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 up 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 (O) Leave a message.
linuxdude AT techstarship.com
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