SLIDE WARNING:
I wonder how often one would need to run a refrigerator or freezer - Could it just be a few minutes daily or maybe even every other day?
Depends on the ambient temp surrounding the fridge.
Put it in a hot attic and it works harder, cool basement works alot less.
Much of that depends on the outside weather. My son gets a big kick in the movie 'Ice Station Zebra' where the rescue team rushes in to the crew quarters during a vicious polar storm and to the right of the entrance there is a refrigerator!
A freezer here in Florida during hurricane season, inside out of the sun, would probably need to be run an hour twice a day for four days. Then longer and more frequently. A refrigerator here with milk and dairy within would probably need at least two hours twice a day for three days, then more often. In a milder climate one might get by with less running time but not really much less.
What one is cooling can make a difference. The Pfizer CoViD vaccine must be stored, I believe, at -70° constantly. It is stored in dry ice. Any thawing probably means discarding. OTOH, ice cream here in Fla could stand some mild defrost in summer and still be refrozen quite safely.
These are impressions and limited experience in a sub tropical setting. Common sense and detail of circumstance pose solutions. In the four 2004 hurricanes here a great effort was made to truck in huge quantities of bagged ice. The last few seasons no real effort was made. So many variables.
Here’s the deal with freezers in a grid down situation: Make sure you have on hand cheap indoor/outdoor thermometer (the kind that have a long wire with the sensor on the end). At the first sign of a long power outage put the sensor in the freezer and get the door closed quickly. You should keep a deep freezer at about 0°F in normal times but if you can keep it at 20-25°F short term you won’t lose anything. But it would be good to use up your goods soon as possible.
We were thinking about a standby generator but our co-OP has the power so stable anymore that we decided to run extension cords and use our portable generator because a standby is so pricey and we would almost never use it. Knock wood...
A freezer brought to maximum low and not opened often should be fine for 24 hours at least. I’ve not tried yet, but 4-6 hours of gen time should do that.
Fridge slide.
Depends on the fridge, and how hot it is out. a good one 20 minutes twice a day a poor one 30 minutes 4 times a day.
A fridge or freezer normally runs on only 600watts so the smallest generator you can get will run both at the same time, well pumps take bigger...
I get power outs a few times a year and I run the generator 3 times a day for 45 min to an hour and a half to keep the phones up, do a load of laundry ect. I use the central heating to warm the house up and keep it warm with the wood stove. Well tops off the pressure tank in the first ten minutes, then the coffee, after that things just idle along.
Wasteful on gas but comfortable. I like low stress comfort.
Worth a couple extra bucks a day. And Unless you like pulling on a starter rope, get a OHV Honda. Starts first pull every time. Or buy electric start.
Starting a generator in a dark snowstorm is worth not fighting.