Cananyonesend mea picture of the 2000 S500 fuse chart. I have a problem keeping my battery charged while the vehicle is running. Thought it may be the alternator, but someone said there may be a relay (fuse) that went out...is this possible? if so, where is the relay for the alternator??? Thanks to anyone out there!

 

Simple.
Just connect a (good) voltmeter to the battery terminals.
Engine off you should have a reading > 12.5 volts. 12.5 is the ABSOLUTE minimum.
Engine running (lets say 1500 revs) you should have 14v / 14.5v).

Subject to results you have / do not have a problem with the alternator.

The voltage regulator is part of the alternator circuit. VR's do give trouble especially when the car has been jump started etc.

In the "old days" voltage regulation was achieved thru the use of a number of relays but no longer.