Skip to content
H15 Bulbs Explained

H15 Bulbs Explained

Link to our H15 LED Bulbs.

H15 Bulbs haven't been around as long as some of the other bulbs we supply. Its not uncommon for a headlight bulb to function for two different type of light beams. The once ever so polular H4 Halogen bulb used to functions as the dipped beam and flash, it's no longer used as much in headlights these days and now often found in Vans and some Japanese cars. 

European headlight manufactures started to use seperate bulbs for each function, one of the most common would be H7 for dipped beam and H1 for Main beam.

In 2011 it became a requirement for headlight manufacturers to implement Dedicated Daytime Running Lights, a low wattage light that is automatically activated during the day to aid other road users and pedestrians to be able to the oncoming vehicle more clearly. The DRL should be visible during the day and not used during the night.

Some manufacturers installed what looked like a second sidelight T10 501 w5w to the headlights, a low powered bulb that could be seen during the day and automatically switched off during the night. An alternative to this was to install a twin filament bulb, thats active during the day yet dims down as soon as the Dipped beam lights are activated.

Other manufacturers opted to used the H15 bulb base, a twin filament bulb that was capable of producing a decent amoun of light during the day, but instead of dimming down at night it simply turned off. The second filament is used for the Main beam function. (Flash)

The standard H15 Halogen bulb is displayed below.

Buy Replacement H15 Halogen Bulbs Here

H15 Bulb

This type of bulb using the PGJ23t-1 base is a dual filament bulb, this bulb is capable of producing a Hi / Lo beam pattern as is the H4 bulb.

Many manufacturers have started to use the H15 Bulb to take care mainly of the DRL & Main Beam functions. There are many H15 LED and some H15 Xenon HID Bulb replacements available to buy across the internet. Many people looking to upgrade the H15 are often drawn to the low cost LED versions available, only to find out that once installed they're great for DRL but not so good when it comes to the Main beam function.

Below is a picture of a typical low cost H15 LED bulb.

H15 LED bulbs

The problem is with this kind of H15 LED bulb is that the design has a design flaw, this flaw is mainly down to not being able to disperse heat due to not having any built in heat sink or cooling fan. Because of this the manufacturers are limited as to what LED chips / bulbs can be used. High powered LED chips / bulbs produce quite a lot of heat and they require some kind of cooling. This issue is solved by using either a heat sink and other various heat conductive materials and or a cooling fan to keep the temperatures low allowing the bulbs to run at full power for long periods of time.

Our High Powered H15 LED bulbs produce a super bright white light in both DRL and Main Beam functions. We have tried and tested various types of H15 Bulbs some with heat sinks only and some with heat sinks and fans. We found both types to out perform the low cost LED bulbs shown above, choice of using a heat sink or Cooling fan is normally the personal preference of the customer buying the product at the time.

High Powered H15 LED Bulbs

Link to our H15 LED Bulbs.

Link to our H15 Halogen Bulbs.


Previous article Vauxhall Astra H Xenon HID Conversion Kit
Next article Ford Transit Custom H7 Xenon HID Conversion Kit Canbus Error Free