Even if your car’s headlights aren’t adaptive, they’re still an important car safety feature. After all, if you can’t see the oncoming danger, how can you avoid it? That’s why, to try and counter poor headlight performance, many turn to LED bulbs to brighten up the road. And since LED headlights aren’t always standard, that often means trying to fit the bulbs in halogen housings. But trying to upgrade your lights that way isn’t always worth the hassle or expense.

LED headlight bulbs aren’t drop-in halogen replacements

It’s important to note that LED headlights are distinct from halogen ones. And while some advertise the former as ‘LED bulbs,’ that’s actually incorrect terminology.

Halogen headlights work like traditional incandescent bulbs. Inside the bulb is a tungsten filament (the ‘heating element’) surrounded by halogen gas. As current flows through the element, it starts to glow, releasing light and heat. Xenon bulbs, aka ‘high-intensity discharge’ bulbs, lack the filament; instead, they use electrical current to directly heat xenon gas.

LED headlights, though, don’t work the same as either of these two. They work by passing electricity through semiconductors, which release light, Cars.com explains. They use no gas and contain no filaments.

LEDs have a few advantages over halogens. They’re brighter but consume less power, don’t heat up as much, and take up less space. However, you can’t simply replace a halogen bulb with an LED assembly. While there are conversion kits available, they have a few drawbacks.

Firstly, although the LEDs themselves run cooler than halogens headlights, they heat up everything around them. As a result, not only do they need separate current regulators, they need dedicated cooling accommodations. So, while the individual LEDs may be smaller, the entire headlight conversion kit may take up more space overall.

Secondly, converting halogen headlights into LED ones might not actually improve visibility. And that has to do, not just with the lights themselves, but with what’s around them.

The problem with headlight reflectors

All automotive headlights need ways to focus the light their bulbs/LED assemblies produce. It’s especially vital for LEDs, because, unlike halogen bulbs, their light isn’t omnidirectional. Without something to bend or reflect their light, they’d still be brighter than halogens, but only in one direction.

And that’s the biggest problem with converting halogen lights to LED ones. Modern car headlights typically use either projectors or reflectors. Both use mirrors to reflect light, with the latter using a lens to further focus it.

However, unless the headlight assembly is shaped with the ‘bulb’ technology in mind, it won’t distribute light properly. The space right in front of your car might be a bit brighter, but further out, it may actually be darker.

Plus, even though LEDs are brighter, they don’t always improve visibility. Sometimes, halogen headlights are actually the better choice. Because LEDs are so bright, OEMs sometimes have to ‘tone down’ the reflective mirrors. Otherwise, they’d broadcast a solid wall of light.

In addition, LEDs produce more glare at short distances. In front of a wall, it looks like they’re giving off more light than halogens. But that’s not necessarily what you want in, say, a snowstorm.

Finally, even if LED headlights throw more short-distance light, they don’t always do the same at longer distances. That’s the difference between lumens and lux. The former is about output, the latter about illumination. Just because an LED puts out more lumens, doesn’t mean it’ll put out more lux.  

How can you upgrade your car’s headlights?

If you absolutely want to upgrade your existing halogen headlights into LED ones, there is a proper way to do so. That’s by removing the existing reflectors and replacing them with new, LED-compatible projectors.

However, while proper projector conversion kits are available, they’re not necessarily available for every vehicle. In addition, the conversion process requires not just removing the old reflectors, but also installing new wiring, mounting new hardware, and sealing the new projectors in. Plus, the kits aren’t that cheap; depending on the car, they often run $200-$600 or more.

But while LEDs aren’t always the best halogen replacement, there is another headlight that does benefit from an LED upgrade: a sealed beam. Sealed beam headlights are similar to halogen ones in that they use filaments. However, when the bulb burns out, the whole assembly gets replaced.

Hence the ‘sealed’ in ‘sealed beam’: it’s one sealed unit. Because of this construction, sealed beam LED conversions don’t run into the reflector/projector issues. The new housing is designed to work with the bulb from the start.

However, even if you have halogen lights, you may not need to upgrade. If you’ve noticed your headlight lenses look foggy or cloudy, it’s possible to restore them. In addition, the bulbs may be improperly aligned. Luckily, the readjustment process requires little more than a tape measure, some tape, and a screwdriver.