Lowest power consuming 12v fridge

[Spacebar]

Hi does anyone know what the least power hungry fridge is?

I just need a small one for milk marg and cheese preferably a small chest model.

If I end up using a petrol outboard I will only have solar to charge with.

Thanks.

[Castaway]

Thinking a long similar lines, there are a number of 'Cool boxes' that operate on 12V / 240V or just 12V a bit cheaper. Size wise, up to around 30-35L I recall which may be just the ticket for 2l of milk, block of butter and a few tinnies!

 

Thoughts anyone?

[blodger]

Thinking a long similar lines, there are a number of 'Cool boxes' that operate on 12V / 240V or just 12V a bit cheaper. Size wise, up to around 30-35L I recall which may be just the ticket for 2l of milk, block of butter and a few tinnies!

 

Thoughts anyone?

I think that the problem is that peltier cooling is pretty amps intensive, maybe 4 amps continuous. Hence a well insulated, thermostat controlled, compresser fridge wins out averaging 2 amps or less.

[Tam & Di]

Hi does anyone know what the least power hungry fridge is?

I just need a small one for milk marg and cheese preferably a small chest model.

If I end up using a petrol outboard I will only have solar to charge with.

Thanks.

 

 

Models usually have large chests

[Grace and Favour]

Models usually have large chests

 

So did sailors of yore!

[WotEver]

Models usually have large chests

You think?

 

 

Hi does anyone know what the least power hungry fridge is?

Probably Shoreline, but they're not cheap: http://www.boatfridge.com/index.asp?display=thumbs&Col_Category=Fridges+%2D+Small

 

Tony

[alan_fincher]

The small "coolbox" type thingys from Halfords, Towsure, or wherever are, as has been said, massively less efficient in the way they operate than a proper 12 volt compressor fridge.

 

I would suggest they are only sustainable if you are boating every day, and can put back the large number of amp hours they will consume.

 

You really are looking at one of the proper expensive things like a Shoreline, if you want efficient.

 

A great shame, as we have a similar problem with the "new" boat, and it would be nice to buy something that met the "simple" requirement for fifty quid rather than five hundred!

[Tam & Di]

You think?

 

 

 

Well Arnie does, anyway.

 

A long while back we built our own cool boxes for our trip boats that worked very well. Just made a box from blocks of expanded polystyrene or something similar and fibre glassed the inside. Cooling was via a 12v compressor. We only used it to keep beer cool and as we were running the engine all the time it was in use it worked fine. I'd guess that in principal it was more or less like the coolboxes mentioned from Halfords and was very electrically inefficient.

 

Have you (OP) thought of using an Osokool type cooling box. There was a thread about them some while back. They are a porous chalky sort of box which you soak, and make use of the fact that as the water evaporates the box cools down. They work very well, but you do have to be in a position to add more water when they have dried out.

Edited May 27, 2011 by Tam & Di

[Nickhlx]

We have a Waeco 12 volt fridge on board - not sure of make / model / consumption or how "good" it is - the boat builder said it was expensive but worth it, and so far we have had no complaints...

 

I also have an electric coolbox, about £30 from Argos years ago, a Peltier type that takes some 4 amps, the fan whirrs constantly ( too loud to leave on overnight) and whilst it is "OK" in the boot of the car whilst travelling, or maybe on the boat when on a shoreline or travelling, I couldn't recommend it as fridge alternative...

 

Nick

 

 

[Proper Job]

If you're just looking at very small quanities of perishables, why bother with a fridge?

 

A bilge larder (a low down cupboard open to the cool of the bilges) will keep stuff cool for a good while.

 

Obviously, you have to shop a bit more often and you may have to throw the odd but of grub away, but the price of a fridge buys a lot of 1/2 used bottles of milk.

 

?

[Nickhlx]

You could make your own "Osokool" type of box from a plastic container - put 1/2" water in bottom, put your items on a small ledge to keep it out of the water, drape a "tea-towel" over the object(s) and down into the water, wet the tea-towel to start it off and leave in a draught - that will keep the items several degrees lower than ambient, although not so good on humid days as the water doesn't evaporate so fast..

 

Nick

[Roger Gunkel]

There is much to be said for buying a 240v small domestic fridge of the highest efficiency rating you can find. You can run it from a small invertor at a high setting when running the engine or on mains, and turn it off when no power is available. It will also be much cheaper to buy than the alternatives. If it is highly efficient, you will be able to leave it off for many hours without problems. You can also fill any unused fridge space with cool blocks which will help even more. Your solar panel will help to keep the battery topped up and recool the fridge more regularly without needing to drain the battery. Any fridge though would need quite a lot of solar power generation if you wanted to keep it running 24/7.

 

Roger

[Proper Job]

There is much to be said for buying a 240v small domestic fridge of the highest efficiency rating you can find. You can run it from a small invertor at a high setting when running the engine or on mains, and turn it off when no power is available. It will also be much cheaper to buy than the alternatives. If it is highly efficient, you will be able to leave it off for many hours without problems. You can also fill any unused fridge space with cool blocks which will help even more. Your solar panel will help to keep the battery topped up and recool the fridge more regularly without needing to drain the battery. Any fridge though would need quite a lot of solar power generation if you wanted to keep it running 24/7.

 

Roger

Just a couple of thoughts/questions generated by Roger's post.

 

Taking in to account start up current for the compressor, what is the smallest output invertor that would run a 240v fridge?

 

When running the engine, you could do the same with a 12v fridge - put it on high to freeze everything down, then switch off when engine goes off.

 

Definately fill empty space in the fridge with anything (even crumpled up newspaper)

 

My solar panels (2 x 85W) keep up with the fridge in the Summer and some... What would be a reasonable sized panel just for a fridge?

[Randwick]

I used to keep my tinnies cool by wrapping them in a wet bar towel and standing them on the cabin roof - they were always a bit cooler than ambient. Just remember to keep the towels wet, it's the evaporation of the water that does it.

[Spacebar]

I used to keep my tinnies cool by wrapping them in a wet bar towel and standing them on the cabin roof - they were always a bit cooler than ambient. Just remember to keep the towels wet, it's the evaporation of the water that does it.

Thanks for the replies.

In terms of watts how much is 0.85 amps?

Naturally in winter and cold days the fridge would be switched off.

I'm wondering how much more a domestic fridge would consume in power.

I wonder is a cold store in the bildge would work on a fiberglass boat.

Thanks.

[Roger Gunkel]

There seems to be differing opinion on the invertor power needed to kickstart a 240v fridge and experiences seem to vary from make to make. Those running fridges on invertors should be able to give more information.

 

A 240v fridge wouldn't use any more power than a 12volt one and if it is a modern high efficiency one, quite likely less overall even allowing for some invertor loss. A domestic fridge should be considerably cheaper than a 12v one and widely available from any domestic appliance supplier. I don't see why you couldn't use a similar shutdown routine for a 12v fridge providing the insulation level is of a sufficient amount.

 

I seem to remember from my own research when getting my solar panels, that fridges typically use about 40ah per day when left on, but someone with more electrical knowledge could give more reliable information. It would be reasopnable to assume that to power a fridge from solar panels, you would need to be able to average 40ah per day back into your batteries on top of any other power drain. In full midday sunshine at the moment, with my 2x100w solar panels lying flat on the roof, I am getting about 12-13ah charge reading showing from the controller when the batteries are charging from about 80% with no drain.

 

Roger

[alan_fincher]

A 240v fridge wouldn't use any more power than a 12volt one and if it is a modern high efficiency one, quite likely less overall even allowing for some invertor loss.

As I understand it some of the boat fridges sold are basically a domestic type with the 240 volt compressor replaced by a 12 volt one.

 

In those cases, I really can't see how the above can be true.

 

It's usually reckoned that inverters are only about 90% efficient, (pure sine being worse, I believe), so that sounds like a 10% extra hit (at least)using 240 volts to me.

 

The standby current of some inverters is not insubstantial. This of course is irrelevant if you would have it switched on non-stop anyway, but if you are doing this only to run a fridge, then you would have the standby current of the inverter all the time, even if the fridge thermostat only switched on 50% of the time.

 

Given the OP talked about charging only with a petrol outboard, or solar, it doesn't sound like a 240 volt fridge is going to be the best solution for them, to me at least.

[Roger Gunkel]

As I understand it some of the boat fridges sold are basically a domestic type with the 240 volt compressor replaced by a 12 volt one.

 

In those cases, I really can't see how the above can be true.

 

It's usually reckoned that inverters are only about 90% efficient, (pure sine being worse, I believe), so that sounds like a 10% extra hit (at least)using 240 volts to me.

 

The standby current of some inverters is not insubstantial. This of course is irrelevant if you would have it switched on non-stop anyway, but if you are doing this only to run a fridge, then you would have the standby current of the inverter all the time, even if the fridge thermostat only switched on 50% of the time.

 

Given the OP talked about charging only with a petrol outboard, or solar, it doesn't sound like a 240 volt fridge is going to be the best solution for them, to me at least.

 

I wouldn't have any particular basis to disagree with your points Alan, but a quick google for 12v fridges didn't find me any domestic types with 12v compressors. Nearly all the ones I found were the car or cooler types which would not be very economical or efficient. The others were the typical caravan types which seemed to be purpose made and not with efficiency ratings as high as the domestic ones, hence my suggestion that an efficient 240v unit may overall use less power.

 

Any information you have on equally efficient 12v units would I'm sure be of interest to the OP and anybody else interested as I certainly don't claim to have any great knowledge in this area apart from my own experience for my own use.

 

I'm not sure of the relevance of the OP's outboard and solar panels to 12v only, as the battery still needs to be charged whether it is for direct 12v or via an inverter.

 

Roger

Edited May 28, 2011 by Roger Gunkel

[Roger Gunkel]

Just did a longer trawl of the internet for 12 and 240v fridges and found several 12v models from Aquafax and Dometic as the more efficient models, but the power useage seems generally about 20%+ higher than equivalent sized 240v fridges. The prices also seems to start at around £350 upwards, whereas mains domestic units can be picked up from less than £100 for 'A' rated units. This really cheap Tesco offering Fridge as an example, is £91.89 and a consumption of only 141Kwh per annum or about 2.6Kwh per week. So far I can't find anything near that of an equivalent size for consumption in 12v even allowing for a 10% inverter loss.

 

Roger

[blodger]

Not the lowest power consuming fridge but gives you three options:-

 

Item number: 220789829141

 

Ebay second hand 3 way fridge Lcestershire 5.50 and less than 24hrs to go

[Spacebar]

Many many thanks Roger for taking the time.

At present I have a 300w inverter in my van would that be ok with the small fridge you mention?

I would simply turn off the inverter too as my tv will be 12v and everything else.

Mobile and lap top will be plugged into inverter when needed probably when fridge is running.

Seems like I may well need to consider a little genny too incase.

Thanks again.

Edited May 28, 2011 by Spacebar

[paulcatchpole]

Many many thanks Roger for taking the time.

At present I have a 300w inverter in my van would that be ok with the small fridge you mention?

 

The Tesco one?

 

I don't think a 300w inverter would be able to start the compressor motor - I'd expect them to pull a fair bit of stall current on startup.

 

I've a 600w MSW which will only just start my mains fridge, and even then it tends to beep overload when the compressor fires up.

 

The 1500W pure-sine on the new boat doesn't mind at all.

 

PC

[Roger Gunkel]

Many many thanks Roger for taking the time.

At present I have a 300w inverter in my van would that be ok with the small fridge you mention?

I would simply turn off the inverter too as my tv will be 12v and everything else.

Mobile and lap top will be plugged into inverter when needed probably when fridge is running.

Seems like I may well need to consider a little genny too incase.

Thanks again.

 

It was quite interesting comparing different types and hope it has been of some use

 

I am not qualified to give an opinion on what inverter would be suitable and it really needs someone with more electrical knowledge to offer advice. What I would say is that it is not the overall power consumption of a fridge that dictates the size or type of inverter, but the surge of power needed to start the compressor. Your 300w inverter may well have enough output to sustain the fridge, but possibly not start it. I think the smaller fridges are in the 135w consumption range which on paper looks fine against your available 300w, but you may well need 1000w or more to kickstart it. I use a soft start inverter, which doesn't cut out with a sudden heavy load.

 

Don't forget that a higher power inverter doesn't use all the power it is rated at, so a 1000w will only consume what you are using, but can handle more when required. Bigger units though will have a higher background drain though if they have built in cooling fans etc. There have been other threads about this subject and inverters generally, so it might be worth doing a forum search.

 

Roger

[alan_fincher]

I'm not sure of the relevance of the OP's outboard and solar panels to 12v only, as the battery still needs to be charged whether it is for direct 12v or via an inverter.

Only that if this is his total charging capability, trying to support an inverter and a domestic 240 volt fridge might be a bit of a challenge.

 

Are you suggesting that several 12 volt "boat" fridges that use the 12 volt Danfoss compressor are inherently less power efficient than a 240 volt one powered through an inverter. I thought there had been studies that showed them as very efficient, and I doubt the inverter / mains fridge combination is generally going to be more so.

[Roger Gunkel]

Only that if this is his total charging capability, trying to support an inverter and a domestic 240 volt fridge might be a bit of a challenge.

 

Are you suggesting that several 12 volt "boat" fridges that use the 12 volt Danfoss compressor are inherently less power efficient than a 240 volt one powered through an inverter. I thought there had been studies that showed them as very efficient, and I doubt the inverter / mains fridge combination is generally going to be more so.

 

I'm not suggesting anything Alan and have absolutely no idea whether a Danfoss compressor is less or more efficient than any other type. What I am saying is that in response to the OPs post, I have had a trawl through various fridges currently on the market, both 12v and 240v and the technical specs for overall performance tells me what I have posted here. A Danfoss compressor may well be more efficient than other types, but it is the average power consumption of the fridge in use, size for size, that is ultimately what is relevant.

 

I have absolutely no axe to grind at all, and if you can find a 12v, 240v or 1000v fridge that will give the OP less power consumption possibilities, I'm sure they will be delighted and I will be armed with more information to pass on to future enquirers

 

Roger