PLEASE DO NOT DO this stupid "old wive's tale" so called test
FIRST it does not always prove anything, and second the surge / spike can hurt electronics
WHY this test does not work:
Situation A: Your alternator is actually working properly, but it's an older "round back." They sometimes don't "pick up" when idling slow. In this case you might remove the cable, and the thing might be turning too slowly to charge, and the engine dies. YOU think the charging system is "bad."
Situation B: Your alternator only puts out a "little." Maybe the stater is shorted, or all but one diod is bad. You remove the cable and the thing keeps right on running, and you think, "OK!!". BUT NOT The alternator may only be putting out a small amount
