1) Check (test) your batter.
2) Replace the voltage regulator in your alernator. ($30.00, a screw driver and 10 minutes of yor time)
good luck

is it just screw-in and go! What is the voltage output at:
idle and and engine off.

My 89 260e reads 14+ at idle, 13+ engine off.

Shouldn't it be 12+ for both? Case of voltage regulator?

Thanks

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joel

Prayers bring forth enlightenment.

yes.2 screws.
idle:around 14 with daytime running light in Canada.14 is normal.
engine off:12.5 with alarm on and flashing red light(warning to would be carthief).you have to wait a while with engine off to drain off surface current(same after using charger or alternator charger),I am told.Immediately after shutting engine,my car read 12.85 or so.

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Tom 2010 C250 4-matic Sport (Canada)

Hey I have very little experience with alternators. Is there a guide anywhere to show the correct proccess on replacing a voltage regulator is it pretty simple? Just want to make sure I can handle it before i order the part. Thanks in advance.