Residential refrigerator electricity use

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Residential refrigerator electricity use

September 28, 2019, 04:38:16 pm

We have a residential refrigerator in our coach which was installed by the previous owner. Normally when we are underway, I just let the inverter take care of its power needs. So far (about 8000 miles) that has worked fine. But I was curious to know how much it drew in amps and how many kWh it used over time. So I bought a meter and installed next to the switch I installed for the refrigerator. See attached pics.

Thus far the current draw seems to vary from about 1500 milliamps down to about 90 milliamps. I have just been recording the current at random intervals and most of the time it is drawing between 1000 and 1500 milliamps. But occasionally it only draws about 90 milliamps. I assume the compressor is turned off when that occurs. I have also been recording the temperature of the freezer and refrigerator which varies from 0 to -3 degrees F (freezer) and 41 to 43 (refrigerator). We have continued to use the refrigerator while I was monitoring the current draw (i.e., opening and closing the door). I recorded data over about 19 hours. Over that period the refrigerator used 1.43 kilowatt-hours.

So given this draw, would it be wise to turn off the refrigerator when the line power is off and the engine or generator are not running... say for an hour or so? This would be a rare situation (e.g., when the coach is being serviced) since when we take a break while on the road, we normally have the generator on.

The monitor also provides something called "power factor" which is 0.566 for my monitoring period. This is not a term I am familiar with but I did find this Youtube video on PF: https://www.youtube.com/watch?v=P5pFe-StdJw. Does the PF for my refrigerator seem appropriate?

Thanks in advance for any input.

George

Re: Residential refrigerator electricity use

Reply #1 – September 28, 2019, 05:17:00 pm

There are many threads on residential refrigerator power consumption. I called the manufacture of mine and was given the running wattage as being between 133 watts to 193 watts. when the compressor first comes on it pulls 1200 watts for milliseconds then drops to 133 watts and slowly builds up to 193 watts when the compressor head pressure is highest, then shuts down to almost nothing until the compressor cycles again.

Re: Residential refrigerator electricity use

Reply #2 – September 28, 2019, 05:48:44 pm

The internet info on Samsung variable speed dual compressor is that it's never truly off. Barely idling?

My new current home Samsung 4 door counter depth door temp gauges always shows zero and 37 degrees. But it's in a very temp stable location?

Re: Residential refrigerator electricity use

Reply #3 – September 28, 2019, 06:10:43 pm

I get similar values if I convert milliamps to watts, assuming 120 volts AC.

1500 milliamps = 180 watts
1000 milliamps = 120 watts
The maximum draw is listed on the label as 6.2 amps which would be 744 watts. I wonder if that is an issue with an inverter supplied AC?

George

Re: Residential refrigerator electricity use

Reply #4 – September 28, 2019, 06:22:42 pm

We find the temps displayed on the door of our Samsung to be inaccurate.... usually diplays -1 and 37 degrees. We monitor the temps with an Acurite thermometer (values cited above).

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Re: Residential refrigerator electricity use

Reply #5 – September 28, 2019, 06:48:27 pm

Quote from: George Hatfield – September 28, 2019, 06:10:43 pm

I get similar values if I convert milliamps to watts, assuming 120 volts AC.

1500 milliamps = 180 watts
1000 milliamps = 120 watts
The maximum draw is listed on the label as 6.2 amps which would be 744 watts. I wonder if that is an issue with an inverter supplied AC?

George

It would only draw 744 watts for milliseconds if it similar to my 1200 watts peak

Re: Residential refrigerator electricity use

Reply #6 – September 28, 2019, 07:35:00 pm

George, a 19 hr sample is not long enough to make any long term conclusions. You need to measure power use, preferably in watts so that voltage variances are included, for weeks or months. Outside temps, temps in the coach, the number of times and how long the doors are open all impact power use. We have measured actual power use of our Samsung over 3 and 4 month periods. Avearge power over those periods, some in winter, some in summer is just over 70 watts per hour. Keep on monitoring but don't worry about any short term stuff. Average and peak power use is really all you need.

Max draw for your Samsung is usually short term when you are doing a warm start. It drops quickly but if younare using a dedicated inverter for the refrigerator it needs to have surge capability to handle that load and simultaneously any other loads on the small inverter.

I wouldn't assume that your AcuRite thermometers are any more accurate than what the refrigerator displays. We have those in our refrigerator and chest freezer and moving the sensors around will get you any reading you want.

Look at the energy guide for your refrigerator. This one is for a Samsung RF18HFENBSR countertop depth French Door. 594KW per hour over a year is 68 watts per hour.

I have not seen a Power Factor spec on any Samsung refrigerator. What you state seems low for a very high efficiency refrigerator.

Re: Residential refrigerator electricity use

Reply #7 – September 28, 2019, 08:25:40 pm

Thanks for the input. We are not using a dedicated inverter. Should we be using one?
George

Re: Residential refrigerator electricity use

Reply #8 – September 28, 2019, 09:09:57 pm

George, you don't need a second small inverter but for us it pretty much means the big inverter/charger is off most of the time saving quite a bit of power. The refrigerator and front end electronics run off the smaller inverter full time. It uses only 6.5 watts to be on. There is never any power interruptions switching from inverter to land line or to generator. Solar charges all we need most of the time. If we are plugged in I have a very smart 40 amp charger that charges the start and house banks for any short fall and shuts itself off if it has nothing to do.

It is a choice. Works for some of us.

Re: Residential refrigerator electricity use

Reply #9 – September 29, 2019, 01:39:12 pm

I have a Bosch residential counter depth refrigerator, not sure about the power specs.
I had to move the coach to the street to have work done in the yard were the coach is usually plugged in.
Its been on the street for 4 days now with the refrigerator running on battery power (no charging) and the Victron 3000 inverter running.
When I checked the batteries today they were at 12.7 volts. drawing off (10) Lifeline L16 AGM batteries.

Re: Residential refrigerator electricity use

Reply #10 – September 29, 2019, 05:40:56 pm

Lon, if you are using about 70 watts per hour average for 24 hrs x 4 days and your voltage is 12.7 volts that is about 530 amp hrs. With about 2000 amp hrs worth of battery you should be at about 74% SOC. Nice to have lots of capacity.

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Residential refrigerator electricity use

September 28, 2019, 04:38:16 pm

Re: Residential refrigerator electricity use

Reply #1 – September 28, 2019, 05:17:00 pm

Re: Residential refrigerator electricity use

Reply #2 – September 28, 2019, 05:48:44 pm

Re: Residential refrigerator electricity use

Reply #3 – September 28, 2019, 06:10:43 pm

Re: Residential refrigerator electricity use

Reply #4 – September 28, 2019, 06:22:42 pm

Re: Residential refrigerator electricity use

Reply #5 – September 28, 2019, 06:48:27 pm

Re: Residential refrigerator electricity use

Reply #6 – September 28, 2019, 07:35:00 pm

Re: Residential refrigerator electricity use

Reply #7 – September 28, 2019, 08:25:40 pm

Re: Residential refrigerator electricity use

Reply #8 – September 28, 2019, 09:09:57 pm

Re: Residential refrigerator electricity use

Reply #9 – September 29, 2019, 01:39:12 pm

Re: Residential refrigerator electricity use

Reply #10 – September 29, 2019, 05:40:56 pm

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