electrical problems on my 99 SLS
 

when i start my car the battery is a 13.9 or around there. when i put it in drive and start to drive it jumps to 16.1 or 16.9 and then i get messages saying "battery not charging" or "service charging systems". then my radio changes like i turned off the bass and my a/c goes from blowing cold air to reg air. has anybody had issues like this before? i cleared all the codes and removed the battery for a few moments but that did not work. please, any help.

have the alternator tested and see if it its overcharging. sometimes when alternators go bad they wont charge and some will over charge. i had a car that caused my battery to leak due to it overcharging at 18 volts. So see if you can get the charging system tested and let us know what you come up with.

Alternator is controlled by PCM also. Check connections, and ground wires are clean and tight. Post codes that come back.