Fridge Power Consumption.

Submitted: Sunday, Sep 10, 2017 at 20:58
ThreadID: 135569 Views:15208 Replies:15 FollowUps:9
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I"ve seen several threads here asking about power demands of portable fridges, I have done a test with a 50 lt Waeco and an 11 lt Waeco over a few weeks and here are the results for anyone interested.
I have been waiting for my 50 lt fridge to die so I can replace it with a dual zone but it refuses so I bought a CDF11 to use as a freezer, my 80watt solar panels would run the 50 lt Waeco no worries but I was concerned about running a freezer as well. I now have a 150 watt blanket panel from SCA, very easy to store.
The 50lt Waeco set to +2 dec as a fridge averaged around 0.22 Ah and when set to -10 deg as a freezer averaged around 1.1 Ah.
The CDF11 when set to +2 deg averaged around 0.2 Ah and when set to -10deg as a freezer averaged around 0.85 Ah.
So with my 50 lt fridge at +2 deg and my CDF11 at -10 deg I could expect an average current consumption of around 1.1 Ah.
So overnight , say 16 hrs, when solar panels don't do much both the fridges would consume about 18Ah from my battery, or about 20%.
The following day if my solar panels generate about 5 amps, being conservative, means that this energy would be replaced after about 4 hours of sunlight, in fact with the 150 watt blanket and a Chinese MPPT regulator I see just on 10 amps in good sunlight.
It was interesting that both fridges drew considerably more power for 2 to 3 days before stabilising, so it would be well worth pulling them down on house power before setting off.
These tests were performed without opening the fridges, frequent opening may increase the power consumption, and in an environment of around 20 deg so in 40 deg heat the power consumption would be higher.
When it warms up a bit I will be off again, with my power monitor, and should be able to provide some real world figures, keep you posted.
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Reply By: RMD - Sunday, Sep 10, 2017 at 22:16

Sunday, Sep 10, 2017 at 22:16
I think you have your figures all stuffed up completely. My Engel, heavily insulated, runs for about 30min approx, maybe more each hour, set at around 4 C.
Whilst running it draws at least 2 amps and therefore it is consuming at least 1 AH each hour. Often more.
I have a Waeco 28 and with it set to freeze properly it will run much of the hour each hour. It draws around 3 amps or a little more. Around 4 amphour consumption over 24 hrs is close to a 100 ah per day. Maybe a little less.

I cannot see how a 50 litre fridge used as a fridge will consume such a small amount.
A CF11 is known to be inefficient because of it's size and if used as a freezer, it will be running often and using approx 2 AH of power. It will draw around 3Amps when running.

In HOT weather both fridge and freezer will increase their duty cycle to enable contents to remain as is. The CF11 will possibly be running all the time, maybe stopped for a couple of minutes.
Did you test in very a very cool environment? If you did then the figures don't mean much.
Even if the fridges are cooled down first and contents also cool or frozen where applicable, out in Australia where the temp gets to 30C or more and inside vehicles where it is far hotter, (presumably where you carry your fridge'/s), they will be in a hotter environment than the day temp. In the evening the car doesn't cool down quickly.

I have 160 watt of solar and 40 portable. No way will they keep up with the fridge/s use in central OZ.

Something just doesn't add up to me. Maybe the power meter is not telling you the real story. If you have a Chinese MPPT reg, is it really an MPPT reg? Many of the MPPT branded regs from China have no MPPT in them but the case is branded MPPT. I have two of such devices and they are definitely not MPPT.
AnswerID: 613665

Follow Up By: RMD - Monday, Sep 11, 2017 at 13:25

Monday, Sep 11, 2017 at 13:25
Just a P.S to above.

I use a cooling fan on my fridges to supply fresh air to both condensors. It is a computer fan, it is economical to run and IT uses 0.2amps while running, ie 200MA and so in just 1 hour it uses 0.2 AH of energy.

ANY fridge uses far more than a computer fan. Just have a look at the cable size to a computer fan and a 12 fridge. That should be a basic indicator.
FollowupID: 884187

Reply By: William P - Sunday, Sep 10, 2017 at 22:25

Sunday, Sep 10, 2017 at 22:25
I have a 25l Everkool RV that I use for as a freezer or as a fridge for weekend trips. I also have a ebay 55l fridge that I use as a general purpose fridge. I have watt meters on both.

Like you, I have found that for their size the smaller fridges use far more power than the bigger fridges and in absolute terms actually use more power when ambient temps are higher. I guess this is because of their thinner insulation.

I think your plan to go with a dual zone is the way to go as I believe they would use less power than the two fridges. Like you I am waiting for the ebay fridge to die to get a dual zone but it just keeps running and running well and as far as I can tell doesn't use any more power than the popular brand names. I will keep the small RV fridge for short weekend trips where freezers or big fridges are not needed.

Thanks for posting your results.

AnswerID: 613666

Reply By: Les - PK Ranger - Monday, Sep 11, 2017 at 00:14

Monday, Sep 11, 2017 at 00:14
Regarding the SCA folding blanket solar panel.
I have this as well as the smaller 100w I purchased a few years prior, both still going strong.

They are great value and awesome performers, particularity the output vs specs.
My 100w specs max 5.71 amps, gets 6a in full sun, 2a in fairly full dark overcast skies (enough to still power Tecnii fridge and put a smidge into battery).
The 150w is + 50% more for all relative above data.

I would do one thing though before using.
Get a few good cable ties and attach the output cable from the case, secure well up one side to where it comes out of the storage pocket.

I had a blowaway once at Mt Finke campsite, but luckily a mate had it all fixed by the time I returned from summit walk :)
Wind came up suddenly and even though I had edge under wipers it pulled right out tearing the wires..

That's another thing, always anchor down, even in calm, I use some short mini occy straps, come about 10 or 12 in a small plastic bag, easy to secure.
AnswerID: 613668

Reply By: Iza B - Monday, Sep 11, 2017 at 06:39

Monday, Sep 11, 2017 at 06:39
Thanks for making the effort to provide some info that would be useful to the members here.

I have no idea what 0.22AH means in describing a fridge power requirement. Fridges draw X current when running and run time is describable as duty cycle. Duty cycle is a function of fridge efficiency and ambient temperature profile across a time frame. 18 AH over 16 hours at 0.22AH average just does not make sense.


AnswerID: 613670

Reply By: Sigmund - Monday, Sep 11, 2017 at 07:04

Monday, Sep 11, 2017 at 07:04
Good to have some data.

Yes, opening and adding stuff bumps the consumption up significantly.

And every degree warmer adds 5% to the draw acc to Collyn Rivers.

On that score, on one measurement with 18 degrees outside and the camper trailer parked in the sun with the hatches closed, it was 38 degrees inside the fridge box. So more than double the draw.

My fridge maker quotes 1.5 Ah for my 60 l unit at 4 C fridge mode in 30 ambient. I never see this. 4-5 Ah is common up north.
AnswerID: 613672

Reply By: Member - Boobook - Monday, Sep 11, 2017 at 07:27

Monday, Sep 11, 2017 at 07:27
Ah is not a unit of current, it is a unit of charge. It is meaningless in this context to use Ah figures unless you also quote the time.

Eg a fridge drawing 1 Amp uses 1Ah per hour or 24Ah per 24 hours.
A fridge using 2 Amps uses 2 Amps per hour or 48 Ah over 24 hours.
Also most fridges will average about 1 Amp when used as a fridge and 3A when used as a freezer. That's 24 and 72AH respectively for one day.

So if you have a Battery marked as 100 AH, ie 50AH of usable capacity, that fridge will last 2 days as a fridge and about 16 hours as a freezer before you have a flat battery.

As to the figures you quote of 0.2 and 0.85 AH freezing for the CDF 11, and 0.22, 1.1AH freezing for the 50l. If the units you mean are AH then the figures don't mean anything. If you mean Amps then they readings are incorrect. No fridge will use 0.22A on average and 1.1 as a freezer. Physics won't allow it.

I think you need to do more homework.
AnswerID: 613673

Follow Up By: Member - Boobook - Monday, Sep 11, 2017 at 07:38

Monday, Sep 11, 2017 at 07:38
Answering the question another way.

If you have 2 Fridges, the small one freezing and the big one as a fridge, and if you have 200 AH of battery, it will last a bit less 1 day without recharging. If you have one 100AH battery then obviously you will get about 12 hours of use.

You will need a minimum of 400 - 500W of solar with a MPPT charger to run indefinitely if you have at least 200AH of battery. you can't do it with 100AH of battery capacity.

Keep in mind that if it's cloudy, overcast or raining, or you have ANY shading then 400W of Solar will only output 150, 100, or even 50W. A solar panel's rating it basically its best case output.
FollowupID: 884181

Reply By: William P - Monday, Sep 11, 2017 at 10:18

Monday, Sep 11, 2017 at 10:18
I think that as usual a few people are over thinking this - this is simply the results found by one person and gives the assumptions used - it is not a scientific test.

Accept it for what it is - if it helps you that is great, if it doesn't then move on.
AnswerID: 613674

Follow Up By: Member - David M (SA) - Monday, Sep 11, 2017 at 11:22

Monday, Sep 11, 2017 at 11:22
Depending on the temperature of the cans I find it best to air up ( or down) to allow for the direction of the wind.
Dave. (Moving On)
FollowupID: 884186

Reply By: swampy - Monday, Sep 11, 2017 at 10:32

Monday, Sep 11, 2017 at 10:32
There are many tests online
Consumption needs to be done over 24hrs with notes on ambient temperature ,sun,shade open closed a lot or little
Most fridges will start with 25ah in 24 hrs and go up from there according to ambient temp .
Solar required
160watt produces around 38ah in 24hr
200watt produces around 48ah in 24hr
based on
av. Peak sun hours 5.5hrs summer 6.5 winter 4.5
system power loss 20%
cable loss , controller loss , panel positioning to sun
Mppt and solar outside PSH is a bonus as its unreliable / inconsistant watt production

JohnnyC u did not mention ambient temp [your amp figures suggest it was low
Ah per 24 hr is the only figure that's needed and the MOST accurate
AnswerID: 613675

Reply By: Alloy c/t - Monday, Sep 11, 2017 at 10:33

Monday, Sep 11, 2017 at 10:33
After years and years of monitoring power consumption of my two portable fridge freezers [ from the tropics to the snow to the heat of central Qld and WA ect etc ] your so called figures do not make any sense at all ... a Waco 80lt fridge /freezer set at -15c in the freezer compartment so the fridge area is at 3c will use 64amp/hrs of power each and every 24hrs ,the only variables are ambient temp / opening /closing and the initial temp of items put into freezer section/ fridge section , my now 20 yer old 15lt Engle uses 45 amp/hrs of power per 24hrs set as a ' drinks only fridge' 2c ...summer /winter /insulated cover on/off make very very little difference......
AnswerID: 613676

Follow Up By: Member - Bigfish - Monday, Sep 11, 2017 at 17:58

Monday, Sep 11, 2017 at 17:58
I,ve just returned from 2 week trip to Cape York My 47 litre Evakool , with 40mm internal fan , was used solely as a freezer. Kept inside camper when traveling and under annex when camped. It averaged about 55 amps a 24 hour period. (-15degrees ) . 40 litre engel used as a fridge averaged about 20 amps a day.(4 degrees) Engel kept at all times in back of the Pajero. It also has a cover.
FollowupID: 884191

Reply By: Peter_n_Margaret - Monday, Sep 11, 2017 at 12:04

Monday, Sep 11, 2017 at 12:04
Particularly when comparing fridges, it is critical to understand the difference between power and energy.

OKA196 motorhome.
AnswerID: 613678

Reply By: Les - PK Ranger - Monday, Sep 11, 2017 at 18:14

Monday, Sep 11, 2017 at 18:14
Johnny, do you have your 2nd battery hooked up to charge via the vehicle alternator when driving ?
Sorry if this is somewhere, didn't see it mentioned.

If so, then you may not even need solar unless you are camping for a few days.
I have run a 100amp/hr agm for 5 years now in an arkpak, set up to charge from the vehicle when driving.
If I tour daily, it has no trouble running my techii fridge and leds lights from mid arvo through overnight, aux batt drops to about 83% SOC next morn, then we pack up, move out, and battery is all charged again in very short time, probably no more than a couple of hours.
I have a little Waeco 11lt too, always planned to get it and use as a small freezer on longer trips, but just haven't bothered yet.

As mentioned above, I can take my SCA Ridge Ryder 100w or 150w folding blanket if I plan to camp 2 - 3 days, but in reality have also not had the need (I like driving daily to new camp, touring).
I have used the panel (mostly the 100w) quite a bit on trips just topping off the main or pumping a bit into the 2nd battery if I felt like testing things out after arriving at a daily camp early, say by 1430 / 1500 hrs and a few hours of decent light left.
AnswerID: 613690

Reply By: Sigmund - Monday, Sep 11, 2017 at 20:45

Monday, Sep 11, 2017 at 20:45
There's also some fridge test data here: Click
AnswerID: 613697

Follow Up By: swampy - Tuesday, Sep 12, 2017 at 06:42

Tuesday, Sep 12, 2017 at 06:42
Sigmund ,check your link!!
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Follow Up By: Sigmund - Tuesday, Sep 12, 2017 at 07:41

Tuesday, Sep 12, 2017 at 07:41
Thanks swampy. Here's the correct link:How much power 12 v appliances draw
FollowupID: 884221

Reply By: The Bantam - Monday, Sep 11, 2017 at 20:55

Monday, Sep 11, 2017 at 20:55
A couple of matters.
1/ chilling down contents and chilling down the fridge prior to leaving home IS a major factor ...... I expect to chill the fridge down for at least 24hours.

2/ set fridge/freezer temperatures have a dramatic influence on power consumption.
Remember most household freezers run at -18C and -10C is the absolute maximum temperature for reliable freezer storage

yeh ya might want to run between 0 and 4C for general fridge work ..... but for beer and other cold drinks you need to be at -2C

think about fridge and freezer temps ..... it is a strategic choice depending on how ling you expect things to store and other factors.

3/ ambient temperature has a profound influence on consumption .... heel even on ice and a modes esky I can get 3 days out of a pre-chilled pack in winter, but in summer I'll be lucky to get a full 24 hours before topping up the ice.
so in a fridge freezer it may double or tripple the power consumption.

4/ fridge discipline .... is also another factor.

so just running a fridge with the lid closed in relatively cool weather may result in figures many time lower than reality.

Then we talk about solar ...... that too has many variable factors

AnswerID: 613698

Follow Up By: Les - PK Ranger - Monday, Sep 11, 2017 at 21:42

Monday, Sep 11, 2017 at 21:42
Always good to pack stuff cold for sure.
If taking frozen gear in the fridge for example dinners after end day 3 or so, freeze it for a good week to get deep frozen solid, pack around sides of fridge, other fridge stuff in the middle.

I find when replenishing the days 4 or so cans of beer, I do this in the morning, so when driving for the day there's no extra consumption that matters to the battery under vehicle charge.
If camping, then cans etc can be put into a bowl of water to chill overnight, or keep a creek in a net bag etc to chill, it helps.

Great if you can keep the fridge in the cabin, and block direct sunlight with some alfoil covered cardboard inside the window.

Good to pack the fridge to match the food plan for a trip, no extra time delving to find this and that.
Absolutely very important before opening fridge to think, is there something else I need to get out now, in 15 mins, etc, get dinner stuff out to de-chill when getting that coldie.

It all comes with trips and learning as you go, but nice to get pointers from others too.
FollowupID: 884206

Follow Up By: Sigmund - Tuesday, Sep 12, 2017 at 07:50

Tuesday, Sep 12, 2017 at 07:50
Just eyeball assessments FWIW but I found that adding a computer fan to my 60l fridge in fridge mode plus packing it relatively full dropped the consumption. The fridge has cooling panels around only about 1/3 of the inside - the so-called freezer part - and relying on drift alone meant the far end ran too high, requiring screwing down on the temp setting.
FollowupID: 884222

Reply By: JohnnyC - Monday, Sep 11, 2017 at 20:59

Monday, Sep 11, 2017 at 20:59
I think most people haven’t taken the time to read my initial post, judging by some of the responses.
Just to clarify things a bit, I have spent over 50 years in the electronics industry, and a considerable part of that performing capacity tests on aircraft batteries, and Electrical Load Analyses to determine duration on battery power alone in an emergency, so I do understand the basics.
From this I have access to calibrated measuring equipment and took the opportunity to perform some tests which may be of interest to some people, I did state that they were under ideal conditions and represented the absolute minimum power consumption of the fridges, obviously higher ambient temps, or frequent opening will increase the consumption considerably.
I agree that these consumption figures seem unreasonably low, but under ideal conditions, not for 24 hours as someone mentioned but for several weeks, also remember that it took about 2 to 3 days before the average consumption stabilised at these levels.
Regarding Amps and Amp/hrs, if my fridge consumes 2 Ah of energy over a 10 hour period then the average consumption is 0.2 Ah, it might draw 3 amps for a time then none for the rest but the average is 2/10 =0.2Ah.
Regarding the comment on MPPT regulators, true there are many fakes but I did my research and sourced a Chinese made unit which really works, it converts 5 amps from my panels at about 19 Volts to 6 amps into my battery at about 14 Volts, so there are some real ones, and it only cost me about $120.
That's my two pence worth, I won't comment further.
AnswerID: 613699

Follow Up By: RMD - Tuesday, Sep 12, 2017 at 16:38

Tuesday, Sep 12, 2017 at 16:38
Who on earth runs their fridge for several weeks after stabilization and never opens the fridge. Sort of defeats the purpose.
Unrealistic to state stuff which no one other than a test centre is going to do.
Others here have stated what happens to them with normal use, that is what people buying and using these fridges require to see. I can see the top of Everest too but never going to achieve the climb.

If I drive my 3litre diesel at around 60kmh everywhere I go, I get really good/economical fuel consumption. When used normally much less but I don't take a month to get there.
FollowupID: 884231

Reply By: swampy - Tuesday, Sep 12, 2017 at 06:55

Tuesday, Sep 12, 2017 at 06:55

40-50ah in 24hr period [removing highest and lowest readings ]
ambient average 37 cycling 25-65--25 deg
AnswerID: 613708

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