Energy efficient residential refer amp draw

Say .... that is a GREAT hint about the defroster. I will need to take a look and see if I can do the same with my fridge.

Jose

Texas Two Steppers wrote:
Does anyone have information from a reliable source on the amp draw (@ 12v) of an energy efficient residential refers over a 24 hour period under normal operating conditions? (By normal operating conditions I mean full of food, opening and closing 20-30 times a day with an outdoor temp of 85ish.)

I have a 10cu ft Haier home fridge I put into my TT.. I measured it at 90W running (.75A) with a name plate rating of 1.1A.

As you can see my fridge is drawing slightly less than the name plate rating.

I measured the run time as about 20-25 minutes per hr averaging about 22 minutes per hr. Heat doesn't seem to bother it much from what I have been able to tell. We often overnight while traveling during the summer and the temps at night are often 80F..

Now opening and closing 20-30 times a day and that time will be thrown out the door.. I would expect you will have run times closer to 30-40 minutes per hr when accessing it that often.

Something to consider in your calculations is pretty much all home fridges are "frost free". That means that they will operate a defrost cycle which turns on a heater element in the freezer to melt the frost off the coils.. On my fridge that is about a 250W heating element.

My defrost cycle is ONCE every ten hrs of compressor run time.. For traveling I rigged my defrost timer with a switch to disable the defrost cycle.. I reenable the defrost once I get to my destination with shore power..

Depending on the humidity I can go as long as 6 or 7 days before the fridge starts not work as good as it should without defrosting it.

The yellow sticker is close to actual usage but is usually a bit conservative (allows for users with more access events and higher ambients). When doing the conversions to 12V, take into account the loss of efficiency of the inverter. Not all inverters are the same. Some say the constant denominator should be "10" but the newer inverters are slightly more efficient. Wiring has a role in this and I'd suggest to use the largest possible wire gauges throughout. The possible savings of using smaller wire will be surpassed by usage in short order.

I use a smaller 120V fridge so my numbers won't be applicable to yours. I have a smaller 12V power system too.

ScottG wrote:

smkettner wrote:
Don't they all have an energy sticker?
Post what it says in annual kWh and we can convert to daily 12v power.

Yes they do.
You can go to Home Depot's web site (or others) and get all the energy usage specs for a given fridge.
I went on that site and found that if you pay just a bit more and get an Energy Star rated fridge, it will use far less power.
I think that's well worth considering when your running it of your batteries.

Excellent idea. But when calculating what a fridge uses don't look at the current rating on the back or the cord. That is an indicating of the current pull at start up and is mostly irrelevant when figuring out a power budget.

smkettner wrote:
Don't they all have an energy sticker?
Post what it says in annual kWh and we can convert to daily 12v power.

Yes they do.
You can go to Home Depot's web site (or others) and get all the energy usage specs for a given fridge.
I went on that site and found that if you pay just a bit more and get an Energy Star rated fridge, it will use far less power.
I think that's well worth considering when your running it of your batteries.

Don't they all have an energy sticker?
Post what it says in annual kWh and we can convert to daily 12v power.

Thanks for the information. I was figuring around 80 to 100 @ 12v but my information is several years old.

I agree approx 1.2 kwHrs aka 100 ampHrs

So, simple answer to your question, ours uses just around a kilowatt per day. A little more in the summer, a little less in the winter. So lets say around 85 to 95 amp hours per day on a 12 volt system. Mas o menos. :) Round it out to a 100 and you are probably golden.


Hope that helps.

Texas Two Steppers wrote:
Does anyone have information from a reliable source on the amp draw (@ 12v) of an energy efficient residential refers

You mean when running on an inverter? It would be ~ 10x the amp draw at 120v.

household refer and inverter2009
Household refer Class A 2009
residential fridge- boondocking 09
Residential refer Class A 2010
Norcold w resi, class a 2014