Previously, we had discussed using a Transpo "adjustable" voltage regulator, on W124 and W201 cars that did not put out 14.5V even when new, esp. for Optima and other types of "main-free" batteries.

I ran across this site (http://www.detomaso.nu/~thomast/alternator/) that uses an inexpensive dioded across the regulator and alternator-body ground to achieve the same thing.

What do you think (Hank, Al, etc.?)

:-) neil
1988 360TE AMG
1993 500E

At dealer we always used the 80A alternator from the 1990 & later 300E's.

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The diode really has to go into the "field" circuit of the alternator to work that way. It makes the regulator think that the voltage is .5 volts lower than it really is, so the alternator puts out .5 more volts (or whatever the amount of the voltage drop across the diode is).

Note that in the ground wire the diode could heat up pretty radically!