best way to keep chest freezer running during power outage

Your chest freezer (or two), or even your fridge /refrigerator freezer may have LOTS of $$ money worth of valuable food inside. The LAST thing you want is for it to spoil during a longer lasting power outage that lasts more than just a few hours!

Here are a few pointers how to best deal with this situation. And a few recommended items to have on hand which will greatly help in the process.

Much of this is common sense. But it’s important.

A freezer or refrigerator will stay colder, longer, if it’s full during a power outage. The fuller it is, the more cold “mass” inside. The more mass, the longer it will stay cold. It’s simply an important concept to understand. If you know your chest freezer is full, it’s definitely going to stay frozen for a lot longer.

In my estimation, most chest freezers that are fairly full will likely stay frozen for… lets say ~ 24-48 hours. (For those who have direct experience with this unfortunate long-term power outage vs. chest freezer or fridge scenario, lets hear your story in the comments below!)

The freezer within a refrigerator probably won’t stay frozen as long compared with a chest freezer. They’re smaller. Probably less insulated too.

The first suggestion, thick, heavy, blankets! Drape blankets over the chest freezer. It’s additional insulation. Just be aware if there are any slotted vents (don’t block them), because we’re going to intermittently power it up with a generator. Read on…

Size of Generator To Run A Chest Freezer or Refrigerator

You do not need to run a generator full time to keep your freezer or fridge cold during a power outage! Save fuel. Here’s what to know and what to do…

There’s no need for a “Super Max Turbocharged Fuel Injected 500-Horsepower Big Block” generator to get the job done! The power consumption of a chest freezer or refrigerator is not huge. Here’s how it works:

Freezers work like refrigerators, by compressing air or fluid into a small space and then letting that air or fluid expand into another space.

Compressing the fluid makes it give off heat, which happens in the back of the freezer. Letting it expand causes it to draw in heat, which happens inside the refrigerated box.

They run in cycles, triggered by a thermostat inside the freezer.power cycles on and off

(the science behind it)

The energy used while it’s cycled “ON” will likely be in the vicinity of ~150 watts. I recommend that you do what I have done, and easily measure it yourself. Here’s an article on how to do it, “How To Measure Power Consumption of Appliances” .

Caveat: When the compressor fist turns on, there is a higher power consumption (inrush surge current, or, “starting watts”). It begins high for a fraction of a second and reduces to “running watts” after a very short time (seconds or less). This may be ~5x (or more) of normal running power. So, for generator loading, this might be 600 to 1,200 watts, depending.

One of my portable generators is a small 1,000 watt, and it WILL run a chest freezer, even with the startup watts.

I would say a 2,000 watt or higher will be just fine.

How Long To Run Generator For Chest Freezer or Refrigerator During Power Outage

First, you don’t need to run it all the time.

There’s not a clear answer. It will depend on how much cold mass (food) is inside, how well it’s designed and insulated, the ambient temperature of the environment, and whether (or how often) you’ve opened it up to have a look inside.

I can tell you what I recommend, and what I do…

Monitor Freezer Temperature With Wireless or Wired Thermometer

Keep a wireless, or wired, thermometer inside your chest freezers so that you can read the temperature without opening it up during a power outage! This is extremely helpful during a longer term power outage. And it’s just good to keep an eye on otherwise!

I have one in each of my two chest freezers. The readout panel is mounted on the wall right above them. I always know what the temperature is inside. They don’t make my model sensor anymore, but the equivalents can be seen here from amzn:

Wireless Freezer / Refrigerator Thermometer

Wired Freezer / Refrigerator Thermometer

Worst, case, as the internal temperature begins to approach 32 degrees F, time to run the generator. But I wouldn’t wait that long.

Most chest freezers are recommended to operate and freeze foods to zero degrees F or below. I generally set mine to about -10F. When it’s that cold, foods will store even longer. However, during a power outage it’s okay if it comes up higher (as long as it stays below 32F).

Remember, Less energy is required to maintain a given (already cold) freezer temperature than it does to bring it down from a warmer temperature.

If it were me, I wouldn’t even wait until it creeps up towards 32 degrees. Rather, I would begin operating my portable generator to provide power to my chest freezers after ~ half a day has gone by. I would run it for about an hour, several times during a 24hr period for starters…

Simply monitor the internal freezer temperature change and just keep up with it. Your times will vary.

Safety Considerations with Generator

When using a portable generator, always operate it outdoors (not in your garage!). Use high quality and proper gauge extension cord to bring power into the home (e.g. through a window).

Continue reading: Best Extension Cord for your Generator

How To Know Your Freezer Thawed While You Were Away

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