Electrical Help - Dies After Start

[Danno55]

Hi, I have a 1971 350SL (4.5L). I started and moved the car a few days ago and it started and ran perfectly. I parked it and decided last night to move it back to its storage pad. It wouldn't start. I jumped it and as soon as I disconnected the jumpers it died. Tried again and same thing. I am new to troubleshooting the electrical system but I disconnected the battery and I'm charging it on my work bench. I disconnected and cleaned all the battery cable connections and reassembled. I took out the alternator and cleaned the plug contacts and put it back together and finally I pulled the voltage regulator off from the radiator support and cleaned up the contacts and reinstalled. I can't do much until the battery is charged but does anyone have any ideas of what to do next to troubleshoot? It just seems odd that it ran perfect then poof - doesn't run? Is there a charging circuit fuse or fusible link on this model? Thanks!