[Jeff Wagg]

I installed a CarPlay radio system from Crutchfield. Pretty straightforward, works and sounds great... but our odd little cars have no accessory switch on the ignition.

Has anyone overcome the problem of wanting to listen to an aftermarket radio without having the ignition on?

The radio (Pioneer AppRadio 4 SPH‑DA120) does NOT have a power switch. It's meant to always be on if it receives voltage from the (non-existent) accessory position, or the ON position.

I suppose I could run a simple switch to provide voltage to the accessory wire. Hmm, maybe with a timer so as not to accidentally kill the tiny battery.

 

[vadsoom]

I also ran into this dilemma. My solution: wire a latching relay into the only unused switch on the button bank to power the radio when the car is not running. I added a 10 amp diode to keep the radio from back feeding the aux power circuit. Later, I added a 1 hour timer to keep the battery from being drained is inadvertently left on.