I am building battery powered Raspberry Pi offline Wikipedia web servers for educational use in rural South Africa. The Pi is set up as an Access Point and are accessed by students with wifi cell phones. They run Rachel software (rachel.worldpossible.org). The batteries are charged once a day using solar panels. There is no other power source.
First, I want the teachers to be able to start up and shut down the Pi gracefully by pushing a button. Second, I would like the Pi to shut down cleanly when the battery runs out. I have accomplished the first goal using an ATXRaspi and it works great. I was wondering if I could solve the second problem using the MightyBoost.
I assume I could connect the main solar charged battery to the MightBoost input and would then need to add a more or less permanent second small Lipo backup battery to the battery connection. I also assume the MightyBoost would keep the small Lipo backup battery charged. The MightyBoost would then be configured to shut down the Pi when the main battery power was most. Does this arrangement sound feasible? What is the minimum size of the Lipo battery if I assume the Pi B+ draws about 500mA? This is a stretch, but is there a way to set this up using only the single solar charged main battery and no backup battery, but still get a graceful shutdown when the main battery runs out?
As part of this project I am going to create a small PCB that mounts on top of the 40 pin GPIO header, has headers on top of the PCB to attach an ATXRaspi or MightyBoost, and also has a Button/LED mounted on the PCB that will stick through the top of the case.
Anything above 500mAh will work, I would recommend at least 1000mAh to get any kind of decent usage out of it.
Remember to duplicate the ATXRaspi functionality, or customize it, you will need to pair it with a Moteino (no radio needed unless you want to control MBoost remotely).
The INPUT side (either uUSB, 2.1mm jack, or header pins) require 5V to keep the load running and the battery charged. Please see the specs and requirements of MightyBoost here: www.lowpowerlab.com/mightyboost
Thanks. I guess I didn't read carefully enough and realize this needs a Moteino to duplicate the ATXRaspi features. For my application, I'll just stick with the ATXRaspi and create a daughterboard to connect it to the Pi.
Never knew about battery boosting power