Simple re-wiring

67Dart273 said
Take a test lamp, unhook the ground cable and hook the battery in series with the test lamp to ground.

Start pulling fuses one by one.

You have a modern stereo/ radio with "memory keep alive?" How about a separate high power amp?

If pulling the fuses doesn't drop the load, unhook the main alternator output stud. You might have a leaky diode, or the internal radio capacitor (condenser) may be leaky

What do you mean by "ignition switch wire?"

Check the circuits that should be cold when the switch is off by pulling the fuse. Bridge the fuse clamps in the box with the leads of a volt meter or LVCT (aka multi-meter). If you get a reading when logic tells you there should be no power, dig in.

IMHO the worst offenders are alarm systems, followed by electronically tuned radios that save station selections and have a clock function.