My SOP for rehabilitating an older vehicle:
Requirement #1: A new or know-good battery.
Requirement #2: New battery cables. (Two new ones, one for positive/supply and one for negative/ground,)
Step #1: Clean battery posts and inside of battery terminals. (Bright shiny metal = clean connection, dull oxidized metal = unreliable connection.)
Step #2: Apply a small amount of dielectric grease to battery posts and inside of battery terminals. (As with many things in life, a little is good, a lot is not.)
Step #3: Place battery terminals on battery posts and tighten well. (If you can wiggle the battery terminal, even a little bit with lots of effort, they ain't tight enough.
Step #4: Repeat steps 1 though 4 with the other ends of the new battery cables.
At this point, you're ready to continue with the rehabilitation.
Anything you do before following this SOP is will very likely result in wasted time and effort.
Note: I really, really hate solving the same problem more than once ... so, the result is this SOP.
