I would like to power my raspberry pi 3 from an OTG supporting smartphone. I can get my hands on a Galaxy S3 for this purpose. My raspberry only uses the built-in wifi module, runs a loop and no usb nor hdmi devices are attached, so the pi is not drawing that much power.
From what I could find out, the raspberry should be drawing around 400 to 600mah.
Using google I couldn't find anyone who is trying to achieve the same.. did anyone try and achieve this? Any other advice?
edit: thanks for both answers, very useful. I will investigate more and might run a test. I will keep this question updated with any progress.