@Shawk, I really like your idea with the automotive relay: Use the 32-pin harness -- where the optional console wireless charger accessory would normally draw its switched power -- as the relay trigger, then use the kick panel 25A power liftgate fuse as the source of relay main power.
Similar to your setup, I will hardwire a Blackvue B-124X battery to power a blackvue camera during parking mode. Hardwiring the B-124X battery requires a switched line and a ground. For my application, using an automotive relay has several advantages:
- Does not require running lines through the firewall. I'm also nervous about tapping the switched "Engine Control System" fuses in the engine bay.
- Taps a validated source of switched power. The Mazda wireless charger installation also uses this switched line for power, though the line itself is coming from an ECU (reference page 5 of attachment).
- Does not require removing the A-pillar trim to access the switched line underneath. The 24-pin harness under the trim is typically tapped for auto-dimming / homelink mirror installs. The A-pillar trim is held by two retention clips and a tether clip. The tether clip is designed to prevent the trim from flying after curtain ABS activation and is easily damaged during A-pillar trim removal.
- Will not potentially overload a switched line. The Blackvue B-124X battery has a max input current of 13.5A per the B-124X manual. Using the switched line instead as the relay trigger will not overload the switched line because minimal amperage is required to activate the relay. As a note, the max load on these switched interior lines is still unclear from what I gather. The wireless charger installation manual has a 3A fuse protecting the accessory (reference page 5 of attachment). The auto-dimming / homelink mirror may have an inline fuse of similar amperage protection.
- Taps an easily accessible, non-safety related, higher amperage fuse (25A) for main power. Use of the 25A power liftgate fuse at F7 of the interior kick panel fuse box will not compromise safety.
Thanks for the detailed write-ups, the great discussion, and for pioneering the way for newbies such as myself.
