I own a Raspberry Pi and I'd like to use the OpenSprinkler Pi board to control my sprinkler irrigation.
OpenSprinkler Pi provides 5V to the RPi via GPIO pins as power source.
I know that failure to properly switch off the Raspberry Pi may corrupt the SD card and it will be necessary to re-image it.
That's why I'd like to use a DC step-down power supply module (like this http://www.ebay.it/itm/NEW-DC-12V-24V-4 ... 3f37183e63) + a truck battery (12V 120Ah 700A) as UPS just for the RPi.
The DC converter would be connect to the RPi via micro-USB.
I wonder what happens when you have 2 different power sources.
Is it a bad idea? Could it damage the RPi? Which is the best solution to keep the RPi always running, despite power outages, please?
Thanks for any advice!