Residential fridge run time on battery

[Cate&Rob]

I am amazed at how impossible it is to find current draw specs on any residential fridge. Even the calculation of the required EnergyStar label "annual energy use" seems to be a well kept secret. Maybe I haven't found the right combination of Google search words . . . but, I can't find current specs on even one.

Rob

[Second Chance]

I am amazed at how impossible it is to find current draw specs on any residential fridge. Even the calculation of the required EnergyStar label "annual energy use" seems to be a well kept secret. Maybe I haven't found the right combination of Google search words . . . but, I can't find current specs on even one.

Rob

You're right, Rob. I've searched and found any number of technical documents on the Samsung RF18HFENBSR that will come in our Solitude... NONE of them come out and say how many amps/Watts it actually draws. (Only kWh/year or max 10 amp rating, etc.). I did find the following in an article on replacing an RV frig with a residential frig:

"Energy consumption / enegrystar rating (posted on most refrigerators sold in the US); rated in kWh/year. Divide this number by 365 and multiple by 1000 to get the number of average daily watts.
For example, a refrigerator that is rated at 672 kWh will consume 672/365*1000 or 1841 watts per day." [SIC]

The full article is here:

https://rvexodus.com/2019/01/replaci...rigerator.html

(Yet another) Rob

[Cate&Rob]

A big part of this (mysterious) EnergyStar rating has to be the insulation and "air tightness" of the unit. This would directly affect the duty cycle of the compressor. If we assume a 50% duty cycle . . . 1800 watts per 24 hours would work out to 150 watts per hour of run time or 12.5 amps at 12 VDC. This seems (to me) to be quite possible. My 15 year old 10 cu ft residential (boat) fridge draws three times this . . . but this is older technology and probably no longer operating at "designed" efficiency. I do know that this old fridge is well enough insulated to run a 50% duty cycle in 80F temperatures.

In the link referenced above, the author of that article notes that his absorption RV fridge used 8000 watts in a 24 hour period. Many of the absorption fridges use a 300 watt electric heating element. If his fridge has a 300 watt heater, 8000 watts would mean that that his fridge cooling system was operating continuously (100% duty cycle). This goes back to the differences in insulation or air leaks.

There are obviously a lot of "unknowns" in these attempts to compare any fridge to any other fridge.

Rob