Residential Fridge battery run time

I think the issue is everybody is testing a MT fridge. What good is a MT fridge?
Ever pack a cooler? I often start with a room temperature box, put in a layer of ice on the bottom, put about 40% volume of cold (34*), and maybe 10% frozen, then top with ice. Total ice might be 25% volume of cooler. Never had any problem with food spoiling.
I would bet if you turned a room temp fridge on, set it to 36, and loaded to 50% with 34* food, and left the door closed no food would warm to 40, and the fridge would cycle off in a couple hours.
Now let's say you plug it in, let it run for 3 days, you have a box of cold air. As soon as you open the door to put food in, all that cold air runs out on you feet, is replaced with hot air. Your only gain is the inside walls of fridge are cold.
Like I said before, if you really worry about it, stop by the night before, put a bucket of ice in it too cool the walls

I have found it takes LONGER than 2-3 hours to cool down my compressor refrigerator. Sure, cooling starts immediately but it takes hours to cool down even an empty refrigerator. And that is for a small RV sized unit. Before a trip, I turn my refrigerator at least 12 hours before adding pre-chilled foods.

That is in keeping with the consensus information I found with a Google search. Here is an example:
https://publicananker.com/how-long-does-it-take-a-refrigerator-to-cool/

"Full-size refrigerators typically take 12 hours to cool down to 40degF, which is the FDA-recommended food-safe temperature. The cooling time can vary greatly depending on the refrigerator brand and type and can range from 2 to 24 hours. Mini fridges can be set up in less time, with an average cooling period of 4 hours."

austinjenna wrote:

This is one of the big advantages of a 12v fridge.
- The old absorption style needed to be on pretty much overnight to get cold and if you put a bunch of warm food in one, it might take a day or more to get it all down to temperature...so it was important to turn it on well before you planned to use it.
- 12v compressor fridge will cool down similar to a household fridge, so no need to pre-cool the fridge. As long as most of the food is already cold, just turn it on and load it up. Even if it is warm, it will only take 2-3 hours to get cold.

The problem is I cant wait 2-3 hours for it to start cooling and dont want to put food in a warm fridge

Where do you get the idea it takes 2-3 hrs to start cooling?

This is one of the big advantages of a 12v fridge.
- The old absorption style needed to be on pretty much overnight to get cold and if you put a bunch of warm food in one, it might take a day or more to get it all down to temperature...so it was important to turn it on well before you planned to use it.
- 12v compressor fridge will cool down similar to a household fridge, so no need to pre-cool the fridge. As long as most of the food is already cold, just turn it on and load it up. Even if it is warm, it will only take 2-3 hours to get cold.

The problem is I cant wait 2-3 hours for it to start cooling and dont want to put food in a warm fridge

austinjenna wrote:
Thanks. I am not talking about boondocking or solar panels just simply starting the fridge for it to cool down before I bring it home to load up and head out.

It sounds like it will only run a couple of hours on 1 battery

This is one of the big advantages of a 12v fridge.
- The old absorption style needed to be on pretty much overnight to get cold and if you put a bunch of warm food in one, it might take a day or more to get it all down to temperature...so it was important to turn it on well before you planned to use it.
- 12v compressor fridge will cool down similar to a household fridge, so no need to pre-cool the fridge. As long as most of the food is already cold, just turn it on and load it up. Even if it is warm, it will only take 2-3 hours to get cold.

austinjenna wrote:
Thanks. I am not talking about boondocking or solar panels just simply starting the fridge for it to cool down before I bring it home to load up and head out.

It sounds like it will only run a couple of hours on 1 battery

If you are really worried about it instead of turning on put a bag of ice in a dishpan, leave in fridge overnight.

Thanks. I am not talking about boondocking or solar panels just simply starting the fridge for it to cool down before I bring it home to load up and head out.

It sounds like it will only run a couple of hours on 1 battery

The nice thing about a residential fridge is they only take a couple of hours to cool down.

B.O.

austinjenna wrote:
I know there are variables involved here on the manufacturer of the fridge, battery etc... But for those of you that have one assuming the standard group 27 battery the dealer gives you - how long can you run that fridge on just the battery?

Group 27 = about 100 AH, Marine Deep cycle you should not use more than 25 Ah. that's translates (Once you run it through an inverter) to about 250 watt hours (1/4 KWH) note this is at the 20 hour rate. used at the higher rate of the fridge. 1-2 hours run time likely 1.

time2roll wrote:
I recommend 600+ watts solar if camping off-grid and expecting minimal generator use.
Probably 400+ ah of LFP batteries too.

Be very careful of very specific recommendations with no clue what you have or how you use it.

Do an audit of the electrical devices and how long they will be operating. Then based on that size the solar panels and battery bank.