Peltier cooler

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Peltier cooler

Postby KennethW » Mon Apr 25, 2016 12:50 pm

Has anyone made a cooler for a peltier cooler kit?
http://www.ebay.com/itm/New-Thermoelect ... 4d3c99a3ce
A 2 inch thick canvas covered foam box and $12 a Peltier would be a low cost ice-less cooler.
I already know they are not real efficient and they are limited in the temp different from inside a cooler to the outside.
I have a bigger 120 watt solar panel that I would run it from and let the cooler coast at night with cool pads to hold the temp some what. Or run all the time if power use is not to much when running a Cpap at night.
5000 btu ac for a teardrop is way over kill and take a big generator to cover startup.
Would a rack of less efficient less btu peltier be better with no startup surge?
Any thoughts.
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Re: Peltier cooler

Postby Socal Tom » Mon Apr 25, 2016 1:51 pm

Based on calculators I found online, that unit cools 72 watts ( =21BTU) the typical home fridge uses about 488 BTUs/hour. The power draw on those units is a constant 6 amps per hour ( 72 watts). So when your 100 watt solar panel is in full sun and working perfect it will cover the power needed, but over an 18 hour period ( 6 am to 9 pm)it would use 108 amp hours, Deep cycle batteries carry about 100 AH, but if you want the battery to last more than a few trips you want to stay above 50%, so you would need a 2nd battery. and you would need 10 hours of perfect sun everyday to make up for what you used. ( and your food would still be warm ( These things have a really hard time getting less than 30 degrees below ambient). If the average temp during the day is 80, then the inside temp is going to be something like 50, or maybe 45 when you shut it off at night. Assuming you camp when its warm, then the outside temp over night will be above 45, so it will warm up to 50 ish over night ( being conservative), then it will struggle all day to try and stay at 50. Most fridges at home run around 38 to 42F and a drink is cold when its closer to 33. Your food would probably go bad significantly sooner than you hope, and drinks won't be cold. ( and if you put a warm drink in it, all bets are off)

I have a small 6 pack peltier cooler. I use it in my TV. I take drinks from the fridge or cooler, and put them in the peltier , already ice cold, and it keeps them about that temperature. But I never leave it powered when the engine is off.
Tom

Oh, and as for A/C, 5K BTU isn't as overkill as many people assume. TDs have no attic, and an typical attic with no insulation provides about R24 insulation, the shade can contribute even more, and most houses do not allow hot air to blow under them, so there is more area to cool there. A typical TD probably needs around 3500 BTU. Some of the early petcool people said 2500 didn't do it. You would need over 100 of those things to match the 2500BTU, that would pull way more power than the 750 watts my 5K A/C unit draws ( it runs on a 1000 watt Honda).
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Re: Peltier cooler

Postby KennethW » Mon Apr 25, 2016 2:43 pm

Thank's I knew they where bad just not how bad.
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Re: Peltier cooler

Postby MtnDon » Mon Apr 25, 2016 4:55 pm

I would not waste the money and the time. I have had a peltier powered cooler and found it to be less than satisfactory. But then where I am it is common to have 90+ F temperatures outside.
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Re: Peltier cooler

Postby GuitarPhotog » Mon Apr 25, 2016 7:06 pm

Generally peltier coolers don't cool much more than 40-50F below ambient. Which means your cooler isn't food safe on 90-100F days!

There are peltier packages for DIY that will cool as much as 60F below ambient but the price approaches a compressor fridge.

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