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What makes a 12v fridge twice the price?


Puffling

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8 minutes ago, Halsey said:

The simple answer is because its for a boat!?

Don't forget the other markets ripe for gouging as well: caravan, motorhome (RV in the USA), glamping.

I thought going for a tinier cooled box would make it more affordable. Take a look at this for a cool 490 quid...image.png.b90a2014c29a2b6f34c7b975e809b962.png

https://www.jacksonsleisure.com/caravan-motorhome/cool-boxes/compressor-freezer/dometic-waeco-cdf18-portable-12v-24v-compressor-fridge-freezer/

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4 minutes ago, Puffling said:

Don't forget the other markets ripe for gouging as well: caravan, motorhome (RV in the USA), glamping.

I thought going for a tinier cooled box would make it more affordable. Take a look at this for a cool 490 quid...image.png.b90a2014c29a2b6f34c7b975e809b962.png

https://www.jacksonsleisure.com/caravan-motorhome/cool-boxes/compressor-freezer/dometic-waeco-cdf18-portable-12v-24v-compressor-fridge-freezer/

 

 

This is 'helpful' (if not meaningless)

 

 

Power consumption on 12 volts is a tiny 0.38 to 0.64 amps per hour.

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Make sure your chosen inverter can handle the power surge when the fridge motor kicks in. It may well be over 1kW for a fraction of a second, but you won't find the figure quoted in the fridge's spec sheet; an inverter that only just manages the quoted power figure will almost certainly not be able to start it.

 

Getting a decent wine wave inverter also gives you a better choice of other equipment too, such as a better TV.

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As it happens, I shall have an aged Batts (Lec modified) fridge freezer for disposal. It has a 12/24 volt compressor assembly with controller. You collect...

For the unitiated the  compressor is not just a motor it's the complete 'gubbins' and these units have a cotroller as part of the system. Thus not a matter of changing an electric motor.....

 

 

Waeco CU-85 Compressor Fridge

 

This is what a compressor pack looks like. The motor is the lump on the right...

Edited by OldGoat
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2 hours ago, Alan de Enfield said:

I have a 12v fridge and a 220v Freezer powered via an inverter.

 

The fridge uses ~30Ah per day

The freezer uses ~40Ah per day (but generally freezers 'take; a bit more than fridges anyway).

 

That is what we have a Shoreline 12 volt under counter fridge and a small mains worktop freezer. They use a similar amount of energy to yours.

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Blimey, fridges on boats!?  Is that what people are doing now? 

 

And there was me thinking I was at the leading edge of technology when I bought an Osokool off eBay for about £50.  No Gas, no electrickery, no power needed (just half a pint of water).

 

osokool.jpg

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1 hour ago, zenataomm said:

Blimey, fridges on boats!?  Is that what people are doing now? 

 

And there was me thinking I was at the leading edge of technology when I bought an Osokool off eBay for about £50.  No Gas, no electrickery, no power needed (just half a pint of water).

do you use it in your Castle as well as your boat then? :D 

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2 hours ago, zenataomm said:

Blimey, fridges on boats!?  Is that what people are doing now? 

 

And there was me thinking I was at the leading edge of technology when I bought an Osokool off eBay for about £50.  No Gas, no electrickery, no power needed (just half a pint of water).

 

osokool.jpg

 

That takes me back - I had one of those in my Static caravan at the gliding club, must be 45+ years ago.

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4 hours ago, zenataomm said:

Blimey, fridges on boats!?  Is that what people are doing now? 

 

And there was me thinking I was at the leading edge of technology when I bought an Osokool off eBay for about £50.  No Gas, no electrickery, no power needed (just half a pint of water).

 

osokool.jpg

You can make a fridge that works on the same principal for a lot less than £50. Less than £4-17-6 even.

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13 minutes ago, Jen-in-Wellies said:

You can make a fridge that works on the same principal for a lot less than £50. Less than £4-17-6 even.

Sure, you can make one with what Australians call an "Esky" and some cooling blocks. But I doubt if a plastic tub would look as cool as an Osokool.  

In the specs, I just love the claim, "Nothing to go wrong." Hmm, would that be because it actually didn't do anything at all?

Edited by Puffling
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7 minutes ago, Puffling said:

Sure, you can make one with Australians call an "Esky" and some cooling blocks. But I doubt if a plastic tub would look as cool as an Osokool.  

In the specs, I just love the claim, "Nothing to go wrong." Hmm, would that be because it actually didn't do anything at all?

The are limited by ambient temperature (needs to be reasonably high) and relative humidity (needs to be low), so work better in some countries and seasons than others, but they do work.

I've been tempted to have a play making one for the boat. In winter with the stove on, then the temperature and humidity could be suitable.

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3 minutes ago, Jen-in-Wellies said:

The are limited by ambient temperature (needs to be reasonably high) and relative humidity (needs to be low), so work better in some countries and seasons than others, but they do work.

I've been tempted to have a play making one for the boat. In winter with the stove on, then the temperature and humidity could be suitable.

Raise your stove and stick it underneath.

In fact, how big a peltier plate can you buy??

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5 hours ago, zenataomm said:

Blimey, fridges on boats!?  Is that what people are doing now? 

 

And there was me thinking I was at the leading edge of technology when I bought an Osokool off eBay for about £50.  No Gas, no electrickery, no power needed (just half a pint of water).

 

osokool.jpg

My parents had one of them on their boat.

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2 hours ago, Puffling said:

Sure, you can make one with what Australians call an "Esky" and some cooling blocks. But I doubt if a plastic tub would look as cool as an Osokool.  

In the specs, I just love the claim, "Nothing to go wrong." Hmm, would that be because it actually didn't do anything at all?

 

I've cooled a data centre with 2 Mw of evaporative coolers, so they do work. Thry are better at cooling things down to 20-21°C than 4°C though.

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Kind of on topic, but ever since living aboard I have been dreaming about putting the condenser coils of my 12V fridge behind the insulation of my walls and against the cold hull. Especially in winter I feel like this would save a lot of power.

 

Kind of not on topic at all, but I always had a fantasy about a wind powered fridge/heat pump, where the compressor was driven mechanically. It probably isn't a sensible idea, but it seemed like it would be cool.

 

 

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9 hours ago, ivan&alice said:

Kind of on topic, but ever since living aboard I have been dreaming about putting the condenser coils of my 12V fridge behind the insulation of my walls and against the cold hull. Especially in winter I feel like this would save a lot of power.

It would save power in summer too, I'm sure. Comparing an ambient cabin temperature of 23°C (often higher on really sunny days) to the canal temperature of 15°C, there's a lot of savings to be made, even accounting for the thermal resistances between coil-hull-water.

 

But I would take your idea further. Why not switch off the fridge compressor completely in winter and have a cabinet out on the well deck for perishables, cooled by the outside air? In my student days in halls of residence it was common to hang your milk and butter out the window inside a little plastic carrier in winter (given the pilfering from the communal fridge it was usually cheaper, too).

In fact, couldn't a fridge be so designed that it had a cold air intake, open only in winter, through which cold air was circulated with a small computer fan? Now that would be a 12v fridge with low power consumption. ?

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10 hours ago, ivan&alice said:

Kind of on topic, but ever since living aboard I have been dreaming about putting the condenser coils of my 12V fridge behind the insulation of my walls and against the cold hull. Especially in winter I feel like this would save a lot of power.

 

Kind of not on topic at all, but I always had a fantasy about a wind powered fridge/heat pump, where the compressor was driven mechanically. It probably isn't a sensible idea, but it seemed like it would be cool.

 

 

A much simpler half-way house is to cut holes in the floor and fit computer fans in them. Two 12v fans in series run slower and are not noisy and use very little power. For a 12v fridge you may be able to wire them direct into the control system. On my 240v fridge I control them using thermostat module with the temperature sensor bulb strapped to the compressor output pipe so that when the fridge is running they blow cool air from the bilge over the coils. I've had this system for years, but never attempted to quantify its effect.

 

MP.

 

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17 minutes ago, Puffling said:

couldn't a fridge be so designed that it had a cold air intake, open only in winter, through which cold air was circulated with a small computer fan? Now that would be a 12v fridge with low power consumption.

I like this idea a lot because although I have kept things outside before to save on keeping the fridge on, it isn't exactly very convenient to have to leave the nice warm boat into the elements every time you want a cup of tea.

 

Biggest issue I see is having to cut a hole in the fridge and somehow seal it when it isn't winter. I think repositioning the condenser would probably be a good tradeoff between invasiveness and power consumption. Of course it would work with an inverter/240V fridge as well. I am sure someone here has tried it??

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I saw a boat once where the owner had cut out the bottom of the fridge and sat in on the base plate.  He thought this would mean hardly having to run the fridge at all, until it was pointed out that when he needed the fridge the most, the canal temperature would be much warmer than a desirable fridge temperature and all he would be doing is trying to cool the canal.

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23 minutes ago, ivan&alice said:

I like this idea a lot because although I have kept things outside before to save on keeping the fridge on, it isn't Biggest issue I see is having to cut a hole in the fridge and somehow seal it when it isn't winter. I think repositioning the condenser would probably be a good tradeoff between invasiveness and power consumption. Of course it would work with an inverter/240V fridge as well. I am sure someone here has tried it??

 

It would be rather a brutal act for an existing fridge, I agree. Best kept for when one is starting with an installation and has the insulated cabinet as a separate entity, with the cooling plate, motor, radiator and condenser able to be placed elsewhere. But I can't see your plan of placing the coils against the hull as being easily done without needing to de- and re-gas the system anyway. Or is there a crafty trick to it?

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18 minutes ago, ivan&alice said:

I like this idea a lot because although I have kept things outside before to save on keeping the fridge on, it isn't exactly very convenient to have to leave the nice warm boat into the elements every time you want a cup of tea.

 

Biggest issue I see is having to cut a hole in the fridge and somehow seal it when it isn't winter. I think repositioning the condenser would probably be a good tradeoff between invasiveness and power consumption. Of course it would work with an inverter/240V fridge as well. I am sure someone here has tried it??

On many yachts, the working part of the fridge (compressor etc) is remote to the insulated cabinet.

They are oft retro-fitted using an 'old cupboard' which is insulated and the 'gubbins' put in the bilge or another cupboard etc.

 

Just a couple of examples after a quick google :

 

https://www.marinesuperstore.com/refrigeration/cooling-kits/isotherm-ge80-fridge-kit?

 

https://www.marinesuperstore.com/refrigeration/cooling-kits

 

https://penguinfrigo.co.uk/2017/03/special-offer-air-cooled-fridge-kits/

 

Sprayfoam a 'tin box' (or use an old fridge cabinet) and Robert's your Mothers Brother - you have a 12v fridge for almost 50% of the price of a 'store bought' fridge

 

Maybe NB builders could learn from the yachties ?

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