Measured 1V drop from alternator bracket to body or battery when engine is running. Instead of the 14.3V the alternator is generating the battery got 13.3V only. Reason: connection of the ground cable to the alternator bracket was bad, the mating surfaces were corroded (see pictures). The cable is still good, there was no voltage drop over the cable. I cleaned the contact surface on the bracket and the cable lug, placed a tooth washer in between, tightened the screw and applied some dielectric grease. Result: no voltage drop anymore, the battery gets the full 14.3V from the alternator now and cranking is as fast as it should be. All problems got fixed for 50 cents.

 

that's much better than the starter current going through the wimpy braided rear ground cable.....

Note: dielectric grease is not conductive, but it is a good insulator and corrosion fighter...

 

Right, dielectric grease is put on after installation only as a protective layer.