that everyone has their own unique power needs and usage profile - it's really important to understand how it all will work together. Not boondocking will make your requirements easier to meet, though some battery+solar might make an overnight on the side of the road or the Cracker Barrel parking lot more manageable. Likewise, a small inverter generator could also meet needs for impromptu overnights.

Since you're going from power pole to power pole (and potentially storing in between), it's likely you can get away without a significant investment.

Just my .02, hope this helps!

[IsleDog]

Originally Posted by NMWildcat

The only question I have is why run it on an inverter all the time? I understand when you are traveling, but when at full hookups I would want it run directly from a 120v plug. You could use a transfer switch, but in your case it might be just as easy to move the fridge plug from one to another. I would think running it fulltime on the inverter would put extra stress on the battery charging system.
As far as 120v fridges holding up to RV life, I would not be concerned. They are shoving 120v fridges in RVs all the time and I know most if them are not specially designed for RV use. And besides, if it does fail for some reason, it won't be a big deal, physically or financially, to replace it.

We certainly could swap it over from inverter to shore power. If we forget to swap it over or we get lazy it may run on the inverter while on shore power. good to know that a residential unit will hold up!

[DougW]

Originally Posted by IsleDog

We certainly could swap it over from inverter to shore power. If we forget to swap it over or we get lazy it may run on the inverter while on shore power. good to know that a residential unit will hold up!

Many of the inverters designed for RV use will automatically switch from battery to shore power whenever shore power is connected. We had one like that in our motor home and it worked flawlessly.

[IsleDog]

Originally Posted by DougW

Many of the inverters designed for RV use will automatically switch from battery to shore power whenever shore power is connected. We had one like that in our motor home and it worked flawlessly.

great idea! do you or anyone else have any models that I can take a look at? Im not sure where to even start here. the fridge draws .8 amps, so about 100 watts. power requirements are pretty small. we are not planning on powering anything else on this inverter.

[Larry-NC]

Originally Posted by DougW

Many of the inverters designed for RV use will automatically switch from battery to shore power whenever shore power is connected. We had one like that in our motor home and it worked flawlessly.

The key word for this function is "Transfer switch." You would look for an inverter with a built-in (internal) transfer switch. Do you know how many watts the candidate refrigerator needs. (Maybe allow an extra 50% for a short current surge at startup.)

This one, for example is a 1000 watt pure sine wave inverter with a built-in transfer switch.

Don't take this as a recommendation. It's the first one I found. There may be better and cheaper ones available.

[DougW]

Originally Posted by IsleDog

great idea! do you or anyone else have any models that I can take a look at? Im not sure where to even start here. the fridge draws .8 amps, so about 100 watts. power requirements are pretty small. we are not planning on powering anything else on this inverter.

The one we had was made by Xantrex. I have heard Renogy is a company that also makes electrical system items for RV’s. Progressive Dynamics also make some, they seem to all be in the 1,000 watt plus size range.

[rickthor]

We switched to residential refrigerator in our class A sometime ago without any issues. The inverter has an automatic switch that easily recognizes when to switch to shore power and back when we are motoring down the highway. As for durability of rv life on the refrigerator, don’t loose any sleep over it.

[jbflag21ds]

Originally Posted by DougW

Many of the inverters designed for RV use will automatically switch from battery to shore power whenever shore power is connected. We had one like that in our motor home and it worked flawlessly.

Originally Posted by IsleDog

great idea! do you or anyone else have any models that I can take a look at? Im not sure where to even start here. the fridge draws .8 amps, so about 100 watts. power requirements are pretty small. we are not planning on powering anything else on this inverter.

Most of them are called "inverter chargers" and need to be hooked up to batteries and two sides of the AC system. One to get power and pass it through via an internal ATS and one side to the outlet end. They are for sure more difficult to install due to the AC input issue.

You can use a regular inverter and add an ATS between the inverter and the outlet for the fridge. You'll have to remember to turn off the inverter as just having it on even if you have shore power will use up battery (though the RV's converter should be charging faster than the inverter is consuming at "idle")

[IsleDog]

Originally Posted by Larry-NC

The key word for this function is "Transfer switch." You would look for an inverter with a built-in (internal) transfer switch. Do you know how many watts the candidate refrigerator needs. (Maybe allow an extra 50% for a short current surge at startup.)

This one, for example is a 1000 watt pure sine wave inverter with a built-in transfer switch.

Don't take this as a recommendation. It's the first one I found. There may be better and cheaper ones available.

the fridge uses .8 amps / 96 watts at running power.

[Larry-NC]

Originally Posted by IsleDog

the fridge uses .8 amps / 96 watts at running power.

Then a 200 or 250 watt inverter ought to be able to handle it, including startup surge. Do the specs disclose the startup current (not running)?

A quick search did not reveal any inverters at that power level that had built-in transfer switches. Maybe a more thorough search would find one.

[IsleDog]

Originally Posted by Larry-NC

Then a 200 or 250 watt inverter ought to be able to handle it, including startup surge. Do the specs disclose the startup current (not running)?

A quick search did not reveal any inverters at that power level that had built-in transfer switches. Maybe a more thorough search would find one.

I currently have a Samlex 300/600 pure sine wave inverter that i was hoping to use. we are not too terribly worried about a transfer switch as we can unplug from the inverter and plug into the existing 120v power plug when on shore power.

I wish I had the startup surge power rating from the compressor, that would make this process a lot easier. we were hoping to (and did) get some ideas if this project would even be possible before sinking any money into it.

[TitanMike]

Originally Posted by Larry-NC

Then a 200 or 250 watt inverter ought to be able to handle it, including startup surge. Do the specs disclose the startup current (not running)?



A quick search did not reveal any inverters at that power level that had built-in transfer switches. Maybe a more thorough search would find one.

I have an outside kitchen fridge with same specs. I tried a 300w TSW inverter to no avail. Seems that the inrush is over 7 times running current. I just installed a 1Kw TSW inverter costing me $144.

[ESGWheel]

Originally Posted by IsleDog

I wish I had the startup surge power rating from the compressor, that would make this process a lot easier.

You are correct; you need to know the startup current draw > it will be significantly more then the 0.9 amps during running. Plug in ‘Digital Power Monitor Meters’ are readily available and fairly inexpensive. Look for one that holds the peak value.

[ESGWheel]

Also here is a comprehensive video on the various alternatives and their electric consumption, etc.

https://www.youtube.com/watch?v=RwHU_NY0Auo&t=425s

[BT3927]

Typical starting current for induction motors is about 6 times running current as a rule of thumb. Some motors might be a little more, some a little less but this is a good approximation. This could be specified for a compressor motor as Locked Rotor Amps (LRA).

[RFSims]

https://www.recpro.com/rv-refrigerat...ainless-steel/

No need for inverter. Tow vehicle will charge battery while underway, at least mine does in my Rockwood Signature with 12V fridge. Probably less cost than 120V fridge and inverter with a transfer switch. Keep it simple.