I don't know how it does it ... but I do know it's *only* the Delco internal regulator that does it.
It also helps that I have my alternator wired correctly! Most people take the #2 wire and piggy-back it to the BAT connection -- that's the wire that reads how much voltage your system is getting from the battery. But doing it that way is just reading the battery itself. I've wired mine to a terminal on my firewall where all my equipment it getting juice from the battery -- see this picture:
http://alanhorvath.com/54chevy/chevypics/wiring_1.jpgI installed the Delco 12si with a Delco internal regulator via advice from Mark at MadElectrical.com ... after noticing that my voltage gauge was dropping down to 11 Volts, from 14 volts, I called him and he asked me if it was a hot day. I said, yes ... and he said "That's great, Alan! That means you have the Delco internal regulator!" Then he explained it to me and I was amazed because I had never heard anyone talk about that before. It sure is a smart feature.
