Noob looking for some answers on low power options


I guess I should start by explaining my current set-up and what I want to achieve.

I live on a boat (kinda appropriate that my user profile shows that I’m fresh off the boat!) and run everything on 12v (either directly or with step-downs/inverters etc). My current media system is a NUC, 3 external HDs (externally powered), Alpine car stereo (4x 60w but realistically 15w per channel) and two speaker regions (down below and up on deck, four speakers each).

My issue is power consumption. I’d like to be able to leave everything on, but with the above running it’s consuming something in the region of 2.5 - 3 amps when on but not playing music.

I’ve been playing with a Pi recently and like the idea of running a headless unit, something that I control via smarphone connected to a local network, which is currently run by an old smartphone (to be replaced with one of those mini travel routers, 5v/1amp).

I’m interested to know what my options are. Can I by-pass the Alpine altogether? I’ve been looking at something like the Allo. Presumably the Pi and the Allo is all still pre-amp, so would it still need to go through the HU? What if I bought an amp? Any suggestions there?

And if I use the HDMI out, using an HDMI to RCA converter, do I get round the audio problems of the Pi, therefore by-passing the need for a DAC, or have I misunderstood something?

Appreciate any comments and feedback on this issue.

Thanks in advance.

Hi, thats quite an exceptional usage [emoji3]

I guess you have 2 separate domains to look at. The digital part and the analog part using the car audio equipment. Is it correct to assume that you turn the head unit off and would like to leave the rest (the digital part) always on?

Maybe you can use the GPIO pins of the Pi as a sort of ‘ignition’ car switch to turn the car headunit on and off.

In the digital part (is that part where you now use 30-35 watt ? Based on the 2.5-3 amps on 12v), are you using spinning disks? Are these going in sleep automatically when not used?

Moving to a Pi 3 with a single (usb) 2.5” HD could cut the power consumption in half.

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Hi Patrick, thanks for the reply.

The HU can be turned on and off via remote, which is quite convenient, especially as I use it for volume control. That said, I am thinking of removing the head unit completely because I never use it for CD or radio. It seems a bit overkill for my needs and I’m thinking of replacing it altogether with a 12v amp. However I imagine Alpine have packed all sorts of protectors and other stuff to make it all work well on 12v so I do worry that if I lose it and just put in an amp, what kind of protection and other things an HU does will I lose? Still, I imagine an amp will improve the quality of the music over an HU…

I’m unsure how the disks behave but I imagine they go to sleep when not in use. Certainly there is a delay when trying to access the video library as they boot up again from sleep. As you say, switching my music library from an externally powered HD to a USB-powered one would help. From what I understand a 4TB WD My Passport consumes 1.45W in idle and only 3.5W when running, compared to my current WD My Books, which are between 4W at idle and 9W in use.

The 35W comes from running the NUC (around 1.1amps at idle so possibly up to double under load), the HU (around the same when not playing music) and then three hard drives (two are for films and TV shows, so they can be discounted). As you say, a portable hard drive would help.

So onto a Pi with a DAC. How many watts does that pull in comparison? I’ve read a number of these Pi HATs perform better with 19v input, which isn’t really feasible on the boat (it is, but it’s not so practical). And would I benefit from a 12v amp, and how big should it be? My external speakers are 150W (internal are 60w).