OK. Alternator belt is tight, I DID find some badly corroded wires underneath the battery tray (116) and replaced them, I was hoping it was my problem.

Fully charged the battery..Here's the test results

after charge, the battery disconnected was giving 13.8V
running, at Park idle alternator was putting out 14.1V great! not so. As teh engine warmed up the RPM's came down and so did the voltages. 14.0-> 13.8 -> 13.0
warmed up, idling, it held 13.0. the INSTANT I put it in drive and the RPM dropped to 550RPM voltage dropped off and sat at 12.3V. idle was smooth and no misses with no additional loads on the alternator. the moment I turned my headlamps on, battery voltage dropped to 12, Fog lamps, then it developed a miss and it started idling erratically.. When I was idling it cold, as the RPM and voltage dropped I revved the engine and it would come back up to 14, but back down as soon as I let off the throttle.

With the loads on and the battery voltage down at around 12 I revved the engine to approx 2000RPM and the voltage did not go up AT ALL. If it were raining, and cold, and dark, that car would die within probably a couple hours of driving around.

turn off loads, rev the engine up and idle smooths out and voltage comes back up, but won't stay up.....

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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