A circuit and method for monitoring the forward voltage for a plurality of LEDs in a battery powered device so that the gain in the LED driver circuit can be switched at a point that optimizes the energy provided by the battery. The invention provides for sensing each LED's voltage, VLED, and determining the maximum forward voltage, VLEDmax, between the plurality of LEDs. The invention uses the knowledge of VLEDmax in conjunction with VIN, converter output resistance and LED current, and current source/sink minimum headroom to switch from an initial gain to some higher gain just before the current sinks/sources would drop out, or from a higher gain to a lower gain in the event of the battery voltage going back to a voltage close to its initial value after being momentarily pulled down by a heavy load.