Sounds like dirty/loose battery cable connections. And/or bad connection where the ground cable hooks to the block, needs to be clean and without 6 coats of paint. The reason the charger starts it could be the clamping action of the jumper cables, OR the one wire is wired wrong and drained the battery since the last time you fired it. AND the "start" position of the switch could be bad, try jumping the solinoid directly. Now, how about some research, what is the battery voltage when it fails? No gauge? How about a volt meter? When a diode trio goes bad in an alternator it WILL drain the battery over night, and not every night. But is the battery drained? See above about research...............MP