Hmm...that could be useful. I'm not so much concerned with melting ice as I am preventing the inevitable total fogup of the windshield about a mile from home that happens if you don't let the car warm up. Allen B. ----- Original Message ----- From: David Ritchie Sent: 01/21/14 11:26 PM To: tech-chat Subject: Re: [tech-chat] Car defrosters
Harbor Freight sells a small plugin electric heater that is designed to set on your dash - 156 Watt. http://www.harborfreight.com/12-volt-auto-heater-defroster-with-light-61598.html Perhaps this would suffice. -- David On Tue, Jan 21, 2014 at 8:28 PM, Ron Frazier (TECHC) < [email protected] > wrote: On 1/17/2014 8:20 AM, Jim Lynch wrote: On 01/16/2014 10:49 AM, Allen Beddingfield wrote:This is my Facebook status this morning, but I thought I would throw it out here for people to discuss :) With all of our technology, why do we not yet have an instant-on source of heat for defrosters in cars? Sure, the manual in the car says that modern engines don't have to be warmed up, etc... what good is that if I still have to let the car sit for ten minutes to warm up the coolant enough to make the defroster blow warm air? Otherwise, the windshield and windows are just going to fog up completely about a mile from where you start? If the engine is running, couldn't we generate enough electricity to power a heater pointing at the windshield for long enough for the engine to warm up?!My guess is no. An idling engine doesn't put out all the current the the alternator can produce. I'll have to run the numbers but even if it's 15 amps (which I doubt) that's only 180 watts. Compare that to a space heater at 1500 watts. It would be a drop in the bucket. Install a tank heater and plug it in at night. The engine coolant will be warm in the morning and take less time to get up to temperature. You will get warm air from the vents right away, albeit not enough to do much warming of the car. Jim.I think Jim's right. Running a 1500 W heater electrically in the car would require 125 amps. Many cars have less than 100 amp alternators. I think my 81 Mercedes has a 55 amp alternator or something. I think more modern cars may have a 90 amp unit or something, but I'm not a mechanic. I don't think they have to be running at full speed, but they don't do much at idle as Jim said. I did put a space heater in a car once with an extension cord on a very cold morning when the car heater was malfunctioning. Even with that, it took 10 - 15 minutes to get the car toasty, although I think I had it on low power. Someone told me once that the climate control system of a car has to be as powerful as the heat pump on a small house. It takes a surprising amount of energy. Not only that, the manufacturers are under tremendous pressure to meet emissions requirements. My mechanic said they essentially build the car around the emissions system. So, I'm speculating that they want to warm u p the engine and catalytic converter as quickly as possible to minimize emissions rather than sending heat to the heater core. Having said that, it should be possible to send enough instant heat to the defroster to defrost and defog the window, maybe a 20 amp circuit providing 240 W or something. Sincerely, Ron -- (PS - If you email me and don't get a quick response, you might want to call on the phone. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new email messages very quickly.) Ron Frazier 770-205-9422 tel:770-205-9422 (O) Leave a message. linuxdude AT http://techstarship.com _______________________________________________ tech-chat mailing list [email protected] http://lists.linuxmoose.com/mailman/listinfo/tech-chat -- Allen Beddingfield [email protected]
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