Residental fridge, how long on battery

[MetalGator]

I know there are a lot of factors in this (number of batteries, etc) but I am curious what the average run time of a residential fridge will be on a typical class A gas motorhome. The particular model I am looking at has an 1800 watt inverter and 2 12volt batteries. I am assuming the fridge will run off the inverter and the alternator will charge the batteries while driving. We don't boondock but sometimes we stop for an hour or two while driving to stop for something to eat or stop to site see. Just curious if the fridge would run for 2-3 hours without draining the house batteries. My current rig has a electric/propane fridge and if we have a long drive I usually keep the fridge running on propane.

[MetalGator]

The fridge in the unit we are looking at is 11 cubic feet. So it looks like my concerns aren't warranted since it looks like I could run several hours on batteries. Thanks for all the replies. I'm actually going to look at the RV at the dealership tomorrow.

[Searching_Ut]

When we were buying our current rig, most of them had refrigerators in the 18 Cubic Foot range size wise be it residential or Propane/elec. Using the energy star sticker figures and doing the math I came up with energy use of approximately 95 amp hours of 12vdc per day. If you figure 90 percent efficiency for your inverter you'll need approximately 105ah to run the fridge per day. Assuming dual interstate group 24 batteries at 80ah a piece and you can run the fridge for slightly over 18 hours off fully charged batts prior to hitting 50 percent DOD.

Of course you'll have other drains on your batteries as well, and your refrigerator needs will vary with temperature, use etc. so the math as only good as a rough starting point.

[westend]

With two medium sized OEM marine hybrid batteries, you should be able to run the fridge for a day and still be above the happy spot of 50% State of Charge. That assumes fairly modern fridge, typical inverter efficiency, and typical parasitic loads, also. It would definitely be something I'd measure to be sure.

Typical 120V refrigerators use 80-120 watts when operating. The duty cycle is typically 1:4 or 1:3 (depends on ambient and door openings). One fairly accurate way to estimate power consumed is to divide the KWH usage label that is referenced for a year's consumption (yellow Energy Star label on the front of every fridge in the USA) by 365. That will be average daily power consumption.

FWIW, I run a small 120V dorm fridge (80 W'er) off 300AH of battery capacity, through a 1000W inverter. The 12V system is charged by a single 235W solar panel. If the Sun shines, it will run continuously.

I'd bet that if you parked the coach for a few hours and the interior was airconditioned before you parked, the temperature inside the fridge would not rise but a few degrees, even if not powered.

[fairway2002]

I have 8 6volt battery setup. get 17 hours before generator starts.

[Ivylog]

Having wasted way too much money on my NoCold...GO RESIDENTIAL. Assuming a EnergyStar unit, it will run 12 hours on one battery.

[MetalGator]

Thanks for the replies. We are looking at 2 class A's and one has the residential and one has the electric/propane. I initially was hesitant on the residential but it sounds like I won't have an issue with the way we use our RV.

[2oldman]

household refer and inverter2009
Household refer Class A 2009
residential fridge- boondocking 09
Residential refer Class A 2010

[Matt_Colie]

Without even knowing what the two batteries are, yes, you can probably run over night. Without more data, nobody can say.

Matt

[MrWizard]

Yes , no problem
Even before we upgraded the battery bank, we did all night, with only two batteries

[dmck413]

We have had ours on for 24 hours with the furnace at night. Have a 2 battery setup also.