Take this as an interim reply untill someone more authorative answers your post.
My guess is that your voltage regulator (which is mounted on the back of your altenator) is starting to go bad... in that it is overcharging your battery by allowing too high a voltage to pass from your altenator. Simply replace the voltage regulator... and not the altenator.
1993 190E 2.3
2000 Toyota 4x4 Tundra