Battery Life With a Residential Fridge

[Adam_H]

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 prior
I started after the charger was disconnected for 12 hrs and the battery voltage was 13.16v
Hooked 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 12.91v
After 2 hours I checked and the open circuit voltage was 12.82 and dropped and settled to 12.52 while it was running
After 6 hours the open circuit voltage was 12.62 and running voltage was 12.50

Remember 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 there

I learned 2 things
1 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 ease

Specs:
Fridge 6.0a starting / 1.0 running
Inverter HF 750w continuous / 1500w surge
Battery. 1 worn out golf cart battery
Charger. Cheap brand

[dons2346]

jwduke wrote:

Ontarian wrote:
We have a Pinnacle with a Samsung RF197 which I installed two years ago. Powered full time from a Xantrex 1000 watt pure sine inverter, connected to two Group 24 marine batteries. Fridge will run for 16 hours before voltage drops to 11.5. While driving, charge line from truck keeps battery voltage above 12.5, even while driving all day. Check our blog article for details of the installation.

What do you use to keep the doors from coming open going down the road?

Very simple.

[jwduke]

Ontarian wrote:
We have a Pinnacle with a Samsung RF197 which I installed two years ago. Powered full time from a Xantrex 1000 watt pure sine inverter, connected to two Group 24 marine batteries. Fridge will run for 16 hours before voltage drops to 11.5. While driving, charge line from truck keeps battery voltage above 12.5, even while driving all day. Check our blog article for details of the installation.

What do you use to keep the doors from coming open going down the road?

[Bill_Satellite]

As long as the only thing connected to your batteries is your inverter then you have a pretty good test. However, if you also plan to turn on a light or watch TV or listen to a radio or charge your phone or, or, or, or then you still have some additional power issues to consider.
In any case, however, as you can see, the fridge is not going to drain your so quickly that you can't over night and a charge from the Genset in the AM should get you filled up again. For me, it's some generator running at night for lights and cooking and TV, etc. so the battery is fully charged when I go to bed. A bit more in the morning (need coffee and hot water, anyway) and I am good to go for the day.

[kgragert]

Ontarian wrote:
We have a Pinnacle with a Samsung RF197 which I installed two years ago. Powered full time from a Xantrex 1000 watt pure sine inverter, connected to two Group 24 marine batteries. Fridge will run for 16 hours before voltage drops to 11.5. While driving, charge line from truck keeps battery voltage above 12.5, even while driving all day. Check our blog article for details of the installation.

I followed your link. Thanks for the excellent post. I was thinking of doing the same thing, only on a smaller scale.
Never liked the propane fridge, but anytime someone asked in any of the forums they were told a residential fridge wouldn't work.
I'll now add this to my things todo list.

[Ontarian]

We have a Pinnacle with a Samsung RF197 which I installed two years ago. Powered full time from a Xantrex 1000 watt pure sine inverter, connected to two Group 24 marine batteries. Fridge will run for 16 hours before voltage drops to 11.5. While driving, charge line from truck keeps battery voltage above 12.5, even while driving all day. Check our blog article for details of the installation.

[Adam_H]

Hi all. I disconnected the battery after 12 hours because I was leaving the house for a while. OCV was 12.4v but since I wasn't going to be around for several hours I didn't want to leave it going.

[Matt_Colie]

Adam,

We have run just about that same rig since the OE reefer went flat. The big difference is a pair of older GC2s, we can hold up for about 36hrs in 90° weather. After that, I have to get the APU running to keep things working.

Matt

[Adam_H]

I agree. I have been good with all my power usage and the 2 batteries currently installed in the trailer. By adding the small residential fridge I introduced a variable into the equation. Hence my stress test. If I add the fridge and another battery, that helps me close the gaps on this variable. I have a 12v lcd tv and the normal 12v draws already installed and usually have about 2-3hrs per day of gen time. No solar

Theoretically if I add the battery with the fridge the very few times I dry camp the gen time should only increase by the amount of time my converter take to charge the extra battery. My goal was to be sure I can make it through the night which I am sure can easily be accomplished.

[MrWizard]

our fridge could run on batteries and solar several days,
IF we were not home
But we full time, and its all the other things we do that push the limit
right now we are dry parked under a shade tree, its 90+ outside we have three small desk size fans running and 1 20" box fan, this laptop and fridge

ALL of it running from inverter power from the batteries with some partial solar charging taking place

dinner time will be a two hr generator run, cook with MW, watch the evening news and top up the batteries

its NOT just about the fridge, unless you weekends only and spend all your time outside

if you full time or other extended camping there are Other "power needs" besides the fridge

we love our residential fridge,

but the number of batteries needed varies with the Person and the USE

Adam have fun.. i'm sure it will work out for you

[Adam_H]

10 hours now. OCV is still 12.5v. Running is 12.38v

[Gdetrailer]

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]

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]

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]

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.