Why do Halcyon HID lights have the extra ballast unit on the handle?
Explorer 9/18WThe ballast in an HID lighting system generally has two purposes. It provides the proper starting voltage to strike and maintain the arc, and it regulates the proper current to the lamp once the arc is established. Ballasts are not interchangeable among different types of HID lamps. A ballast design incorporates electronic circuitry to provide specific lamp/ballast operating characteristics. As an example, the effects of line voltage variations on resultant changes of lamp wattage are a function of the ballast circuit design. Requirements for a circuit which will provide a finer degree of lamp regulation generally result in a higher ballast cost.
