Relays prove valuable when your HID system faces insufficient power from the original headlight harness, as seen in scenarios such as a daytime running light setup operating at 6V, unable to ignite the bulbs. To address this issue, a relay intervenes by delivering full power directly from the battery, activated when triggered by the headlight power connector. Various types of relay connections exist, and it's crucial to choose one that seamlessly matches your vehicle's bulb socket. For instance, an H13 relay features a single H13 connector serving as the trigger point, seamlessly plugging into the H13 headlight connector closest to the battery. This principle applies to other relays like H11 (H8/H9), H7, 9004, 9005 (9006), and 9007. Relays also find application in high-power HID systems such as 75W and 100W HID kits. Connecting these directly to the factory headlight wiring could strain it excessively, making a relay an essential intermediary. Additionally, a relay acts as a safety measure for your headlight system. In the event of issues like a short in a ballast or bulb, the fuse on the positive power lead blows, disconnecting the power supply to the headlights for added safety.

When should you use a relay?

  1. When the vehicle does not supply full 12.6+V DC to the ballasts, such as in the DRL setup.
  2. When the HID ballasts have a hard time igniting the bulbs.
  3. When the HID ballasts ignite a bulb on one side but not the other.
  4. When installing a high power 75W/100W HID system in your vehicle.
  5. When you want to create an fail-safe protection for your vehicle .
  6. When the vehicle's canbus system turns the HID lights OFF after a few minutes of being on.
  7. When the vehicle's light's flash 3x and then turn off. In this case a use of a 50W in-line resistor may also be needed in conjunction with a relay.