Residential Fridge battery run time

JimK-NY wrote:
Re-charging the battery bank would take a great many hours of generator run time. A large residential refrigerator is not practical unless you plan on hook ups at all times.

Unless you add sufficient solar--in which case the costs for generator can be ignored.

On any given residential fridge, the Energy Guide sticker will give you a good idea of how many KWH (and thus how many amp-hours) it uses per day.

For example, this fridge uses 702 KWH per year, which would be around 1.9 KWH per day.

1.9 KWH/day would drain around 158 amp-hours from a 12 volt battery per day:

1900 WH/day / 12 volts = 158 AH/day

Note that the fridge will consume more than this amount on hot days, and less on cold days. It's just the yearly average amount.

The inverter you use to convert 12VDC battery power to 120VAC will also waste some power, so you might actually need closer to 200 AH/day (on average) to power your fridge.

Then you have to consider that lead-acid batteries shouldn't be frequently discharged beyond 50-80 percent, and now you need 240-400 AH of battery capacity.

That's for 1 day of operation between battery recharges. If you can't completely recharge your battery every day, then you'll need more battery capacity to keep the fridge running until full recharge is possible.

Ron did a great job of explaining the issues, except I would disagree on the boondocking recommendation. In Ron's example even 6 batteries would only keep the refrigerator running for a maximum of a day or so depending on other electrical use. Re-charging the battery bank would take a great many hours of generator run time. A large residential refrigerator is not practical unless you plan on hook ups at all times.

Our 2019 VanLeigh Vilano 320 has a Samsung residential fridge and Magnum 1k inverter. They draw approximately 160AHr per 24hr period. If you just have one standard lead-acid battery (85AHr) and only run it down to 50% before recharging (~12.0v, recommended if you want the battery to last very long), you will only get ~40AHr or 6hrs of running the refridgerator.

Of course there are several variables, while driving your truck will supply a few AHr (mine does ~3A) which will add to your time, if you run lights, furnace, etc you will eat up some of that capacity, if your battery is not new or in good condition it won't provide the full charge, etc. Bottom line, you really should have at least 2 standard batteries just for campground to campground with a residential fridge in my opinion, the equivalent of 4 FLAs for overnighting, and at least 6 for much boondocking.

I've added much larger batteries, and a whole-house inverter, to our 5er so that I can run everything and boondock for longer periods of time.