Charles;

It sounds like that cable you had to run from alt to battery neg is a band-aid and masking another issue! Normally, the negative connection is completed by alt case and bracketry and the grounding strap which hops from engine block to frame in the general area of the bell housing, exhaust side...if you needed to add a separate cable from alt frame to bat neg, that suggests this path or its connections (or battery chassis connection) have a problem...I'd check it out (meaning inspect, and make clean and tight...and use ACZP to protect!) because that path carries charging and starting current, and a poor connection anywhere in the path means that part of those currents is likely traveling an alternate (unpredictable and probably undesirable) path (not good)...poor negative connection at the alt may also result in overcharging the battery as any voltage drop at ground may be added to the voltage regulator reference (also not good)...I highly recommend checking for and sorting your poor chassis connections!

Good Hunting!