1985 300SD Alternator charging erratic , sometimes 11.4 at startup, usually goes to 13.0-13.3 after about 5 minutes running but sometimes goes that high at startup. After going to 13 it usually stays and vary slightly with load changes. Battery checked good at battery shop, alternator checked good but replaaced it anyway and conditions still seem about same. Car is not used for long runs lately and low battery started me checking system. Is the voltage behavior normal, Mercedes manuals not real clear. Thanks for any comments. Benny

You need to check the electrical connections. Particularly the connector that plugs into the alternator. Remove the connector, disconnect the battery and pry the back off the alt. connector. See that the wire is still crimped tightly to the spade lugs.

Good luck,

Benny,some the alt could be putting out voltage and not putting out amps,and that is what makes things happen.
good luck. Tom Brown
E300D 1995 123K

Thanks Larry and Tom, i drove the car about 75 miles yesterday and started at 12.8 went immediately to 13+ actually hit .8 after, after 15 minutes @ idle hit 11+ went for drive @ 13.3-.4 so feel good but will do more checks, yesterday shorlly after stops and restarting the "Preglow Timer Relay would chatter for 10-20 seconds, will chatter if lightly push on the front of the relay box try to research that today, wonder if that is related to the other voltage/low batt erratic recent history. Thanks for the comments/suggestions and will try respond with shorter accurate results. Thanks Benny
85 300SD 210k
90 300d 260,k
84 Jetta 500+kdiesel
81 VW PU 200+ diesel