I am trying to figure a good setup for switching and power supply solution for the Raspi 2. I did some reading on the mighyboost with the moteino, which seems ideal.
1) Which of the following battery would be best and or good enough to either keep the raspi running just to shut it down immediately in the event of a power lost, as well as which is best for continued usage in the event of a power lost.
https://www.adafruit.com/products/1781
https://www.adafruit.com/products/2011
2) Lets say the setup is configured to shut down the pi immediately if there's a power lost from the wall power supply using the battery to keep it running just long enough to perform the shut down, and the power from the wall power supply cuts out and comes back in either immediately or 2 to 3 seconds after, what will happen, will the pi continue its shout down and then has to be start again?
3) Is it possible to set this up so that the pi will not be able to turn on using the switch and the battery connected if there's no power from the wall?
Ultimately, what i want to achieve is 2 different setup, one where the battery is only use really to shut down the pi clean in the event of power lost from the wall, and not able to start the pi with only the battery as power source available. This is to protect the SD card really.
The other setup i suspect is already possible and is the default, which is the pi can be power on with or without power supply from the wall as long as a battery is connected, and perhaps can shut down the pi once the battery reaches a certain level to avoid the pi from losing power and not shutting down the pi once the battery goes dead, please correct me if i am wrong about this.
The power button is an input to the Moteino which will control the output of the MightyBoost. So you have complete control of when to shutdown or cut power.
The sample sketch I provide is just a guide, and you can modify it to change the battery threshold or simply shutdown as soon as power is lost. Right now it will only request a shutdown to the Pi if the battery discharges below a certain voltage but it will not automatically power it ON again, a button press is required. You can change that if you want in the sketch, up to you.
The 2000mAh will probably be OK to keep power for a shorter period of time, I would recommend 2500mAh for a longer period. I've done my own test with a 2500mAh and it could power an older Pi for up to 1 hour before it reached 3.3V.
Hi Felix,
Thanks for your informative reply, much appreciated.
Hi,
I am trying try find the schematic for the mighty boost, but don't see it, can you please provide the correct link, i was able to find the moteino but not the mighty boost.
Everything that is available is already posted on the MBoost page here (http://lowpowerlab.com/mightyboost).