How does a voltage regulator know that it needs to tell the alternator to put out (charge) to bring up the voltage in a battery that is low due to constant cranking???
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Electronic regulators use semiconductors (zener diodes and transistors) to control the alternator's output. Typically, the regulator controls the alternator by opening and closing the ground side of the field circuit. Doing so permits or obstructs current flow.What I Own: 1993 Mercury Grand Marquis GS
What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo -
Ok, but what about the old style analog regulators? What tells the vol reg that the battery needs to be charged?Comment
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It puts out voltage... if the battery needs more, it puts out more current to keep the voltage level up. Eventually the battery catches up and the current goes back to whatever the car is using.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
Originally posted by gadget73Originally posted by dmccaigComment
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The old ones used relays. When the voltage got above a certain point the relay would open and shut the alternator off. When it dropped it would close and turn back on. The difference between the open and closed voltage was reasonably small so the relay ended up fluttering on and off fairly rapidly and the average output voltage was basically right. If the gap got too big on the contact points the voltage got unstable or just wasn't right.
Those basically went away by the early 70s and they used transistors to do the same job. They also don't have to switch it on/off, they can provide a variable output so the voltage is more stable but its still varying the voltage on the stator to control the output.86 Lincoln Town Car (Galactica).
5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley
91 Lincoln Mark VII LSC grandpa spec white and cranberry
1984 Lincoln Continental TurboDiesel - rolls coal
Originally posted by phayzer5
I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousersComment
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Thain I remember around 1970 bringing the Stude to a shop in town that did only automotive electric, he took out his Sun Electric Book and adjusted those as you said relays. He also had one of the Sun distributor machines, he removed my Prestolite and set it up on that machine.......amazing piece of equipment.Comment
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