How to configure Raspberry Pi in my car

Question

I have a plan to put a Raspberry Pi in my center console of my 2012 Nissan Maxima. I'm new to Raspberry Pi, but have experience with technology of this sort. In the center of my car, I have a:

• USB charging port
• RCA "Phono" Yellow White Red (white red for each side of car, yellow feeds into monitor of car for video)
• 12 V auxiliary power outlet (I believe this is the right name for it)

Again, I am new to the Raspberry Pi, so I'm not entirely sure how they operate, but between the USB charging port and the 12V auxiliary power outlet, that should be enough to power the Raspberry Pi. From here, I will connect a simple power bank between the Raspberry Pi and the power source so my Raspberry Pi has enough time to do a proper shutdown after I turn my car off. Then, hopefully, I will be able to install navigation software on the Raspberry Pi, and connect it via the Internet through my phone (either by Bluetooth or WiFi).

To sum my problems up...

1. What power source (USB charging port or 12 V auxiliary power outlet) am I going to need to use for my Raspberry Pi? (If the answer is the 12 V auxiliary power outlet, what adapters will I need?)
2. Do I need a power bank for proper shutdowns? Or should this not be a concern?
3. How do I properly hookup the RCA Yellow White Red Phono connections to my Raspberry Pi?

Additionally, please tell me if there is a better way to set this up, even if its a different approach. My resources were stated at the start of the question, and I'm willing to buy any equipment needed.

Answer 1

1. Powering the Raspberry Pi

You should supply your Raspberry Pi via its microUSB port. It takes 5V and you should make sure it can draw up to 2A - that should be sufficient, if you don't plug in too much peripherals like keyboards, USB drives etc.

Using your 12V auxiliary power outlet, you would need a car-to-USB-adapter and a USB-to-microUSB-cable. However, your cars auxiliary power outlet will probably be turned off whenever you disable your ignition, causing the Raspberry Pi to crash. In this setting, you would need a power bank.

Using an internal power supply that does not die together with an ignition stop, you would not have to use a power bank. Examples of such power supply is the radio clock's power supply, indoor lights or instrumentation. However, this would require rewiring (minor) parts of your cars electric system which should only be done if you know what you are doing.

2. Shutting down

You should always shut down your Raspberry Pi properly, meaning shutting it down using a software command which stops the operating system from executing. If you don't do this, you might corrupt your SD card. Once your Raspberry Pi is shut down this way, it would only restart after it is disconnected and then reconnected from/to its power supply.

In the power bank case, you would probably want a (software) switch to shut it down, a (hardware) switch to shut it off when you leave your car and turn it on, when you enter it again.

In the internal power supply scenario, you could try using another internal power supply that does turn off without ignition to trigger a shutdown via the GPIO once it stops. To connect and disconnect the continuous power supply, you could then probably use a relais switch controlled by your door lock system.

3. A/V-Out

Apparently, you can use the "audio" jack to grab a video signal as well. Furthermore, you could solder your RCA cables onto the pi. And, the probably cleanest though most expensive solution, you can get HDMI to Composite adapters (they exist in both ways), too.

Answer 2

4 things:

• proper shutdown: what is meant by "proper shutdown" in @Fantilein's answer is what we call a "software shutdown." You need to issue a "shutdown" command in the OS, either via the command-line or the GUI so that the OS shuts down completely. This only takes a few seconds, so not a lot of power is needed there.
• power: the Pi runs on 5V but can draw up to 2 amps. Some USB ports are limited to 0.5 amps, so measure how much current yours can output.
• power bank: you already have a powerbank in the car, it's your main battery. Now, as has been pointed out, the USB port of your car may poweroff when the ignition is turned off, but not all cars behave this way. I own 3 cars, 1 of them shuts it off, the other 2 don't. If your car doesn't shut it off, no need for a power bank, just make sure you power the Pi off or it will slowly drain your car battery. If your USB powers off with the key off, you can always rewire the USB port so it always draws from the battery, or steal power from something else that does (4-way blinkers are my favourite, your radio's clock is always getting power too).
• powering back up: the Raspberry Pi is a little bit weird this way. After a shutdown, the absolute only way to power back up is to cycle the power. So, regardless of whether the USB port is continuously powered or if you have a power bank, the easiest way to power cycle is to add a on/off switch between the USB port and the Pi. So your shutdown routine will be to issue the shutdown command, wait a few seconds for the Pi to shutdown, then flip your switch to off (even after sutdown, the Pi still draws power. Shutdown only shuts the software down, the hardware stays on until you pull the plug.)