Lifetime Decrease of Halogen Lamps for Automotive by Duty Cycle Stress

We analyze the effect of input voltage and interruption processes that frequently occur while driving, and how they decrease the lifetimes of halogen lamps used in automotive headlights. First, we established estimated lifetimes of halogen lamps regarding short-term use, taking accelerator use into consideration. Through failure analysis, we discovered that the main cause of failure in open halogen lamps were the single wire filaments. We estimated lifetimes, factoring in acceleration in both continuous running and on and off conditions to examine life shortening due to the interruptions. The result of comparing lifetimes of continuously running lamps and on-off lamps found that lamps that were turned off and on had roughly a 31% decrease in life span. This shows that the inrush current generated when turning on a lamp is the main stress shortens the lifetime of lamp. Therefore, automobile manufacturers should provide information about lamp replacement cycles to customers or they should determine lifetimes by conducting additional on-off tests rather than simple continuous tests to find products with longer replacement cycles.