Upgrading Dual Filament Bulbs

Updated: June 2018

If your car use one bulb to give both high and low beam, that means your current bulb has two filaments, a dual filament bulb is nothing but a halogen bulb with two lighting filaments side by side.

In order to convert this type of halogen bulb to HID (or LED), you must first understand Dual Filament Halogen Bulbs. If your vehicle uses the following bulbs then this post applies to you.

– H4 (Also known as 9003, HB2)
– 9007 (Also known as 9004)
– H13 (Also known as 9008)

We have 2 HID options to choose from if your vehicle uses one of the bulb types above as well as an LED option:

Option 1: Hi/Lo kit

A Hi/Lo kit converts the low beam to HID while high beam stays as halogen. This bulb is the one most used since most drivers usually are okay with only upgrading the low beam and it's also the least expensive. This bulb adds a halogen bulb off center of the HID low beam bulb in order to satisfy the high beam requirement. (whatever reason that may be). From our website, they will be labeled H4-2, H13-2, or 9007-2 (The -2 indicates it only has 2 bulbs side by side.. the HID low beam bulb and the halogen high beam.

Option 2: Bi-Xenon

A Bi-Xenon kit converts both low beam and high beam to HID with one single bulb that shifts upward when is switched to high beam. It uses an electromagnet to change the physical position of the HID bulb for the low beam as well as high beam. This moving bulb adjusts the focal length and adjusts light output to a wide angle for high beam, and a tighter more focused light for low beam. From our website, they will be labeled H4-3, H13-3, or 9007-3 (The -3 indicates it is a bi-xenon bulb).


Option 3: LED bulbs

This is personally our favorite option when it comes to dual filament bulbs because these LED kits upgrade the high beam at no additional cost. There is also no additional wiring involved to do this where-as in the Bi-Xenon HID kit mentioned in option 2, you have to wire a relay, and while there isn't anything wrong with that.. installation seems to be daunting to most people looking for a simple installation. We have a couple LED options to choose from, they can be found on our LED products page.

A caveat to installing HID and LED bulbs to replace dual filament bulbs:

While standard halogen bulbs do not require specific polarity (meaning the power and ground side of the bulb do not matter), it does matter for HID's and LED's. In the case where the light will not turn on, the plug can be flipped in a 180 degree. This can be a problem with dual filament bulbs since they can only be installed one way, and because HID's and LED's are designed with the most common polarity configurations. Because polarity does not matter for halogen bulbs, some manufacturers are inconsistent with standard polarity configuration in the connectors. In this unfortunate situation, it is important not to blame the HID or LED kit, and realize that the wires in the connector on the HID plug (or vehicle power plug) need to be switched from one side to the other. Note that manufacturer errors such as this are rare, but they do happen.

Summing it all up:

If you need or want both your low beam and high beam to be upgraded then you should buy a Bi-Xenon HID kit or one of our LED kits we offer, as these upgrade both high and low. While as if you purchase the Hi/Lo HID kit, only the low beam will be upgraded while the high beam will remain halogen.