not charging properly

Does it do the same when the hazzard flasher is engaged? If yes then take the rear bulbs out and retest using the brake stabbing technique.What this test is doing is differentiating between an electrical problem and a mechanical problem.If the problem persists with the bulbs out, it almost certainly is not related to the brake circuit. The proof would be to then disconnect the brake switch itself and or removing the brake fuse. I suppose you could start with removing the fuse first.
-Anyways... Suppose with the entire brake circuit disabled and the problem persisting, then I would suspect it has something to do with the flexing of the firewall, or the pedal mechanism snagging a supply wire. Since the engine cranks when the ignition is down, I would suspect the problem is after the ignition switch.That would be the blue wire.And as others have said, its time for the tug test. I usually pull the drivers seat out, so I can relax while messing around under the dash. Good hunting.