Freezer power consumption

Hey guys,

So I'm weighing up my options for fridges and freezers and I was leaning towards having a separate fridge and freezer for flexibility and in case one dies when away I will have a backup option to avoid everything going to waste. However I am now concerned about the power usage from doing that.

Am I right in assuming that (putting aside the million and one variables) a freezer (say 25-35lt) will consume about 3ah+?

I only ask because those are the sort of numbers I am seeing from both freezers and combi fridge/freezers. However the primus duo 55lt claims to average 0.82ah (with dual freezer and fridge compartments). This seems ridiculously low compared to other dual zones like the waeco cf 50 dz and the engel combi?

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Reply By: Member -Dodger - Tuesday, Apr 17, 2012 at 16:43

Tuesday, Apr 17, 2012 at 16:43
Do a search and put in Cryovac.
Then make a decision.
You will get lots of info.
I used to have a handle on life, but it broke.

Cheers Dodg.

Lifetime Member
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AnswerID: 483370

Reply By: Ross M - Tuesday, Apr 17, 2012 at 16:44

Tuesday, Apr 17, 2012 at 16:44
G'day Simon
I have made my own system and use an Engel 39l as fridge and a Waeco 29l as a freezer. Both are fed with heavy cable to prevent voltage drop and in 30 degree ambient temps they will easily flatten 225ah (in 2 batteries) down to require charging in 1 1/2 .
All depends on how much fresh air they get around them, I supply it with a computer fan, and also keep them covered with extra insulation when not using either fridge.

I use 160 w of solar and this keeps things going but with many variables it does prolong the charge life.
I think the only way to know what your fridges are using is measure the current draw of each so you know what they are drawing and then read a book and sit near them for an hour or two and jot down when each one starts and stops.

Do have them loaded and after they have settled into a pattern of operation in similar circumstance to what you will use them you will then have a record of each fridges typical run pattern.
Then you will be able to work out what solar, generator and or battery capacity needs.

Lots of people quote the usage of fridges and it is hard to know exactly what they are presenting and what it means. Some believe the manufacurers ratings/ some speak in Ah usage and some just say an amp rating. You can't work out anything without having the real information at your disposal.
So do your own tests and then use the info to formulate the power needs from the sources you might use.

My vehicle is white/his is balck, my fridges might use less power each day. Check it out.
Work on facts not hype.
Ross M
AnswerID: 483372

Reply By: P2D2 - Tuesday, Apr 17, 2012 at 19:21

Tuesday, Apr 17, 2012 at 19:21
40L freezer will use around 50Ah. If short term storage and keep at -12C in reasonable ambient temperatures can keep it down to 40Ah.

40L fridge depending on ambient temperature averages 16Ah to 35Ah
AnswerID: 483392

Follow Up By: Simon H1 - Tuesday, Apr 17, 2012 at 19:44

Tuesday, Apr 17, 2012 at 19:44
Thanks for those figures. If I'm storing just pre-frozen meat, what is the highest temp I can run the freezer at? Would -5C be cold enough?
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FollowupID: 758640

Follow Up By: Alloy c/t - Tuesday, Apr 17, 2012 at 20:36

Tuesday, Apr 17, 2012 at 20:36
Simon H1 ,, tis time to get real , the variables are so many , day ambient ,,,, night chill ,,,, how often open and close the lid ,,,, cold or hot stuff put into fridge or the freezer ,,,, what works for one / some ,, may not be /work for you ,,, static ?IE: sitting in the one camp for days on end or moving camp every day ??? How big Amp wise is your system to run the fridge or freezer ?? What system do you plan on using for recharging your power bank ?? Solar , GenSet or just run the big alternator under the bonnet ?? Then you come to another part of your Q , "would -5c be cold enough ?" ... Well old son that also has a variable , that being how loooooong you plan to keep it frozen ,, by rights the longer the term ,time wise , the colder [ to stop bacterial degradation of the frozen item ] the better ,,, just have a look at a packet of frozen [ whatever ] from the supermarket and see what temp its [ supposedly ] stored at ,,,,,,,be , - 18c ,,,,,,,,,,,,,, 90% of stomach / food poisoning / or just a bit "off" after a feed is caused by ??????????? Not fully cooked OR stored NOT cold enough / temp variation allowing bacteria to breed.
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FollowupID: 758652

Follow Up By: P2D2 - Tuesday, Apr 17, 2012 at 21:37

Tuesday, Apr 17, 2012 at 21:37
Simon depends on what type of food you want to store at -5C. There are a few foods, but in the main you are looking at -12C minimum for short term frozen food storage. Heaps of information on freezer storage if you do a search on Google.
If you must use a freezer, a 25L is generally big enough for majority of couples for 3 to 4 weeks if carefully planned and packed.
To make minimum 60Ah a day, you need a good power source. I use around 100Ah a day so know well what it takes to ensure that amount of power daily mobile.
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FollowupID: 758665

Follow Up By: exploreaus - Wednesday, Apr 18, 2012 at 07:41

Wednesday, Apr 18, 2012 at 07:41
I have always set my freezer at -4C and have never had a problem.
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FollowupID: 758678

Follow Up By: P2D2 - Wednesday, Apr 18, 2012 at 08:57

Wednesday, Apr 18, 2012 at 08:57
exploreaus posted:
"I have always set my freezer at -4C and have never had a problem."

You can defy to deny the standards of safe food storage for yourself, but don't advise others of bad unsafe food storage practices.

Food poisoning can make you very sick to death. Safe food storage standards is something that is not up for debate.
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FollowupID: 758683

Reply By: Peter_n_Margaret - Wednesday, Apr 18, 2012 at 05:14

Wednesday, Apr 18, 2012 at 05:14
We have a 25L deep freeze (DIY) with 150mm of urethane insulation plus a 130L fridge only with 85mm of urethane insulation. Both use remote Danfos BD35 compressors.
The freezer uses less power than the fridge.
Power consumption is about how good the insulation is.
Most commercial offerings are lousey.

Cheers,
Peter
OKA196 Motorhome
AnswerID: 483419

Follow Up By: P2D2 - Wednesday, Apr 18, 2012 at 09:00

Wednesday, Apr 18, 2012 at 09:00
"Most commercial offerings are lousey." You are being so kind. Disgusting would be a better term. With rubbish like Vitrifrigio around where they waved the insulation over the top of the cabinet.
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FollowupID: 758684

Follow Up By: Peter_n_Margaret - Wednesday, Apr 18, 2012 at 15:35

Wednesday, Apr 18, 2012 at 15:35
Actually, my fridge is a Victrifrigo with a remote compressor (and 50mm of extra urethane) and it has been a great fridge. :-)

Cheers,
Peter
OKA196 Motorhome.
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FollowupID: 758719

Follow Up By: Peter_n_Margaret - Wednesday, Apr 18, 2012 at 15:36

Wednesday, Apr 18, 2012 at 15:36
Actually, my fridge is a Victrifrigo with a remote compressor (and 50mm of extra urethane) and it has been a great fridge. :-)

Cheers,
Peter
OKA196 Motorhome.
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FollowupID: 758720

Reply By: Member - Boobook - Wednesday, Apr 18, 2012 at 08:44

Wednesday, Apr 18, 2012 at 08:44
Like most power / fridge threads on this forum the terminology is mixed up and you won't get meaningful comparisons from the answers above. Some fridge manufacturers, like Waeco also get it wrong in some of their specs.

Firstly Simon, the consumption figures you are referring to are average AMPS, not Amp hours - ah.

Amp hours are a measure of CHARGE available or used, Ie the amount of capacity of a battery or the amount of average amps used over a specified period of time. Replies to your question have assumed a period of 1 hour, or 24 hours depending on the reply.

So the freezer you quote averages 3amps. That is, it would use 3ah over 1 hour or 72ah over 24 hours. Similarly the fridge averages 0.82Amps. Therefore it will use 0.82 AH in 1 hour or about 20AH in 24 hours.

On the battery side, 100AH would be able to run a fridge that uses an average of 3A for 33.3 hours, or a fridge that averages 0.82 Amps for about 115 hours before it is dead flat. BUT and there is a big BUT. You should not go below 50% capacity if you want to look after your battery so your 100AH battery will only last 16 hours for your freezer or 58 hours for the fridge.

People on here are quoting figures like 40ah or 80 ah etc because they are thinking in how many days will the fridge last between charges. This is a 24 hour figure even though they don't specify it.

Second, the current use is usually 3 - 4 times higher if you have a fridge on freeze. This applies to all fridges ( including the Primus) and is because of the extra energy required to remove the heat and hold it that way. Most portable fridges will run almost continuously when on freeze so they draw more current.

Thirdly, that leads to a pet hate of mine - permanent dual zone fridges. For example the Waeco 80 litre fridge which is half fridge and half freezer. It averages 3.5amps all the time. I'll bet the others are no better. The Waeco is actually a freezer that lets the fridge side get warm. ( and very warm at the other end of the fridge.)

The National Luna has a dual zone but you can set each zone separately. So if you use both zones as fridges then the current is low. But as soon as you use one as a freezer then the current goes up. I *think* some of the Primus ones have a similar set up, that could be why they are quoting 0.82amps - when both zones are used as a fridge. If you can set both zones temperature separately then that would be the one I would consider, though I think they also do one about 75l. I would go for that. You can elect to have 2 fridges ( cool for meat and beer, 8 degrees for dairy, veges etc).

The last point is, as others have suggested forget freezing altogether. There are only 2 reason to have a freezer. a)If you want ice cream, and b) for ice for your Bundy and coke. For food storage cryovacing is much more suited to camping. You don't have to choose dinner and defrost it in the morning, you can see what is in the packs, they are flexible so take up less space, and foods continue to marinade. Food will last 2 weeks for fish and chicken and 4 - 6 weeks for red meat.

I hope that helps and not further confuses you.
AnswerID: 483425

Follow Up By: P2D2 - Wednesday, Apr 18, 2012 at 09:05

Wednesday, Apr 18, 2012 at 09:05
"because they are thinking in how many days will the fridge last between charges."
What gives you the idea or right to think you know what people are thinking. That is ridiculous thinking. I work on getting the battery fully recharged every day or a minimum 92% to 95% of the days.
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FollowupID: 758685

Follow Up By: Member - Boobook - Wednesday, Apr 18, 2012 at 10:25

Wednesday, Apr 18, 2012 at 10:25
P2D2 I WAS referring to general terms. AH per day is an arbitrary figure. Though I notice you are using it in some posts. In fact that you used the term exactly as I described. You were referring to 60 AH in a day and you would then drive after one day.

Dur!
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FollowupID: 758695

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