Just wondering before I mess it up.
Well, it'll just let the smoke out once...
There is a label on the power jack that says “5V”. A 12 V supply will result in undesirable consequences.
CircuitCo has a 12 Volt to 5 Volt linear regulator CAPE for the BBB, that will allow you to put 12 Volts into the CAPE, and 5 Volts gets sent to the BBB.
Of course, it might be cheaper to just buy a 5V Wall-Wart.
i been using a cell phone 700ma usb charger on one of my beagles
works well but you cant flash using it
i got a bunch of them from old cell phones