Run Up of the HID Lamp

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

Each ballast requires higher amperage in order to ensure normal startup and run up of the lamp. Run up is the term used to describe the extra power level given to the bulb (arc tube). The input current during the steady state operation is lower than the start up amperage. After the lamp receives the strike from the starter and the arc is established, the ballast uses its operating voltage in order to provide the run up power needed to keep the lamp on. The lamp rapidly increases in intensity from a dim glow to a very high-intensity, bright light called a steady state. A high watt power level is necessary in order to bring the lamp to a steady state. Within 2 seconds of the arc being established in the bulb, 70 percent of steady state is complete. Within 30 seconds, 100 percent of the steady state is complete.