I recently had a problem with the alternator not charging my battery, and went through hell trying to figure it out. Battery voltage hung around 12.9-12.5 volts after replacing solenoid, voltage reg. and alternator. I saw other people had this problem so I thought I'd share my solution. I found that the A terminal on the voltage regulator had been bypassed and was connected to the F terminal. This was effectively bypassing the voltage reg. and not letting the alternator charge. So if you have this issue, check the connector to your voltage reg. and make sure that you have all four connections.