Cool boxes

LittleSister said:
Does a salt solution actually take any more heat to melt than pure water, or is it just melting at a different temperature?
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No, just a different temperature. Seawater freezes at around -2C (and therefore melts around there too). What you're thinking of is adding salt to pure water ice which forces it to melt faster and therefore take in heat.
 
lustyd said:
What you're thinking of is adding salt to pure water ice which forces it to melt faster and therefore take in heat.
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I wasn't thinking of anything! I was just trying to establish whether there is any advantage to ostell's use of saltwater, rather than freshwater, in his/her freezer bottles, of which I was sceptical.
 
Around here (32degrees south) (35 to 40 degreee max summers)every household has a collection of "Eskys" as the original ones were branded. They are used for picnics etc. The original (60 years ago) esky was made of steel with probably sawdust insulation. Modern ones are very cheap come in a variety of sizes and made of extruded plastic. They all work fairly well.
The trick is to choose a size which works for you. I have one about 1 metre long holds lots of goodies but can be heavy when full. We can get them with wheels. I have others about 500mm long and 450 high holds drink bottles standing witha carry handle. Then there are the samll ones for carrying a lunch in about 30cms long. I also have a soft plastic one can be folded down to small pack to go in the suit case for travelling. We just buy a drink in aplastic bottle and freeze that full of water at the first overnight with a fridge. Wouldn't travel without it. Then lastly the supermarkets sell an insulated bag along with their usual reusable cary bags. At about 1 squid they are good to carry the frozen food home in and will keep stuff cold better ina hot car.
All useful all quite cheap. The last mid sized plastic one we got was left by a visitor who was flyying home and didn't want to carry it.
I think all the solid plasticones have reasonable insulation. One trick if you want ice to survive long period is to fit a small ice box in a big one. You can then have a very cold small compartment with the ice then a cool area around that box.
Most boat owners I know find this frozen water ina cool box either built in or portable in preference to the comnpressor fridges. Perhaps because people here mostly cruise just for a weekend unlike UK people who seem to go way on boat for weeks at a time. good luck olewill
 
davidpbo said:
I use an Aldi Peltier Electric Coolbox made I believe By Waeco about £40 I recall, maybe less. as others have said power hungry, it has the advantage over many that it has a mains plug and 12V plug in the lid so can be run off either without a power adaptor.

The advantage for me of this one was that the bottom is an insulated plastic box as per passive coolbox's all the electrical gubins being in the removable top so can be used with ice or freezer blocks. Run at night on deck some form of ventilated cover needed to keep rain off it cools down nicely. I had to modify the handles to stop them falling off.

Mostly we don't have access to power on the boat so use it passively with freezer blocks or more effectively bags of ice or as other have said frozen bottles of water. We do run it off the car whilst on the way to the boat, not sure whether that helps it stay cooler or not.

I would not say it is the best insulated box around. Maybe look at Coleman or Igloo.

The Waeco Cool Ice refered to in #2 looks pretty good to me for a purely passive one, most of the cheap domestic ones don't have much in the way of insulation IMHO.
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I use a similar one as main fridge kaput!.....now looks like this .... http://www.force4.co.uk/4559/Mobicool-26-Litre-12V-Coolbox.html
a little altered in appearance to mine.
A success if kept switched on, very power hungry (so much so that the 12v plug to cigar socket gets extremely hot) yet very cool inside box, handles fell apart at the hinge and I drilled out and put a s/s bolt through each side to keep together.
Insulation not good and warms up in a few hours on a hot day if switched off.
 
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LittleSister said:
I wasn't thinking of anything! I was just trying to establish whether there is any advantage to ostell's use of saltwater, rather than freshwater, in his/her freezer bottles, of which I was sceptical.
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Sorry for that, can't believe I missed the quote in your post that I was replying to! It's very clear you were just questioning Ostell :)
 
William_H said:
Most boat owners I know find this frozen water ina cool box either built in or portable in preference to the comnpressor fridges. Perhaps because people here mostly cruise just for a weekend unlike UK people who seem to go way on boat for weeks at a time. good luck olewill
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It's also to do with the availability of ice. In America it was very easy and cheap to buy bags of ice because that is what people there do when camping and many of the cool boxes are set up for that with drain taps etc. In the UK the more common method was that people had freezer blocks and paid a small amount to have them re-frozen at the camp site over night, this facility is not usually available at marinas. Bags of ice do seem to be more available in supermarkets now in the UK than when I was camping.
 
Scotty_Tradewind said:
handles fell apart at the hinge and I drilled out and put a s/s bolt through each side to keep together.
Insulation not good and warms up in a few hours on a hot day if switched off.
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Exactly what happened to mine, useless when transferring from tender to boat and I fixed it in the same way. I am not aware of the 12v plug getting unduly hot so maybe check your connections.
 
LittleSister said:
I wasn't thinking of anything! I was just trying to establish whether there is any advantage to ostell's use of saltwater, rather than freshwater, in his/her freezer bottles, of which I was sceptical.
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It works!! I've had the containers in a cool box (admittedly not summer but indoors) and still forming ice on the surface after 6 days.

You have used more energy getting the saturated salt solution to freeze so that is more latent energy within the salty ice that will be available to keep the cool box cool. Or words to that effect, long time since science at school.
 
Regarding my mention of chemicals to produce cold (ok, I know that's not quite right.). PBO did an article on it when it was still a relatively new publication - it was that long ago.

Paul
 
davidpbo said:
It's also to do with the availability of ice. In America it was very easy and cheap to buy bags of ice because that is what people there do when camping
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Too generalistic! In the North Maine Woods 1970's I was car camping and getting pretty desperate for ice to keep the food/beer cool (it was August and in the 80s F). No proper stores for at least 100 miles. We came across a ramshackle place with a sign "ICE FOR SALE". Owner appeared with a broom and axe, cleared the sawdust, and hacked a huge lump of ice off. It was of course traditional lake ice frozen in the winter. The cost was minuscule, but there was no way the block would fit into our small coolbox, so most went to waste. Saved the day though.
 
I used my Peltier cool box recently.We had the family coming and as I was plugged into the mains kept it on for about 3 days.Found at the end that the carrots had frozen! Was quite surprised, Might be worth fitting a thermostat to it.
 
We use a passive coolbox with bottles of frozen water. It lasts a lot longer if you put it out on deck and keep a wet towel over it, especially if it's in the breeze. Just tip seawater over it every now and then to keep the towel good and wet.
 
We have used the Aldi 24v/40v box for the last two years. Fine for a weekend if you freeze a pint of milk and a bottle of water before you go. We have just returned from three weeks in South Brittany where temperatures were a little higher than Wales! We found we could get a frozen bottle of water every other day from supermarkets. This was sufficient with the odd top up from shore power to keep the cool box cold enough for at least 4 chilled beers each day, cool fresh milk each morning for the breakfast cereal and stopped the soft french cheeses from melting!
 
VicMallows said:
Too generalistic! In the North Maine Woods 1970's I was car camping and getting pretty desperate for ice to keep the food/beer cool (it was August and in the 80s F). No proper stores for at least 100 miles. We came across a ramshackle place with a sign "ICE FOR SALE". Owner appeared with a broom and axe, cleared the sawdust, and hacked a huge lump of ice off. It was of course traditional lake ice frozen in the winter. The cost was minuscule, but there was no way the block would fit into our small coolbox, so most went to waste. Saved the day though.
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You found ice didn't you?:-) even then. My experience was more recent.
 
We have a Coleman 36 quart box. It has far better insulation than the cheapo picnic cool boxes.

For a W/E 2 pints of frozen milk (a 4 pint bottle won't stand up in the box) and frozen meat for the Sat night BBQ is enough to keep things cold.
 
I have the Waeco 25lt fridge box.They also do an 18 litre version. Both can be set to freeze blocks which you can then transfer to a cold box. The only cold boxes worth having have proper insulation between the walls, such as igloo. Cheap ones are not worth buying.
 
nedmin said:
I used my Peltier cool box recently.We had the family coming and as I was plugged into the mains kept it on for about 3 days.Found at the end that the carrots had frozen! Was quite surprised, Might be worth fitting a thermostat to it.
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I thought peltier would only cool to so many degrees below ambient??

We have a waeco compressor chest in the med and a supplementary peltier when on mains. I understand that 4 to 6 inches of good insulation is optimum. I plan to have some kind of folding ( for space in storing) box with 2 inches of insulation that my peltier box can drop into. Possibly it can then be run intermittently and still keep cool using less battery?
 
pcatterall said:
I thought peltier would only cool to so many degrees below ambient??

We have a waeco compressor chest in the med and a supplementary peltier when on mains. I understand that 4 to 6 inches of good insulation is optimum. I plan to have some kind of folding ( for space in storing) box with 2 inches of insulation that my peltier box can drop into. Possibly it can then be run intermittently and still keep cool using less battery?
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Not sure that is worth doing as it takes so long for the heat sink to cool.
 
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