Classic symptom of dirty battery cable terminals- - - - -there's too much resistance to carry starter current but enough of a connection to power the small current draw items like dash lights or gauges. As soon as a starter current demand hits, it wipes out everything.
Pull both battery cable terminals, and do a thorough cleaning of the battery posts and the inside of the cables with a wire brush tool designed for the purpose. I've gotten by with scraping the inside of the cable terminal with a pocketknife and using a wire scrub brush on the posts, but the dedicated tool does a better job. Once the terminals are reconnected tightly, put a little Vaseline or wheel bearing grease on the outside of the terminal to retard corrosion.
Jerry
