I guess is the normal ballast is a magnetic base that builds to control the electrical current that flows through the HID lamp. If electrical current was to flow into the light bulb at full voltage, the bulb would burst, so the controlling factor offered by the ballast is necessary for the correct function of any HID light. A magnetic ballast consists of one or more aluminum or copper coils that sit on a core that is made up of steel laminations. The coils and core work in conjunction with a capacitor, and sometimes an igniter. These four parts are most often built into the ballast casing.
A Digital ballast offers the same electricity control as does the magnetic ballast, but with the digital model the current conforms to optimal levels of performance for each specific type and wattage of lamp, possible through digital circuitry. Because of the more consistent application of electrical current, the lamps last longer and function at a higher level using less power with a digital ballast.
With a digital ballast, the light produced is more consistent. Magnetic ballasts, especially as they age, become more noisy when they operate, cause the HID lamps to flicker and also contribute to irregularities in the color that the lamp gives off. The digital units can also sense when the lamp is almost used up, and can shut the unit off when it is not functioning optimally.
Canbus ballast – because of HIDs operate on 35W whereas halogens operate on 55W. In some advance vehicles such as BMW, Audi, Benz, the difference in current will trigger a "low beam failure indicator" or a "fast blinking error." As a result, your HID Conversion kit will not function properly. Canbus ballast will solve this type of error.
