Residential Fridge battery run time

duty cycle may be about 1/3.

2.5 X 24 = 60 / 3 = 20

20 x 120 = 2400 watt-hours

Inverter loses may be 12%

2400 / .88 =~ 2728 watt-hours

2728/ 12.6 = 216 amp-hours per 24 hours.

willald wrote:
This is something I'm curious about also, as we plan to do more and more boondocking, and trying to get an idea of how long our frig (Whirlpool 120V residential model) can keep cool without hookups.

Here are the specifics for ours:
Frig says it uses 2.5 amps, full load
RV has 6 GC2 (225 Amp/hour, 6 volt) coach batteries
Xantrex 2000 watt inverter/converter powers the frig when not hooked up to electricity

Based on this, my rough estimate is that we should be able to keep the frig cool for about two days without depleting the batteries too badly. Three at most, but of course it also depends on what other loads are put on the coach batteries. Does this sound accurate?

Also thinking, if I was to run the generator for 2 or 3 hours each day as well, we should be able to last almost indefinite as far as frig is concerned. Thoughts?

My thoughts and calculations show way less than 2 days. The 2.5 amps @ 120 is 25 amps @ 12 volts. You have 6 x 225 AH @ 6 volts which is 675 AH @ 12 volts. Draining battery bank to 50% gives you 338 AH @ 12 volts. 338/25 = 13.5 hours. Your inverter will cost you about 10% so somewhere around 12 hours. So you will need to fire up the generator about every 12 hours. You need to replenish 338 AH. If you have a good sized charger of about 50 amps that will take about 7 hours to reach a partial full charge. So 14 hours of generator time per day. Every few days you should consider running the generator full time for 24 hours to bring the batteries up to a full charge.

Of course this is based on the compressor running full time. Run time is a big variable and could be much less if the ambient temps are cool, no warm items are added and you don't open the door frequently or for long periods. I would not count on dropping below about 60% compressor run time. That would cut your gen time by several hours a day but probably no less than about 10 hours.

This is something I'm curious about also, as we plan to do more and more boondocking, and trying to get an idea of how long our frig (Whirlpool 120V residential model) can keep cool without hookups.

Here are the specifics for ours:
Frig says it uses 2.5 amps, full load
RV has 6 GC2 (225 Amp/hour, 6 volt) coach batteries
Xantrex 2000 watt inverter/converter powers the frig when not hooked up to electricity

Based on this, my rough estimate is that we should be able to keep the frig cool for about two days without depleting the batteries too badly. Three at most, but of course it also depends on what other loads are put on the coach batteries. Does this sound accurate?

Also thinking, if I was to run the generator for 2 or 3 hours each day as well, we should be able to last almost indefinite as far as frig is concerned. Thoughts?

Even with finite "knowns" there are a million factors that come into play on how long a fridge will run to cool down. The easiest and quickest way to get it to temperature after turning it on is add something cold. Aka- food.

When we go our 2016 unit with a Residential Fridge I did a test and ran only the Fridge for 36 hours on the two factory batteries with a Magnum 1000 watt inverter/charger and the voltage was still at 12.6 volts.

My personal experience with a 10 cu.ft. Haier residential in the motorhome at about 70 degrees ambient is that within 2hours at medium setting, the freezer has cooled to somewhere in the high 20's and the main box is in the low to mid 40's. I have remote wireless thermometer sensor's in both the freezer and main box. Once loaded, it runs in the upper 30's.

Also, due to a power outage last year, I discovered that it would run for over 12 hours on my 2 house batteries on a 1500 watt inverter.

austinjenna wrote:

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

What I meant was it to be cold enough to put food in.

We all have compressor refers at home and in no way is it cold enough in 2-3 hrs

If you put cold food into it...yes, it's ready right away. Most of the mass that needs cooling is already cool, so there is no delay.

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

What I meant was it to be cold enough to put food in.

We all have compressor refers at home and in no way is it cold enough in 2-3 hrs

When we leave for a trip, I take all my stuff to the storage area that morning, including food. Turn the fridge on, put cold food in the fridge, hook up and head out. No "pre-cooling" necessary. Never had an issue. The combination of the fridge starting to cool plus adding the cold food brings it to the right temp pretty quickly.

As to your original question, we have 2 batteries and solar and I would expect it can run without hookups for a few hours, maybe a day. But while travelling the cord to the truck supplies power. This is the Achilles heel to a residential fridge, they aren't conducive for boondocking. Ok with us as we don't boondock. If we did, I'd have a different setup.

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

If you put cold food in the fridge, it's a non-issue. Put the food in, turn it on...and you are good to go.

There's no need to pre-cool like is needed for absorption fridges.