My car has been having a weird issue which I can only attribute to a loose wire somewhere.

Once in awhile, the battery just stopped being part of the circuit. The car becomes unable to start and when started from a jump, runs off the alternator. Both the alternator and battery are good.

Some things I've noticed

When the brake pedal is pressed, or the high beams turned on, the circuit cuts out for a dip. Not enough to kill power, but enough to make the radio cut out.

The battery does not make a 12 volt circuit with the chassis either.

Thanks for any input.