bgd73 Posted October 27, 2006 Share Posted October 27, 2006 I searched when I thought my cars overthought engine draining a/c was all done forever for a 12/24 volt system you may see on the roofs of campers and trucks. I think the link below is what I am thinking about, and can testify that it really works on a 24volt (powerfully!), but my question is - will it on 12? particularly the 39 amp version. I was even thinking ahead about a second alternator, but fear the second ground interference. It is a cold fall where I am right now, but thinking ahead for an old sube without a/c.I want to be able to take my car anywhere anytime. I remembered My DL manual steering no a/c gave me symptoms of a heatstroke, after several hours of slow crawling on hot tarmac. and get this one GD: The EGR was 90% percent of top end heat problem! But anyway.. I don't ever want to be in a traffic jam in the 5 o'clock sun at 95 degrees ever again.without a/c. My wrecked Loyale was perfect only for the last half of summer with factory a/c. I am sad.If an engine can turn that crazy inefficient setup- what can electricity do? Again, I only saw the 24v in action and it was quite impressive for a tractor trailer with large bunk. The 12 proportianately would be nice for a little sube wagon. http://www.sailgb.com/p/12v_air_conditioners/ Link to comment Share on other sites More sharing options...
DaveT Posted October 27, 2006 Share Posted October 27, 2006 I don't ever want to be in a traffic jam in the 5 o'clock sun at 95 degrees ever again.without a/c. A few things: The stock factory AC is about 15,000 BTU. The 39A camper one is only 9000BTU. If you want it to run while stuck in traffic, you will need a huge battery, since the alternator will not put out that kind of power at idle. Converting rotational energy into electrical energy to then turn electrical energy into rotational energy will use more power than keeping it rotational all the way through. When the factory system gets ahead of the cooling load, it releases the clutch on the compressor, drawing no power. Link to comment Share on other sites More sharing options...
daeron Posted October 28, 2006 Share Posted October 28, 2006 yah man, a watt, is a watt, is a watt, whether it is a watt of rotational energy spinning your compressor, or spinning your alternator(s?) under heavy load, and any conversion from electrical to kinetic energy is wasteful.... Cooling capacity aside, you would LOSE engine power with this system compared to the stock system..... When youre driving down the road, radio and AC off, middle of the day, your alternator isnt doing much charging... and it is putting less physical load on the engine. At night time, in the rain, with front and read windshield wipers going, and fog lights, and the radio on, and defoggers going, and youve got the maplight on to see where the hell youve gotten yourself... the alternator is putting out a high charge, and taking a significant bite out of your engine's available power. Magnets, you know.. when the alt is not excited, the field magnets arent energized and there is no resistance to the rotation of the armature. When the thing is energized, there is a great resistance to the rotation of the armature. You cant get around it, the AC is going to demand power. Im not sure what the conversaion factor is, but a BTU IS translatable into a watt, and into a horsepower figure. stupid, intractable, damnable Law of Conservation of Energy. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted October 28, 2006 Share Posted October 28, 2006 I'm a generator mechanic, and I can tell you that the more times you convert from mechanical to electrical energy, the more you will lose. It's a basic principle of the universe called entropy (which is one aspect of the 2nd law of thermodynamics.... Daeron mentioned the 1st law, but the 2nd is the most important for this conversation). You will always expend more energy than you get back out. Converting from mechanical to electric, and then back to mechanical again is always going to be a loss. Better to just use the mechanical you already had - that's what the AC compressor is for. GD Link to comment Share on other sites More sharing options...
daeron Posted October 28, 2006 Share Posted October 28, 2006 yah, i posted the link before i read it myself Ive always filed all that stuff away under "law of conservation of smuh" where smuh == energy or mass as it may take form in the corporeal universe. my brain is more than odd.. im beginning to think is prime.... indivisible by anything other than itself and 1.... Link to comment Share on other sites More sharing options...
GeneralDisorder Posted October 28, 2006 Share Posted October 28, 2006 No - your point as you presented it was totally valid, but I wanted to also point out that while a closed system can't *increase* it's energy, it's also true that it can't *not* decrease it either. It must decrease acording to law #2 (which really isn't a law, because it *could* be broken, it just never is in practice. It's one of the few [if not the only] laws of physics that's really a "statistical law" - it's not always true - just in the vast majority of cases). You lose most of the energy to friction and heat durring each conversion. GD Link to comment Share on other sites More sharing options...
daeron Posted October 28, 2006 Share Posted October 28, 2006 heh, threadjacked? sorry bgd yah i gotcha.. i was just saying i have always used the one term as a label for all that hunk of knowledge.. in a similar manner i call "heisenberg uncertainty principle" on anything that might fall under the wide umbrella of "chaos theory" anyhow, i was trying to find a way of stating (in fewer words, and with more humour) that i had wrapped all that knowledge into a box and labeled it, and just reached out my label, looked it up on wikipedia, and used it as a link for a punchline not even knowing offhand which of the specific laws i was quoting; i had mashed them into one in my head, because in my mind its all about grand unification anyhow. Entropy is one of those tricky words that has a very concrete definition in the material, techinical world, and yet a totally different one philosophically.... entropy, philosophically is more like the opposite of chaos.. an ultimately achieved state of uniformity. another good one is emulsify, ask a chemist and a college english teacher to define that term and compare the definitions you get. HAH! okay, sorry folks, im going to bed now. my sleep deprivation has gone on long enough, and im not going to subject you all to it any more! Link to comment Share on other sites More sharing options...
bgd73 Posted October 28, 2006 Author Share Posted October 28, 2006 The increase in the internal energy of a thermodynamic system is equal to the amount of heat energy added to the system minus the work done by the system on the surroundings. I like thermodynamics. Could I sum it up with bgd73's law of thermodynamics: "If you have enough power to create another energy from an even greater energy source, Just Do It." I don't want to mess with lines and hoses and noisy clutch. and heat generated for the EA82 engine already straining.A nice tight system with a smart electric pump like my house a/c running on a 10 amp shared circuit at 115 volts(+/-) without even flickering lights for a total of 11,500 btu.All on its own, its heat in a different locale than a car would have it. A 9000btu tight electrical system a/c would be a quick alternative for nearly 2500 dollars and some roof space taken. I wouldn't ever spend it, but I really like the idea of it. Link to comment Share on other sites More sharing options...
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