Refridgeration problem solved!greenspun.com : LUSENET : TimeBomb 2000 (Y2000) : One Thread
Refridgeration has been a major concern for me every since I've been preparing for Y2K. Propane refridgerators are back ordered and to expensive anyway. Like many of the hardcore prepers, I am going to use a generator and solar panels to recharge deep cycle batteries and use inverters and DC appliances powered by the batteries. I ran across a dream come true in Wal-Mart tonight. Thermoelectric coolers! Their a 40 qt. DC electric cooler. They cool the air 40 degrees cooler than the external air temperature.I purchased one of these little babies tonight and hooked it onto a Trojan battery. The house temp was around 80 degrees, and within 3 hours the cooler was at 39 degrees. By my calculations, I believe that the battery will need charged every 3 or 4 days. These things just seem custom made for our situation. I hope this idea helps out some of you fellow Y2Kers.
-- Bugs Bunny (email@example.com), March 13, 1999
Dear Bugs, I hate to burst your bubble, but those 12VDC coolers draw a little more current that you think. I have been using one for a few years in my 18-wheeler and if I leave it plugged in more than about 36-48 hours without running my engine, my batteries are so low the truck won't start. Now this is with a bank of six fairly new heavy-duty 12volt batteries. And while the space in the cooler is about like a large ice chest, it comes up way short when compared to a regular refrigerator.
-- Gerald R. Cox (firstname.lastname@example.org), March 13, 1999.
My plans don't include a refrigerator, but I have stocked up on other 12v goodies to run off of my solar system. A virtual treasure trove of items can be found at RV supply stores. I have noticed they have several different models and sizes of 12v refrigerators. Not being personally interested, I haven't investigated them, but they may have models that are more efficient then those WalMart coolers...
-- Online2Much (email@example.com), March 13, 1999.
An RV propane fridge in the basement may be a good alternative.The cooler the location of the fridge, the less energy it will require.
-- Watchful (firstname.lastname@example.org), March 13, 1999.
We checked prices on propane frig..very expensive..are RV ones any cheaper????
-- Moore Dinty moore (email@example.com), March 13, 1999.
Gerald, I don't know what type of cooler you had, but it must've either been huge or very inefficient to have taken that much juice out of your six-battery bank! I have one of those coolers that Bugs describes, and it has a continuous 4-amp draw. Over your 36-48 hour period, it would use from 144 to 192 amp-hours. Assuming your batteries were each rated 100 amp/hours (small for a big truck), you had a 600 amp/hour reserve. At most, you'd have discharged your bank about 1/3, leaving plenty to start the truck.
However... Bugs, I think you'll find that your single battery will not be able to run that cooler as long as you think. Even if you have a pair of trojan L-16's (300+ A/h), you'll only be able to run the cooler for a day and a half before recharging (battery would be drawn down 50%). If that battery is a small deep-cycle, 24f series case, you'll only be able to run it half a day before needing to recharge.
Bottom line: these coolers are fine if you want to cool a few drinks down on a hot summer day, or even if you want to make a small quantity of ice (I've done it - put the cooler in a 55-degree F ambient temperature root cellar, add ice cube tray, come back in 4 hours - ice!)... but for general refrigeration, not a chance - unless you have the mother of all solar energy systems, or a tanker filled with gas to feed the generator.
-- sparks (firstname.lastname@example.org), March 13, 1999.
The batteries used in trucks (and cars) cannot withstand long, continuous draws -- they aren't made for it. They are designed for large, very short term loads with immediate recharging (once the car/truck starts). Even with 2, L-16 fork-lift batteries (giving 375 Ah at 12 volts), you wouldn't want to power a 4A load for 48 hours.
-- Dean -- from (almost) Duh Moines (email@example.com), March 13, 1999.
Dear Bugs, The problem of refrigeration has also been bothering us.However I came across a possible solution in a forum concerning brewing beer in hot climates.I don't know whether it will work for you.Get a rigid water proof container such as a galvanised bucket or plastic drum.Wrap a damp towel around it and stand the whole thing in a tray of water with the bottom of the towel in the water.As the towel dries out two things happen.1.The energy needed to evaporate the water is taken mainly from the bucket or drum..thus cooling it & its contents.2.More water is absorbed into the towel from the water reservoir in the tray at the bottom so the evaporation/cooling process is continuous. I have seen camper fridges working on this principal.However I don't think the drop in temperature is anywhere near enough to freeze a carrot! Another oldtimers's solution was to build a small shed over a stream and suspend food in the water...thus keeping it cool.
Hope this helps a bit .
-- Chris (firstname.lastname@example.org), March 13, 1999.
We worry about refrigeration too. Being in Australia we're as worried about the heat as you guys are about the cold. I agree gas fridges are expensive, the cheapest one we've been able to find retail is $649 Aussie dollars, (about US411) for a 3 way (AC/DC/Gas unit) it's small, Aussie made and uses only 250 grams of gas per day, we're hoping to find a cheaper option second hand, but we'll go with retail if we can't.
Chris's suggestion re the beer making towel and water method sounds to me like a modification of an old australian invention called the 'Coolgardie Safe'. He's right though, it just drops the temp a few degrees, not exactly refrigeration as most of us would think of it. A quick web search revealed only one ref, from some school's project but its here... http://www.netc.net.au/wangps/hpage3a.htm , for what its worth. I'll see if I can ferret out some better plans, maybe we can apply a bit of modern tech to it and up the efficiency a bit. (Well, I did, and its about as simple as the plans suggest, the classic book on Australian Bushcraft, the "10 Bushcraft Books" by Richard Graves suggests that it can achieve temperatures abot 20 to 40 degrees F less than the ambient shade temperature.)
The big Aussie news for me is Y2k on our Sixty minutes tonight, major prime time current affairs program, a clone of the US version, it often takes US stories but tonight's appears to be genuine Aust. story. I'll tape it and post a decription.
I don't expect much though, its not usually big on investigative journalism!
But, the Australian Government is taking real steps on solving Y2K, we now have series of TV ad's, but they are about domestic appliances etc. An example (paraphrased)...
(Nerdish kid is given present of computer game by DGI parents.)
Nerdish Kid: "Is it OK?"
Parents : (stunned looks, etc)
Nerdish Kid : "Is it Y2K OK, will it work ok after the year 2000?"
Parents : (Look of awakening on faces and apparent amazement at brlliance of child)
Well, gotta go, the sun's shining brightly and I want to have another go at breadmaking in our solar oven (I love those things!), my last one was bit doughy, I think it needed to rise more. It had a great brown crust though, I didn't really expect it to go that brown. Cooking time 2.25 hours if anyone's interested.
-- Ron Davis (email@example.com), March 13, 1999.
Hi Dean, yeah, I should have mentioned the effects of a long draw on a shallow-cycle battery, but wasn't sure of the type of cells he was using - thanks for responding. I disagree with your statement re: L-16's... 48 Ah @ 4A would use up 192 A/h, equal to about a 60% discharge. That's a lot, even for an L-16, but it could be done with no permanent harm to the cells.
-- sparks (firstname.lastname@example.org), March 13, 1999.
Nice to find this thread prior to sinking funds into one of these find devices.
A couple of thoughts to add. Maybe increase the insulation with another couple of inches of styrofoam panelings (careful not to block any airflow ports...); keep the device in as cool a location as possible to give it the maximum temp range to work with; and finally put it on a mechanical clock timer, say 1 hour on then 2 or 3 hours off? Need to play with the numbers to find out what kind of temperature change rate would be encountered, then adjust the on_off cycle accordingly. This would be better than continous running me thinks...
-- j (email@example.com), March 13, 1999.
I read on one forum where someone was going to experiment with a woodburning refrigerator. Based on the same principle as the gas burning refrigerators. Evidently it would not need continuous heat. Not sure what ever happened with it.
-- (firstname.lastname@example.org), March 13, 1999.
The modlel that I purchased is the Coleman. It is one of the newer units that has a thermostat. Therefore it will not need to operate all the time like the older models. I think with the added insulation idea, and the thermostat still makes this a great idea.
-- Bugs Bunny (email@example.com), March 13, 1999.
Good thinking, j and Bugs. Putting it in an oversized wooden box made specifically for the purpose, and superinsulating it with many inches of foam insulation, plus a door on top of the box (insulated too) would help a great deal. I wasn't aware that the newer units had thermostats - combined with a super-insulation scheme, it would certainly use far less energy.
-- sparks (firstname.lastname@example.org), March 14, 1999.
Check that it opens from the top - you said "cooler" type so it might.
If a regular refrigerator door opens, all the cold air literally "spills" out. Warm air from the room replaces it, so the warm mus tbe cooled off after the door shuts. A door that allows opening "up" keeps the cold (dense) air in the fridge when the door is opened.
Old-time freezers were more effective with their top-opening doors. (Changes in compressor design and insulation make up for some of the differences, but when kids open the door - the air still flows out until they shut again.
-- Robert A. Cook, P.E. (Kennesaw, GA) (email@example.com), March 14, 1999.