Patent ID: 8742673

Claim:
A method for correcting a measurement of usage of a light emitting diode (LED) lighting fixture component for determining the life expectancy of the LED, each LED having a junction to ambient thermal resistance (R θjA in ° C./W), the method comprising: in a microprocessor of a LED lighting fixture, over a period of time that the LED lighting fixture is being used to provide light; measuring, in the LED lighting fixture, a temperature (T A in ° C.) external to the component; measuring a power output (P D in W) supplied to or provided by the component; calculating an internal temperature of the component of the LED lighting fixture (T J in ° C.) based on the equation: T J =T A +(R θJA ×P D ); determining a multiplier as a function of the calculated internal temperature (T J in ° C.); and multiplying the period of time by the multiplier to provide a corrected measurement of usage of the component.