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Old 11-09-2012, 04:04 PM   #12 (permalink)
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Originally Posted by ksa8907 View Post
perhaps they are using a different set/type of diodes to adjust how much voltage is being produced. alternators are pretty inefficient, maybe they've improved that as well.
In one of the papers about improving alternator efficiency that one can find linked to on this site, it's indicated that a big reason why alternators are not efficient is because they are designed to produce full voltage at idle speed, but typically the engine is operating at several times idle speed, and so the field current is very low. Obviously, the field coils themselves drain away a few percent of the power, the rectifiers (don't know what it's like on newer cars but...) seem to drain away a bit of voltage as well.

By allowing the alternator to produce power at higher voltages automatically boosts the efficiency
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