stupid question?
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Joined: May 2001
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From: saskatoon,saskatchewan,canada
stupid question?
does the alternator get harder to spin the more electrical load is placed on it?
reason why asking is idle rpm drops slighty when elec fan kicks in.
reason why asking is idle rpm drops slighty when elec fan kicks in.
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Joined: Jul 2000
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From: Warrenton, VA U.S.A.
Stupid answer: Yes.
Seriously, your assumption is 100% correct. When I turn one fan on (I can do it manually) at idle, the start-up current (~50 amperes at 14.2 volts for less than 0.5 seconds, then ~15 amperes run-current at 14.2 volts) puts such a load on the alternator that it will lower my idle speed to 400-500 RPM. I don't know the exact RPM's it drops to, but sometimes it loads the engine so much that I think the engine is going to die! Of course, at idle, the ECM compensates for engine speed based on load (via the IAC switch), but this happens so fast (less than a second) that it doesn't give the ECM/IAC enough time to compensate immediately. This is one reason why I do not have both fans wired to operate simultaneously (the other reasons are because it is not necessary 99% of the time for me and to reduce wear on one of the fans).
Actually, when this happens, you'll know that your alternator is working. Maybe not 100% correctly, but at least you'll know that it is putting out [and drawing!] energy. Perhaps I should have said "converting" energy - mechanical to electrical.
Good observation.
By the way, I have two L.E.D.'s in my instrument panel that show me when a fan is operating (I have two fans). This will let me know quickly if I have a problem with a fan(s).
Seriously, your assumption is 100% correct. When I turn one fan on (I can do it manually) at idle, the start-up current (~50 amperes at 14.2 volts for less than 0.5 seconds, then ~15 amperes run-current at 14.2 volts) puts such a load on the alternator that it will lower my idle speed to 400-500 RPM. I don't know the exact RPM's it drops to, but sometimes it loads the engine so much that I think the engine is going to die! Of course, at idle, the ECM compensates for engine speed based on load (via the IAC switch), but this happens so fast (less than a second) that it doesn't give the ECM/IAC enough time to compensate immediately. This is one reason why I do not have both fans wired to operate simultaneously (the other reasons are because it is not necessary 99% of the time for me and to reduce wear on one of the fans).
Actually, when this happens, you'll know that your alternator is working. Maybe not 100% correctly, but at least you'll know that it is putting out [and drawing!] energy. Perhaps I should have said "converting" energy - mechanical to electrical.
Good observation.
By the way, I have two L.E.D.'s in my instrument panel that show me when a fan is operating (I have two fans). This will let me know quickly if I have a problem with a fan(s).
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Joined: Mar 2001
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From: Montreal, Quebec, Canada
Car: 1987 Camaro
Engine: 1986 350
Transmission: T-5 NWC
no brother is not a stupid question and good stuart is right too,
to add to that let me give you an example, in aviation is the same, only much bigger, say...the normal operation of the generators on jetliners require the flight engineer or mechanic or pilot (whoever is doing it) to switch-off the heavy current eaters such as galleys (the ovens are real bad)and electric powered pumps "before" switching power source to the engine driven generators or...
BUUUMMM!!!your gen shaft is cut, loose all power and a big **** is coming real fast to you, we messure the load (the effort to work) on an aircraft generator in KVAR (KILO VOLTS AMPERE REACTIVE) and you can also monitor their temp. they go real hot, the point is that is the same for all only different sizes.
yours...
fernando
------------------
third gen muscle power is the only thing that can match the power of flight...
to add to that let me give you an example, in aviation is the same, only much bigger, say...the normal operation of the generators on jetliners require the flight engineer or mechanic or pilot (whoever is doing it) to switch-off the heavy current eaters such as galleys (the ovens are real bad)and electric powered pumps "before" switching power source to the engine driven generators or...
BUUUMMM!!!your gen shaft is cut, loose all power and a big **** is coming real fast to you, we messure the load (the effort to work) on an aircraft generator in KVAR (KILO VOLTS AMPERE REACTIVE) and you can also monitor their temp. they go real hot, the point is that is the same for all only different sizes.
yours...
fernando
------------------
third gen muscle power is the only thing that can match the power of flight...
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