I ran 12V directly from the battery via a fused 4-gauge wire to a 120-ampere relay on the driver’s side of the subwoofer panel. The relay is triggered by a voltage controlled switch, the APO3. The APO3 allows battery power to feed the rest of the panel so long as its voltage is above 12V, basically any time the car is running, or for about an hour after shutdown. Once the battery voltage falls below a preset threshold (I can set it for 13.05, 12.7, 12.1, or 11.8 volts) for a preset time (0, 5, 10, or 20 minutes), the 120A relay loses its trigger until the car is restarted and has run for a few seconds. The APO3 assures good battery health and no surprises as a result of a dead battery (been there, done that). From the relay, 12V travels to a second APO3 and a large fuse block. The second APO3 is set to power a small fuse block only when the car is running (voltage exceeds 13V). The small fuse block feeds the turn-on leads for the EQL and the subwoofer amplifier, which means the subwoofer system works only when the engine is running. The large fuse block feeds the subwoofer amplifier, an Icom ID-5100A VHF/UHF digital amateur radio transceiver, a “Super Booster” voltage regulator for the ID-5100A, a Raspberry Pi3 mini-computer w/DV-Mega (not pictured), and a 400W pure sine wave voltage inverter.
More Complex Than Required,