Like many RVers I decided to replace my troublesome rv fridge with a residential. I have read a lot of posts here and other places about doing so and battery life when camping without shore power. Some say you need a large bank and solar and a few said don't worry about it. We camp 1-2 weekends per year without shore power and many other times with power so adding a lot of capability for the couple of times was not high on my list but I wanted to see if it is doable with 2 batteries and a cheap harbor freight inverter. So I purchased a $45.00 inverter and set about finding out. I will be traveling with the fridge running so the TV will keep it charged easily during those times. I had an old golf cart battery in my basement for a few years so I charged it overnight (it was dead) not expecting much from it but it is still good.... Wow!!!!I set up everything on my workbench and started testing.The fridge was NOT cooled down priorI started after the charger was disconnected for 12 hrs and the battery voltage was 13.16vHooked up the inverter and turned the fridge on. Starting amps measured on the 12v side was 75a for 1 second then it settled to 10a while the compressor was running. Running voltage settled at 12.91vAfter 2 hours I checked and the open circuit voltage was 12.82 and dropped and settled to 12.52 while it was runningAfter 6 hours the open circuit voltage was 12.62 and running voltage was 12.50Remember this is from a battery of unknown life left, shockingly it performed so well that it will go back into the camper to augment the 2 that are already in thereI learned 2 things1 I have a good battery to add (ford think cart battery)2 My fridge will definitely run all night on 2 or 3 batteries with easeSpecs:Fridge 6.0a starting / 1.0 running Inverter HF 750w continuous / 1500w surgeBattery. 1 worn out golf cart batteryCharger. Cheap brand

Some friends just bought a Pinnacle with the residential fridge. They get 1 day out of a single 12v deep cycle battery. They weren't using many other loads so I think this is a good number.Jim

Is there not an issue regarding a third battery to the system that may not be compatible with the two already there? Do they not need to be in sync regarding their individual capabilities? For example, would pairing a new and an old battery not result in the demise of the new battery?I am also curious as to the size of the "residential" refer you are using. Vic

I don't think there is an issue with adding a third battery as long as it is in good shape. Batteries are not smart and really don't care about mixing and matching, I will test it again when I'm done after I let it sit untouched for a week. Not positive I will be adding it until I do that test. The fridge is a Black and Decker 4.5 cu/ft apartment fridge. I have had it for 2 years now as a spare, it is about 18in shorter than the Dometic it is replacing. Looking forward to the added shelf above the fridge. Ideally a taller fridge would be better and when I get one I probably will do another install, but I have this and the fridge part is larger than the Dometic fridge but the freezer is tiny. Since it can hold my ice cream its large enough for me.Doing the stress test today since I am home on kid patrol all day. Charged battery last night and have been running the fridge for 8 hours nowOpen circuit voltage is 12.52 and running is 12.40Let's see what it looks like after 10 hours......I will stop when the OCV is 12.0v

Adam H wrote:I don't think there is an issue with adding a third battery as long as it is in good shape. Batteries are not smart and really don't care about mixing and matching, I will test it again when I'm done after I let it sit untouched for a week. Not positive I will be adding it until I do that test. The fridge is a Black and Decker 4.5 cu/ft apartment fridge. I have had it for 2 years now as a spare, it is about 18in shorter than the Dometic it is replacing. Looking forward to the added shelf above the fridge. Ideally a taller fridge would be better and when I get one I probably will do another install, but I have this and the fridge part is larger than the Dometic fridge but the freezer is tiny. Since it can hold my ice cream its large enough for me.Doing the stress test today since I am home on kid patrol all day. Charged battery last night and have been running the fridge for 8 hours nowOpen circuit voltage is 12.52 and running is 12.40Let's see what it looks like after 10 hours......I will stop when the OCV is 12.0vYou should be fine.I run my 10 cu ft home fridge from one pair of 6V GV batts. I have no trouble with that setup while traveling or overnighting..Traveling the tow vehicle charge line helps to offset some of the energy being used by the inverter and the fridge..At night I have had no problem running the fridge, plus some halogen lights for a couple of hrs and even running the furnace all night long and still have plenty of battery left in the morning..Although I must note that the inverter I used is a Tripplite PV1250 which is a MSW with a load sense feature that allows the inverter to shut down the output when no AC load is present.. So when the fridge is not calling for cooling the inverter shuts down saving at least 20-25 Ahrs of battery capacity per day.

Funny thing is, this fridge draws as much as the 10cu/ft ones I looked at. Also, the really small one I have at work has the same specs. Go figure.....Specs on the inverter call for .5a no load draw but when I measure it is .18a???Fridge cooled in less than 2 hours with nothing in it to help, still empty and it is at 0deg freezer and 28 fridge set on 4 out of 6. Ambient temp is about 75deg. Going to open the garage and let the sun hit it for a while and see. Compressor temp is the same as when plugged into the house and no additional noise on the cheap MSW inverter.

Battery Life With a Residential Fridge | Good Sam Community

Gdetrailer
Explorer III
Mar 26, 2015
Adam H wrote:
Funny thing is, this fridge draws as much as the 10cu/ft ones I looked at. Also, the really small one I have at work has the same specs. Go figure.....
Specs on the inverter call for .5a no load draw but when I measure it is .18a???
Fridge cooled in less than 2 hours with nothing in it to help, still empty and it is at 0deg freezer and 28 fridge set on 4 out of 6. Ambient temp is about 75deg. Going to open the garage and let the sun hit it for a while and see.
Compressor temp is the same as when plugged into the house and no additional noise on the cheap MSW inverter.

Correct.

Most fridges use the same size compressor the big difference you will see is the bigger fridges will have larger sized coils and more insulation..

I have a small 1.2 cu ft dorm fridge in my basement, the walls are not as thick as my 10 cu ft fridge. The dorm fridge draws the same amount of current but because it has less insulation it runs longer and more often than the 10 cu ft fridge..

Typically home fridges will reach correct temps within 1 hr or so and start cycling unlike a absorbsion fridge which can take 12 to 24hrs to reach a stable temp.

Home fridges also rebound much faster after being opened so if you are in the fridge often it doesn't take much time for the fridge to get back to the proper temps.

High ambient temps doesn't seem to bother ours, I closed off the old RV fridge top and bottom vents and our fridge is open to the inside of the trailer.. While traveling the inside temps in the trailer have gotten up to 90F but The run time doesn't seem to vary much from 20-22 minutes per hr..
quasi
Explorer
Mar 26, 2015
Disregard my earlier post. The Pinnacle my friends bought has an 18 cu.ft. side by side refrigerator with a pretty massive freezer below.
Jim
Adam_H
Explorer
Mar 26, 2015
Funny thing is, this fridge draws as much as the 10cu/ft ones I looked at. Also, the really small one I have at work has the same specs. Go figure.....
Specs on the inverter call for .5a no load draw but when I measure it is .18a???
Fridge cooled in less than 2 hours with nothing in it to help, still empty and it is at 0deg freezer and 28 fridge set on 4 out of 6. Ambient temp is about 75deg. Going to open the garage and let the sun hit it for a while and see.
Compressor temp is the same as when plugged into the house and no additional noise on the cheap MSW inverter.
Gdetrailer
Explorer III
Mar 26, 2015
Adam H wrote:
I don't think there is an issue with adding a third battery as long as it is in good shape. Batteries are not smart and really don't care about mixing and matching, I will test it again when I'm done after I let it sit untouched for a week. Not positive I will be adding it until I do that test. The fridge is a Black and Decker 4.5 cu/ft apartment fridge. I have had it for 2 years now as a spare, it is about 18in shorter than the Dometic it is replacing. Looking forward to the added shelf above the fridge. Ideally a taller fridge would be better and when I get one I probably will do another install, but I have this and the fridge part is larger than the Dometic fridge but the freezer is tiny. Since it can hold my ice cream its large enough for me.

Doing the stress test today since I am home on kid patrol all day. Charged battery last night and have been running the fridge for 8 hours now

Open circuit voltage is 12.52 and running is 12.40
Let's see what it looks like after 10 hours......

I will stop when the OCV is 12.0v

You should be fine.

I run my 10 cu ft home fridge from one pair of 6V GV batts. I have no trouble with that setup while traveling or overnighting..

Traveling the tow vehicle charge line helps to offset some of the energy being used by the inverter and the fridge..

At night I have had no problem running the fridge, plus some halogen lights for a couple of hrs and even running the furnace all night long and still have plenty of battery left in the morning..

Although I must note that the inverter I used is a Tripplite PV1250 which is a MSW with a load sense feature that allows the inverter to shut down the output when no AC load is present.. So when the fridge is not calling for cooling the inverter shuts down saving at least 20-25 Ahrs of battery capacity per day.
Adam_H
Explorer
Mar 26, 2015
I don't think there is an issue with adding a third battery as long as it is in good shape. Batteries are not smart and really don't care about mixing and matching, I will test it again when I'm done after I let it sit untouched for a week. Not positive I will be adding it until I do that test. The fridge is a Black and Decker 4.5 cu/ft apartment fridge. I have had it for 2 years now as a spare, it is about 18in shorter than the Dometic it is replacing. Looking forward to the added shelf above the fridge. Ideally a taller fridge would be better and when I get one I probably will do another install, but I have this and the fridge part is larger than the Dometic fridge but the freezer is tiny. Since it can hold my ice cream its large enough for me.

Doing the stress test today since I am home on kid patrol all day. Charged battery last night and have been running the fridge for 8 hours now

Open circuit voltage is 12.52 and running is 12.40
Let's see what it looks like after 10 hours......

I will stop when the OCV is 12.0v
vic46
Explorer
Mar 26, 2015
Is there not an issue regarding a third battery to the system that may not be compatible with the two already there? Do they not need to be in sync regarding their individual capabilities? For example, would pairing a new and an old battery not result in the demise of the new battery?
I am also curious as to the size of the "residential" refer you are using.
Vic
quasi
Explorer
Mar 26, 2015
Some friends just bought a Pinnacle with the residential fridge. They get 1 day out of a single 12v deep cycle battery. They weren't using many other loads so I think this is a good number.
Jim

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