LED vs halogen headlights: what’s the difference?

Headlights have been around since the dawn of the automobile, evolving from the early acetylene lamps already in use on horse-drawn carriages, to the adaptive laser units you would find on the latest high-end model.

The most common types of headlights in use today are halogen and LED. Manufacturers are slowly phasing out halogen headlights in favour of LEDs, but both have their benefits and in this article, we will delve into the pros and cons of both types to give you a better idea of which one is best for you.

What is a halogen headlight?

Halogen headlights have been around since the 1960s, they are a modified version of an incandescent light bulb (the ones we all used to have in our homes) and comprise of a tungsten filament enclosed in a glass bulb filled with halogen and a mix of other noble gases. Halogen lights emit a yellowish glow.

What are the pros and cons of a halogen headlight?

Pros:

• Cheap to replace
• Less glaring yellowish light quality

Cons:

• Not that bright
• High power usage

Halogen light bulbs are commonplace in the majority of entry-level cars around the world thanks to their low manufacturing and replacement costs.

Replacing a halogen light bulb is also a lot simpler than swapping out a faulty LED unit, however, you may be doing it more often as halogen bulbs have a shorter lifespan than LEDs. That said, the average cost of a halogen bulb is between £5 to £20, so having to replace them every few years is hardly going to break the bank.

Halogen bulbs aren’t very efficient, though, consuming around 80% more energy than an LED headlight. This can put an extra load on the car’s electrical system and can impact overall efficiency over time.
They also don’t shine as brightly as LEDs, as some of that energy usage gets converted into heat instead of illumination. The dimmer light quality and yellowish glow is less disturbing for other road users, though.

What is an LED headlight?

LED is an acronym for Light Emitting Diode, LED headlights produce light by passing electricity through tiny little semiconductors which emit photons. This electrical process is what illuminates the road ahead. LED headlights emit a very bright white light.

What are the pros and cons of an LED headlight?

Pros:

• Lower power usage
• Very bright beam
• Offers advanced headlight control
• Long lifespan

Cons:

• Can dazzle oncoming traffic
• Expensive to replace

The big benefit of LED headlights is their low power usage relative to the light they emit. They are approximately 80% more efficient than traditional halogen bulbs, this lowers the strain on the car’s electrical system which in turn can improve fuel economy. This is especially important in EVs, where every watt of power saved means more miles between charges.

LEDs are far more versatile than halogens, too, they can be configured in a variety of shapes and sizes, and their hi-tech nature allows for more nuanced adaptive headlight control. Some designs – often referred to as matrix technology – can even switch off individual LEDs to avoid blinding oncoming vehicles.

LED headlights have a far longer projected lifespan than halogens (up to 10 times as long), but when they do give out, they cost far more to replace. A recent study showed that a replacement LED headlight for a Suzuki Swift cost almost £700. A VW Polo’s LED unit was closer to £900.

These costs are partly down to the fact that most manufacturers use sealed headlight units, so you have to replace the entire headlight assembly instead of just the LED unit.

On a budget car that is 15-years old, a blown set of LED headlights may write-off the entire vehicle. However, prices always come down as new technology becomes more commonplace. And with most manufacturers already shifting over to LED headlights – over 60% of all new cars globally have LED lights as standard – this should be the case here as well.

Can you replace halogen bulbs with LED bulbs?

Not legally in the UK. There are many aftermarket suppliers offering LED headlight replacement kits for cars with halogen lights (a kit is required as power and cooling differences between the bulb types mean you can’t just swap bulbs), but unfortunately it is not legal to make this upgrade due to legislation that does not provide a certification process for aftermarket LED headlights. Some consider this unfair and have campaigned for the legislation to be updated, but all we can do is advise you of what the rules are.

The MoT testing manual was also updated in 2021, telling testers: “Existing halogen headlamp units should not be converted to be used with high intensity discharge (HID) or light emitting diode (LED) bulbs. If such a conversion has been done, you must fail the headlamp [the car will fail its MoT as a result].”

Which is the better headlight – halogen or LED?

With auto manufacturers already well on the way to adopting LED headlights as standard fitment, the days of the halogen bulb are numbered.

If you are buying new, the choice is often already made for you, although upgrading to adaptive LED headlights or even laser lights is sometimes an option on luxury models. The stronger light quality, long lifespan and lower energy use of LED lights make them a great choice in general, and replacement costs should come down as market adoption rates increase.

Halogen lights still have their place in budget cars, as well as in the used car market. The low replacement costs are the biggest drawcard, ensuring that a blown bulb or damaged headlight unit don’t equate to an exorbitant replacement cost.

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