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Powering a PI (and accessories) from a 12v 15A rail.

halkun

I'm getting together parts for a project that will put a Pi 3 with touch screen in my car. It's replacing the radio, but the 12v line that went to the radio has a 1A fuse, which is too low for the 2.4A power needed for the PI 3. However, under the radio is the cigarette lighter, which has a 15A fuse. Sadly, most of the 12v lighter to 5v USB adapters have a 1A limit. I'm going to need some kind of breakout that's going to power PI and it's various attachments.

 

Breaking down further -Things I need to power.

 

Raspberry Pi 3  - (5v 2.4A)

Touch Screen - ? (the pi powers it)

Pi Cam (Powered from Pi)

 

7 port USB hub (5v - 2A)

GPS module (Powers from USB hub)

External Webcam (Powers from USB hub)

 

What parts do you think will make something like this? I'll most likely be dong this in some perfboard. My guess is that I'll break out to:

-One USB (+5 and ground only @ 2.4 amps) to the  Pi/touchscreen complex and

-One wall wart "tube" power jack (5v  2A) to the USB hub.

 

Any ideas on a part list?

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  • 0

    Hi Joshua,

     

    My first thought is that you should continue to use the feed wire for the radio. You can change the fuse to a higher value of perhaps 3 Amps. If you use switching converters like the ones you mention this should be plenty of power. 3 Amps at 12 Volts is 36 Watts. Another good reason for using the Radio Power feed is that it may have some noise decoupling built in. This could provide a cleaner power source for the converters. Otherwise the power distribution that you mention should work for your application. Get good quality converters and you can add a couple capacitors, (1) 1000 uF at 16 V and (1) 100 nF across the outputs of the converters. This will protect the Pi from spikes and fluctuations.

     

    John

Reply
  • 0

    Hi Joshua,

     

    My first thought is that you should continue to use the feed wire for the radio. You can change the fuse to a higher value of perhaps 3 Amps. If you use switching converters like the ones you mention this should be plenty of power. 3 Amps at 12 Volts is 36 Watts. Another good reason for using the Radio Power feed is that it may have some noise decoupling built in. This could provide a cleaner power source for the converters. Otherwise the power distribution that you mention should work for your application. Get good quality converters and you can add a couple capacitors, (1) 1000 uF at 16 V and (1) 100 nF across the outputs of the converters. This will protect the Pi from spikes and fluctuations.

     

    John

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