Hello,
From what I understand, most of the board can handle 12v from the barrel jack. Outside of what is not handled by the 12v barrel jack, there is the 7.2v LiPo connector and the micro USB that can handle 5v.
From my experience, the USB Type A onboard should only be used to make other powered USB Hubs available for use. Then, you can achieve more peripheral usage and add actuators/sensors. I may be crossing a line here but the BBBlue and similar boards with the am335x SiP from Octavo can only handle so much mA of peripheral usage. For instance, you have 4 to 6mA per pin of use, right. So, with accumulations of mA onboard a running BBBlue from pin usage, there may be a HIGH LEVEL of mA that is not available for usage or this usage is HIGH and causes issues internally to the am335x.
In the SRM for the BBB, it seems on page 111, there is a listing of available mA that can be used per power pin.
So, if you go over this amount with that particular power pin, 3.3v or 5.0v, another should be used. I think the power out pin on the BBBlue for instance may be suitable for use for specific logics.
Seth
P.S. I think that like with P9_03 and P9_04 on the BBB, you have 250mA per pin at 3.3v. So, one would have to be reluctant to push over 500mA for use with both 3.3v pins in use on their respective locations. For instance, I have a sensor that draws 400mA, an example here, at 3.3v. Neither of those 3.3v pins can be used to power the board, sensor, or actuator in question. I would need another power source. I, as a hobbyist trying to understand everything while still learning, am currently thinking that there are not enough tutorials about the BBBlue but if you want to test to see your amperage, wattage, and/or voltage, one would just hook up some connectors, add power from the respective power supply connector(s), and then test. Right? With a DMM or a scope, you can gather a bunch of info. about your current (no pun intended) status of board usage.