I fought through the same problem almost...I didn't have accessories not work but I kept having a battery light on the dash. I checked cables first, then replaced the voltage regulator (piece of cake), then finally replaced the alternator to get rid of the light. Maybe yours will be something else but I continually had the battery light lit on the dash until I replaced the alternator.

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83 300sd, 280K Blue/Blue Leather (~24mpg)
95 E300D, 150K Champaigne/Parchment(~33mpg)