Please see http://www.mausberrycircuits.com once campaign has completed.
Hello! After many requests stemming from my desktop Pi power switch, I have created a power supply for the Raspberry Pi which senses your car's ignition. It has a built-in 12/14V to 5V step-down converter and when you turn the ignition off, the supply communicates with the Pi via two GPIO pins and tells it to start shutting down. A microcontroller handles all logic operations like the desktop switch. The power supply maintains power until the Pi has safely finished the boot-down process and then removes power. The supply is most easily installed by connecting to 3 wires behind your radio: the +12V(car battery), ground and ACC (switched ignition) wires.
The power supply also has a jumper on the PCB that allows the user two options - you can either have boot-down begin every time you turn your car off OR you can have the power supply wait 20minutes before telling the Pi to shut down. This is useful if you make frequent stops and don't want to wait for the Pi to boot every time you restart your car. The power supply will also automatically remove power after 4 hours of the ignition being off to prevent a stalled Pi from draining your car battery.
I will be providing two versions - a 2amp power supply and a 3amp power supply each with the option of single or dual USB ports on board. The USB ports are power only, no data. I will have a stretch goal of an ONBOARD 3-port USB hub as well!
I have also programmed the power supply such that if you switch the ignition on and off 4 times in rapid succession (you don't have to actually start the car) it will pull power from a frozen Pi. This is useful if you have your Pi mounted in a hidden location or enclosure.
The power supply has a built in resettable fuse for protection.
Risks and challenges
The biggest challenge will most likely be for non-auto savvy users to wire the power supply into their car. If the user has any experience with installing a car radio then this will be no problem. I will do my best for other users to provide basic installation diagrams and instructions.Learn about accountability on Kickstarter
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