Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Topic: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge) (Read 2010 times) previous topic - next topic - Topic derived from Yacht Fridge VS Resid...

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #25 – May 31, 2016, 02:17:10 pm

OH, That explains a lot! 🤓

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #26 – June 01, 2016, 11:18:11 pm

Refrigerator Power Use Science Project

Wednesday Evening, 134 hours into this test.

Measured at the refrigerator...
Average watts per hour, 53.8
Average Amps per hour, 4.3

24 hours on the inverter, started at 10 PM last night, 100% charge, 13.03 volts
After 10 hours, 12.62 volts, 111.7 amp hours used, 88.5% charge, 60 hours left until charge required.
After 19 hours, 12.31 volts, 221.8 amp hours used, 78% charge, 39.3 hours left until charge required.
After 24 hours, 12.17 volts, 278.8 amp hours used, 72.3% charge, 12.6 hours left until charge required.

That is an average of 11.62 amps per hour or 145 watts per hour at 12.5 volts. 91 watts are going to run the inverter and other basic loads.

I am going to go back to the land line and end the experiment.

Conclusions

The refrigerator uses very close to the 51.8 watts per hour average use estimate over a year from Samsung.
The inverter uses more power at idle than the refrigerator.
With no other loads three 8Ds will power the inverter, basic loads and the refrigerator for 24 hrs or more.
A shorter battery duration which most experience is due to all of the other loads we place on the batteries, much more than the refrigerator uses.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #27 – June 02, 2016, 11:57:48 am

Good info, thanks for the effort.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #28 – June 02, 2016, 01:15:27 pm

Roger you are a wizard.

Thanks.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #29 – June 02, 2016, 01:51:37 pm

Good information. These are numbers we have needed.

I have a 12v Amp-Hour meter on order, expected next week. I'll hook it up to my Sea Freeze 12v marine refrigerator and share my results.

I'll post on the original thread this one was split from.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #30 – June 02, 2016, 02:12:03 pm

Tom
What 12v meter did you order?

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #31 – June 02, 2016, 03:10:34 pm

Good job, Roger, establishing a base usage. You have verified that Samsung's power claims are for refrig/freezers that don't ever have the doors opened. I always wondered about that.

How much effect do you think opening the ref/freezer doors 10 or more times per day would have on the usage? Would it double? Triple?

Thanks for the experiment data.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #32 – June 02, 2016, 04:01:12 pm

Quote from: Ed – June 02, 2016, 03:10:34 pm

How much effect do you think opening the ref/freezer doors 10 or more times per day would have on the usage? Would it double? Triple?

I haven't read all the posts in this thread, and we haven't moved to a residential yet. Mostly because we have other projects the fire (putting a house on the lot our shop/apartment is on for our son and his family is the major project right now).

But I am a believer in a separate, lower powered, inverter for the refrigerator only and turning off the main inverter. You can now buy decent 1000 watt inverters with a 0.5 amp idle current. In my, admittedly old and out-of-date, U225 we have several smaller

Solar panels make the perfect companions for residential refrigerators. At one time, not long ago, 200 watts of 12vdc solar was the most common installation and 400-watts was a big install. Now, with 24vdc panels, 500-watts is about the minimum for an RVer who boondocks even a moderate amount. I'm putting 1kw on (two more 250-watt solid panels) before the DW retires.

With solar the open/closed door issue pretty much goes away since during the day the solar panels take up the slack (as long as there is sun) and during the night the doors aren't open very much until morning.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #33 – June 02, 2016, 04:07:18 pm

Samsung says the energy guide is for normal use. What is normal? If I take out the warmstart up I was averaging about 50 watts per hour. 10% maybe? Is the refrigerator door open 2.4 hrs a dsy? May be if you have kids.

A fuller freezer or refrigerator uses less energy.

Everyone's use will be different. The bottom line is that power use is not bad. Pretty manageable. Solar should be able to support a residential refrigerator in sddition to other loads.

Now I want to see what other things use. Especially a 12v refrigerator over time.

And do the same tests with my 1000 watt Magnim inverter. At full load it is supposed to consume just over 1 amp for its own operation.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #34 – June 02, 2016, 04:15:32 pm

Tom
I have a Victron battery monitor from Bay Marine. It accurately measures amp hour and watts withdrawn from the piggy bank. It will do this kind of measurement as well as more.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #35 – June 02, 2016, 04:21:57 pm

Quote from: Roger & Susan in Home2 – June 02, 2016, 04:15:32 pm

I have a Victron battery monitor from Bay Marine. It accurately measures amp hour and watts withdrawn from the piggy bank. It will do this kind of measurement as well as more.

That sounds like what I'm looking for, Roger, does it measure both banks, even if we're off shore power?

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #36 – June 02, 2016, 04:58:11 pm

The 702 does complete monitoring of house and voltage on start.

Victron BMV-702 Battery Monitor

The 700 monitors one bank.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #37 – June 02, 2016, 05:09:31 pm

Quote from: prfleming – June 02, 2016, 02:12:03 pm

Tom
What 12v meter did you order?

FT08 RC 150A Hight Precision Watt Meter Power Analyzer w Backlight LCD US...

FT08 RC 150A Hight Precision Watt Meter +Power Analyzer w/Backlight LCD US Stock

Also available on Amazon.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #38 – June 02, 2016, 05:17:57 pm

If I like the FT08 enough (love the initials, FT), I'll get two more, and put one each on the refrigerator and freezer compressors, plus one on the solar charge wire to the batteries. Knowing individual amps and amp hours might be useful.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #39 – June 02, 2016, 06:01:33 pm

Craig, we have a 1000w inverter (p Sine) and it uses almost nothing to run where as the Xantrex is a hog just to sit there. The small one is on all the time we are travelling except when on shore power which is not often. Solar is total charging for batteries and engine batteries also have dedicated panel on roof. The 1000w one powers fridge, tv, stereo and my VMSpc while driving and now also a new out let next to couch for USB pad and phones. We have absolutely no issues with charging the 3 8Ds and do not run genset. We obviously have a lot of sunny days and can please ourselves where we park at night. Once or twice a week we stay at a RV Park to dump and get water but try to use the Boondocking sites if possible. We do not watch tv but use it for DVD now and again and computer use is just to catch up with family etc. Simple life we lead as we do NOT want to be controlled by the electronic gadgets.
JohnH

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #40 – June 03, 2016, 04:06:36 pm

I love this thread, full of important real world information about how much power a residential fridge will use when boon docking in a Foretravel. However, I would like to comment about a couple of things mentioned that illustrate very common misconceptions about how pertinent dynamic battery voltages are, about how battery recharging works, and about how much power inverters waste.

"Chuck, in reply #3", you indicated that the battery voltage at the start of your experiment was 13.2 and that when the inverter started providing power the battery voltage dropped to 12.7. You also indicated voltages of 12.5 and 12.4 when you opened the refer doors to cause compressor to run. These voltages provide no meaningful information because battery voltage is drastically changed by what is happening to the battery. For example, a battery voltage of 12.4 volts could mean any one of the following three things: ONE, the battery has been sitting disconnected for three hours and is at a state of charge of 70%; TWO, the battery has been providing 6 amps to a light bulb for 20 minutes which has reduced the state of charge from 100% to 99%; THREE, a battery charger is providing 100 amps to a battery at a state of charge of 5%. In conclusion, a battery voltage of 12.4 volts could occur at a state of charge of 99%, or 70%, or 5%; it could also occur when drawing 5amps, 50amps or 150 amps, and even when charging at 100amps. Please do not misunderstand what I am saying, I love what you have done with watts and amps, but the voltages do not provide any additional information.

When boon docking and using solar panels, I read the amphours on the amphour meter to determine the state of charge of my batteries, however, I can use volts and amps to determine what stage the solar controller is in (bulk, absorb, or float) but NOT to determine the state of charge of the batteries. It is actually easier to look at the solar controller display to determine what stage battery charging is in.

"Roger Engdahl in reply #7" you said: "With no inverter loads the inverter draws about 5.7 amps." Are you sure that your inverter draws that many amps at no load. To be sure, disconnect the 120 AC wire at the inverter and measure amps when the fan is not running. My Xantrex pure sign 1800 draws less then 1 amp in ready mode and only 1/4 amp in power save mode (without the fan running). I do not use power save mode because it requires a small AC load like a light to wake up the inverter into ready mode before it will provide power to the toaster or microwave. Instead, because I have an absorption refer, I only turn on the inverter when I am going to use AC power. Note that when this inverter is turned "off" it still consumes 200 milliamps (1/40 amp).

"prfleming, in reply #10" you indicated that to replace 375 amp-hrs consumed, a 125 amp charger would require 3 hours and an 80 amp charger would require 5 hours. Unfortunately, battery charging takes much longer because once bulking is complete (75% charged), a 125 amp battery charger will not charge faster than a 50 amp charger. Such is the nature of a battery. It is not possible to fast charge from 75% to 100% charge without causing the battery to over heat. Charging a battery from 50% to 100% will require perhaps 15 hours.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #41 – June 03, 2016, 04:17:17 pm

Everyone has discussed inverter preferences for residential. .. what about to run the absorption fridge.. use a 400 watt, 500 or 600... bigger?
Pure sine? Why would that matter?

I am contemplating this since my gas won't work... I've got 900 watts solar, a new 240ah battery

OR just use the freedom 25 inverter

Is there an exact replacement for the 24x58x24 in my coach?

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #42 – June 03, 2016, 05:24:39 pm

John. In residential refrigerators you have to look at smaller apt sized refrigs. Lot of folks use them. They are about the size (cu ft) of what you have now but use the space better. The LP refrigerators running on 120v don't cool as well as when they are on LP. They use a heater instead of an open flame. Our seemed to be in OK shape but it really struggled to stay even at 40Â°. Our net cost to switch to a Samsung (do it ourselves) was about $800 after selling the Dometic.

Some motors will do OK with a modified sine wave. Almost anything electronic will do better with a pure sine wave inverter. Figure out what kind of power you are going to need (mfrs stated max power, usually in amps) this is max start up power, and get about 50 % more. They say on my Samsung that max power load is 6 amps, that's 720 watts, I got a great deal on a 1000 watt Magnum inverter. Turns out max loads are closer to 150 watts so I have plenty of room to work with.

These new inverters are much more efficient. They use less power to run and turn more 12 v power into 120 volts. This lets you leave the big inverter off unless you are using the microwave or some other high power user.

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23x22x53 two doors.

Rarely an exact replacement, some trim required.

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Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #43 – June 03, 2016, 05:46:33 pm

Wyatt, thanks for the comments and questions. I have two ways to measure power at the inverter.

One is to put my clamp on meter on the big + 12 volt wire going into the inverter with the inverter on, no land line and nothing using 120 volts on. The meter reads as much as 5.7 amps, some times maybe only in the high 4's. The microwave is plugged in somthat has some idle load. The TV and all of the entertainment stuff is on a switched circuit that is off.

The other way is to check my battery monitor, it tells me how many amp and watts are exiting the battery right now and an amp-hr summary. What that tells me under the same conditions described above is a pretty steady 90 watt draw. Take out the inverters idle load of about 70 watts and that leaves about 20 watts for the radio, the lp gas detector, the co detector, all of the indicator lights, and all of the other stuff I don't know about.

There is no 120v plug on my big inverter/charger. I could turn off all of the circuit breakers. My 1000 watt Magnum pure sine wave inverter uses just over an amp itself at maximum output.

My next step is to try to isolate different sub loads to see what they take.

Added at 7:45 PM CDT
See the spec sheet for the Xantrex Prosine inverter/charger. It says <60 watts at idle with the inverter on. At 12.5 volts that is 4.8 amps. And it is 88% efficient. So to have a 120 watt output the inverter will consume 136 watts from the battery.

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #44 – June 05, 2016, 06:44:51 pm

Roger,
The "No load power draw" of my Xantrex 1800 pure sign with GFCI according to the spec sheet is 20 watts (circa 1.5 amps at 13 volts), while you indicated that your inverter/charger uses 60 watts "no load power". It seems that the addition of the charger adds 40 watts to the "no load power".
I will recheck my "no load power draw" because I quoted it at 1 amp not 1.5 amps - I just need to know.

I use a 50 amp, IOTA converter with set voltage switchable to 13.6v or 14.0v when connected to the battery bank. IOTA indicates set voltages of 13.8v or 14.2v, but those voltages occur only with Open Circuit. I almost never charge my battery bank using the generator (or even shore power).

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #45 – June 05, 2016, 07:31:48 pm

John, here is a link to Beamalarm that I have done years ago and it works sweet. It can run quite a few things as I put in a 1000watt seperate one that looks after res fridge, tv music system and a couple of outlets for charging etc. Works much more efficiently than main one and of course I too have solar about same as you. Like Wyatt I never use land or gen power to charge batteries, just leave it up to solar and alt while driving.
Additional Inverter
Pure sine much safer.

JohnH

Re: Residential fridge energy use (split from Re: Yacht Fridge VS Residential Fridge)

Reply #46 – June 05, 2016, 08:35:34 pm

Wyatt, it is 60 watts with the inverter on. If the inverter is on the charger is off. There is no search mode on my 2001 model.
I am measuring amps into the inverter with it on and no 110 volt loads. The charger is not on. 4.5 amps to 5.5 amps is normal.

Your inverter must be newer and more efficient than mine. That's why I am going to use the Magnum 1000 watt.

I will measure it again.

Roger

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