I designed a driver for the Fenix that will drive the Lux at 550 mA @ 3.25 volts from a NIMH AA cell. That's right, 1.7+ watts to the Lux. This is almost double the power the stock circuit drives the Lux at. The MM driver draws 1.8+ amps from the cell giving the Fenix a runtime of over an hour with a super bright output. The driver is about 80% efficient. This is very good considering the low voltage of a single NIMH or Lithium 1.5V cell. The driver is well over designed to handle the extra power and will give a lifetime of reliable service.