Thermoelectric Coolers

[Guest]

Has anyone had any experience with thermoelectric coolers or fridges, such as the ones sold by West Marine. I am outfitting a Vivacity 650 and thought about trying one, as I am told they are cheap and reliable, although not very efficient.
I'm installing a 13 hp marinized Kubota diesel with a hefty alternator and 2x95AH batteries, so electrical juice should not be a problem. However, I have never used one of these before, so I am hoping for some comments / opinions - Thanks.

 

[Guest]

These coolers are based on a device called Peltier Effect device, ie they are solid state with no moving parts. In the commercial cheap cooler version they are very innefficient but if you have an electronic bent they can be made much better. In a past boat I built a very well insulated ice box and mounted one of these devices into the wall. When you put 12 volts accross the terminals one side gets hot and the other gets cold. You need to bolt a heat sink to each side of the Peltier effect device, the bigger the better and hey presto you have a cold box.

I now have an expensive compressor driven esky which uses a fraction of the power but I don't have the generating capacity and we use it camping as well. It is also much better in extremely hot climes such as ours where we regularly go away in 35-40C heat and our beer needs to be much colder than yours.

One big advantage of the peltier fridge is it makes no noise although I fitted two small CPU fans to the heatsinks to help it stir up some circulation. The other advantage is if you reverse the voltage it will become a food warmer as well! But they are realy only designed to be operating when the engine is generating ie running.

Most of he electronics surplus places have Peltier effect devices and they are fun to play with. Otherwise buy a small compressor driven esky.

 

[Guest]

I have a Supercool mounted in the lid of an ice box. With good insulation and not too big a box it works well, given enough time. But even with the batteries you describe it is risky to operate without the engine running - very amp hungry, athough the Supercool will detect low voltage and stop (so it says). But it is expensive - for similar money you coud get a compressor - more efficient but with the same power problems I think.

 

[duncan]

mine packed up - but I don't know why! If they are that simple what can go wrong? Fan still runs etc but no cooling effect.......couldn't resist asking as you seem to know a bit about this type of thing.

regards

 

[Guest]

The el-cheapo Peltier effect devices in these can die, especially if the heatsinks are too small. I haven't taken one of these cheap ones apart. If the hot side gets too hot it will zorch the semiconductor.If you know an electronics fiddler give it to them to have a look at. It may be as simple as an overheat protection circuit dead or something.

 

[steve_cronin]

I fitted one made in New Zealand but marketed here by Ampair (http://www.ampair.com/) On their website is a very detailed description.

It had thermostatic control and two power settings each of which was adjustable. We had ours set to using 1.6amps on "Economy" on the reasoning that the standard 1.0amp would not be effective and left the full boost at 5.5amps. The unit failed under guarantee and we sent it back to Ampair. The returned unit was fantastic! It was much better than new - I don't know what they did to it. It cooled down very quickly and would even form ice on the internal heatsink after a day and a half. Mind you a lot of this was due to the thick insulation on Hunter coolboxes and that we fitted an airtight seal on the lid.

The domestic battery was 110Ah and this coped pretty well as we only used boost when the engine was running - a built-in feature of the unit or when we had just put "warm" food inside.

We fitted an electronic thermometer with the screen next to the control panel (why don't all fridges have these - domestic too?) and this would show <5c almost all of the time. This is the recommended temp for fridges. In really hot weather, to save power, give the thing a chance and to just get a civilised G&T we would fill a plastic container - 5ltr spring water bottle with the top cut off - with ice cubes bought in bags from the marina office. As far as I know Andy Taylor and Wild Horizon still have the benefit of that fridge to this day.

A lot of people knock these units but my experiences with the Ampair XC3000, apart from the early failure

Our new Bavaria 42 has a Waeco compressor fridge which we only got working properly following three months of warm beer & cheese when an engineer in Greece finally found the leak & re-plenished the freon.

You have to remember that with ANY marine refridgeration device that frugal power consumption is going to be essential so don't expect wonders with a unit only consuming 60watts when your home fridge is probably using four times that amount of power.

Steve Cronin

 

[Guest]

Thanks to you all who have posted a reply. Acually, based on your response, I am getting a bit hesitant to proceed down this route, so another idea has come up. I can buy a small household fridge (about 50x50x50cm) that is rated at 50W for about £100 and a 12DC-240AC inverter/charger combo for another £150. This would even leave me some juice to spare for other 240V bits I may find use for later, besides being able to charge my batteries from "ground" power. I see similar sized "marine & RV" fridges advertised at several hundred pounds/dollars from the chandlers and mail order houses, but this is way over my budget. I know they will all claim to be "environmentally rugged" or some bs like that, but if anyone has tried a small conventional fridge the way I am thinking of, I sure would like to hear from you -Thanks

 

[Geoffs]

Sorry to put a bit of a damper on your good idea, but...........

The trouble with a domestic type fridge is that they demand large electrical power to start the compressor. Usually between 5 and 10 times running current. So a 50 watt unit may need 500w to start it. Would probably need a 500w inverter to be safe. The higher current is only for a few seconds so shouldn't drain batteries too much, but you would need cables/fuses etc. to stand the max rating. A higher power inverter may run at slightly lower effeciency at 50watt.

I tried to run a domestic fridge off a 300watt Honda generator, and it wouldn't have it. Probably larger than 50watt running though. Good luck.

 

[duncan]

ty

 

[steve_cronin]

Don\'t be tempted down the absorbtion route...

as these otherwise efficient, motorless and totally silent devices use a flame or electric element to drive the refridgerant around ans so are highly sensitive to installastion angle. The multi fuel fridges sold at caravan shops are often of this type and are positively dangerous on a boat (Narowboats on canals are just about OK) which is likely to be heeled over or rock around if a powerboat.

Steve Cronin