I have a few excellent external batteries, the kind with USB female connectors used to charge phones. Now I needed a high voltage 12V battery, or more specifically something in the 6V-28V interval to power a uRADMonitor A3 unit. The form factor was important too, as I needed something more compact, a portable power supply with DC output. With a 3D Printer and a CNC Router at hand, a quasi-professional…