This may be old stuff to some, but I'm still climbing this learning curve.
If a light he's built-in USB charging, is the charge current (not voltage), set by the charge control circuit in the light itself, or by the power supply?
Example: If a USB power supply capable of supplying 2A or more is used, will the full current available be applied to the cell being charged? Or, will the charge circuit in the light limit current to what is suitable for the cell?