I know what you mean, it drove me crazy as well. All can tell you is after this modification my lights are rock solid and my voltage gauge sits at about a perfect 13.8 volts. I know that the battery voltage is 12 volts but when the alternator is charging 13.8 is normal. You know, you can easily try this theory out buy running temporary wire from the battery or starter relay to the center wire on the regulator (terminal I in the diagram). Also make sure that the regulator has a good ground. This would be a temporary test and if it works you would need to install the relay.
