12v head unit switched power

[spatty99]

I want to add a bluetooth audio input adapter for my Sony CDX-HS70M stereo head unit (2008 212X). Ideally I would like to install a usb charging socket with volt readout (see amazon link below) in the existing audio input/phone cubby to power the bluetooth receiver only when the stereo is on (but not switched with the ignition).

Is there a way to grab switched 12v power only when the stereo is on?... Do I need a relay, and if so can someone link to something recommended on amazon? If a relay works, what would I connect to it? I'm already using the amp signal wire, would I use it too, or maybe the power antenna remote wire? The head unit manual is attached for reference.

Or is this overkill and full time 12v should be ok given the low power consumption (assuming I boat a minimum of once every 2 weeks)?

https://www.amazon.com/gp/product/B073NCMTQL/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1

 

[Adrian @ JB Solutions]

I would use a relay off the ignition switch. I wouldn't use the remote line, as they are only usually rated for 1 amp, though if used for relay it would be fine. However when you radio is off, so is charger.

I prefer to play it safe, so I would run a fresh 18 gauge line from the battery to the relay 87. USB power to 30, ground for relay and USB to 86, and ignition to 85.

 

[Mainah]

I would use a relay off the ignition switch. I wouldn't use the remote line, as they are only usually rated for 1 amp, though if used for relay it would be fine. However when you radio is off, so is charger.

I prefer to play it safe, so I would run a fresh 18 gauge line from the battery to the relay 87. USB power to 30, ground for relay and USB to 86, and ignition to 85.

I agree. If going with a dual 2.1 amp usb port another run is in order. Using the remote wire to trigger a relay will mean it is only on when the radio is. You could also trigger from ignition key on wire for just when the keys are on. I would go with a fused 16 awg run of tinned marine wire to be safe though.

 

[spatty99]

Thanks. So the amp trigger wire (ideal as far as when it is activated) is probably too low amperage (max 0.3A) if it's already signalling the amp. I forgot the antenna trigger wire would only activate when the radio is on, so that is out. Sounds like I'll pull from the ignition. Is it as simple as jumpering a switched power wire after the ignition key, plus adding the fuse and a ground? (I already made sure to get the proper tinned copper as part of my tower speaker install thanks to your previous posts).

 

[Mainah]

Thanks. So the amp trigger wire (ideal as far as when it is activated) is probably too low amperage (max 0.3A) if it's already signalling the amp. I forgot the antenna trigger wire would only activate when the radio is on, so that is out. Sounds like I'll pull from the ignition. Is it as simple as jumpering a switched power wire after the ignition key, plus adding the fuse and a ground? (I already made sure to get the proper tinned copper as part of my tower speaker install thanks to your previous posts).

I don't know about your model year but the separate yellow key on wires are good for 5-10 amps of direct connect accessories in 2015 plus. That said I still like dedicated runs. While at it you could use the key on to trigger the really connected to the input of a small fuse panel (assuming a large power run already at the helm) and then you would have a whole fuse panel worth of key on.

 

[Adrian @ JB Solutions]

Thanks. So the amp trigger wire (ideal as far as when it is activated) is probably too low amperage (max 0.3A) if it's already signalling the amp. I forgot the antenna trigger wire would only activate when the radio is on, so that is out. Sounds like I'll pull from the ignition. Is it as simple as jumpering a switched power wire after the ignition key, plus adding the fuse and a ground? (I already made sure to get the proper tinned copper as part of my tower speaker install thanks to your previous posts).

The relay is so easy to hook up, and running a 16 gauge wire is very easy... I would just play it safe.