I am probably biting off more than I can chew, but I was looking at building a carputer to replace/supplement the existing system in my car. I don’t want to necessarily use my phone to so was looking at using
- Raspberry Pi 3
- USB GPS Receiver for location and navigation (or Waveshare 4G HAT for Raspberry Pi (LTE Cat-4/4G/3G/2G/GNSS if I want to add call capabilities)
- Mini USB Microphone for Voice Control
- Raspberry Pi UPS HAT - SKU: DFR0494
- 5 or 7 inch Touch Screen
My main questions are around powering the above via the car’s cigarette lighter socket. Can I
- connect the Raspberry Pi UPS HAT so that the battery charges and runs the PI and the screen simultaneously?
- use the Raspberry Pi UPS HAT to power down the Pi when the car’s power is turned off?
- Is there an alternative way to safely power down the Pi when the engine is turned off?
First, the cars power is 12V, the Pi UPS Hat supply is 4.5V to 5.5V. You will need a DC to DC convertor to bring the 12V to around 5V.
Assume you mean the car battery charges the 3.7V lithium. It is designed to do this.
The 3.7V lithium is only there to keep the system running when the 4.5V to 5.5V supply is removed, so the Pi can be told to shutdown.
Lithium batteries do not like the heat that can build up in a car stationary in the sun. They can catch fire. The system should be placed such that the lithium is not in direct sunlight, same as not leaving your phone on the dash of a car.
Thanks Jim, I’ll add a DC to DC Converter to my list.
Have a great day
A LiPo or battery is a great way to store energy but if you just need to be able to shutdown your Pi you could use a super cap: https://core-electronics.com.au/search/?q=super+capacitor
You’ll be pretty hard pressed finding an off the shelf setup to do exactly what you are after but I thought I would mention it as the operating range is twice that of a LiPo(-40 to 70C and -10 to 50C respectively, just note it will range for different batteries/caps).
Take a look at Anreas’s video: #133 Safe Shutdown for Raspberry Pi with Super Capacitors - YouTube