LED Headlight Bulb Light Decay: Causes & Fixes

LED headlight bulb has becoming increasingly popular as a brighter, more energy-efficient alternative to traditional halogen lights. But many drivers notice a frustrating problem over time – I obviously bought high power LED car lights, why is the brightness get low over time?

Why does this happen? From poor heat dissipation to poor-quality materials, several factors contribute to LED headlight light decay.

In this blog, we will delve deeper into the causes and effects of LED headlight bulb light decay, exploring various solutions and preventive measures to optimize the performance and longevity of LED car light products.

Understanding the Light Decay of LED Car Light

The so-called light decay is that the brightness of the luminous body is getting lower and lower – this situation is more obvious in HID and halogen lamps.

Normal wear and tear occur as all car parts degrade with use, including headlights. However, light decay is a more specific issue—it’s not just about aging but how much brightness is lost over time.

LED headlight bulbs can not avoid light decay, but its light decay speed is relatively slow, generally difficult to see the change with the naked eye.

However, it does not exclude inferior LED headlight, or inferior light bead board, or due to objective factors such as poor heat dissipation, resulting in faster LED light decay.

Main Cause of LED Headlight Bulb Light Decay

There are many factors that contribute to the light decay of LED headlight bulb, with the most significant factor being heat dissipation. When LED chips operate at temperature exceeding 120 degrees, it expedites the light decay process, causing lamps to deteriorate more quickly.

Other factors that contribute the LED light decay include the quality of LED headlight bulb products, the chip materials, the working environment, and technical parameters.

Also Read: What Makes A Good LED Headlight Bulb, 8 Features to Look For

What Do LED Headlight Bulbs With Light Decay Look Like?

1. LED headlight bulb with coated surface

To show you what do LED headlight bulbs with light decay look like, we tested one of the most common types on the market: LED headlight bulb with coated material on the surface.

While the coating gives them a sleek look, it actually traps heat – causing faster brightness loss over time. Let’s see our test results.

To show you what do LED headlight bulbs with light decay look like, we tested one of the most common types on the market: LED headlight bulb with coated material on the surface.

While the coating gives them a sleek look, it actually traps heat – causing faster brightness loss over time. Let’s see our test results.

Test Result For Coated LED Headlight Bulb:

We began by placing this LED headlight bulb in our testing chamber to measure its initial performance.

At startup, the bulb drew 48.9W of power while producing an impressive 4,056LM of brightness.

However, what truly matters for real-world driving is consistent performance over time. After running the bulb for five minutes, we observed the power consumption stabilized at 32W with light output dropping to 2,811LM.

This represents a concerning light decay rate of over 35%, clearly demonstrating how the bulb’s coated surface compromises performance by restricting heat dissipation and causing significant brightness loss during continuous operation.

2. LED Headlight Bulbs With Ineffective Heat Dissipation

Ineffective heat dissipation is always relative—it only exists when there’s a comparison. When evaluating fan vs. fanless LED headlight bulbs, those with a fan will naturally offer better heat conduction than fanless options.

Similarly, LED headlight bulbs equipped with multiple copper heat pipes and whole aluminum will dissipate heat more efficiently than those relying solely on a copper plate and semi-aluminum alloy.

This time, we’ll use the most common types of LED headlight bulbs on the market to demonstrate what a light-decayed LED bulb looks like—specifically, those with a fan, a copper plate, and semi-aluminum alloy for heat dissipation. Let’s test the degree of its light decay.

Test Result For LED Headlight Bulb With Ineffective Cooling:

We conducted the test just like we did the first time, starting by placing the bulb into our test demo box to measure its initial performance.

Right away, we observed an instant power output of 29W and a luminous flux of approximately 2566 lumens, showcasing its peak brightness.

However, the real test lies in its stability over time. After running for just 5 minutes, the power settled at 27.7W, and the luminous output dropped to 2068 lumens. And compared to the startup power, it can be calculated that the light decay rate is approximately 19%.

Some may consider a 19% light decay rate acceptable, but from a professional manufacturer’s perspective, there’s still room for improvement. Now, let’s take a look at an example of a high-quality LED bulb.

How Do Good LED Headlight With Low Light Decay Look Like?

A good LED headlight bulb isn’t just about high lumens—it also needs to have low light decay for lasting performance.

This time, we’ve chosen the NAOEVO GT6 LED headlight bulb, which perfectly addresses the shortcomings of the two LED bulbs mentioned earlier.

This high-performance bulb features a full 6063 aluminum body and a larger copper tube for superior heat dissipation.

But how does its light decay rate compare with this enhanced cooling system? Let’s find out!

Test Result For NAOEVO GT6

From our test demo box, we observed that the GT6 LED headlight bulb starts with a power rating of 53.4W and an initial luminous flux of 4317LM.

After running for 5 minutes, its stable power remained impressive at 53.2W, with a luminous flux of 4135 lumens. The difference between the startup and stable output is minimal, indicating excellent consistency.

Based on the data, the GT6 LED headlight bulb has a light decay rate of less than 5%—significantly lower than the 35% and 19% seen in above two LED headlight bulbs.

Test Result Comparison

Types of LED Headlights	LED Car Light With Coated Surface	LED Car Light With Ineffective Cooling	NAOEVO GT6 LED
Startup Power	48.9W, 4056LM	29W, 2566LM	53.4W, 4317LM
Stable Power	32W, 2811LM	27.7W, 2068LM	53.2W, 4135LM
Light Decay Rate	≈35%	≈19%	≤5%

The comparison reveals critical performance differences among LED headlight types.

Coated-surface LEDs show significant light decay (≈35%), with brightness dropping from 4056LM to 2811LM due to trapped heat.

Models with ineffective cooling exhibit moderate decay (≈19%), stabilizing at 2068LM from 2566LM.

In contrast, the NAOEVO GT6 LED demonstrates exceptional stability, maintaining 4135LM (≤5% decay) thanks to advanced thermal management.

These results prove that superior heat dissipation—not just high initial output—determines long-term performance.

How To Prevent & Fix LED Headlight Bulb Light Decay?

1. Choose from a trusted brand:

Picking LED headlight bulb from a trusted brand such as Philips, Osram, NAOEVO is crucial.

While many options flood the market, not all deliver the brightness, durability and efficiency they promise. Moreover, such reliable brand provide latest technology in chip, heat dissipation, light beam pattern, ensuring minimal LED light decay.

Learn More: Top 5 Quality Brand For LED Headlight Bulbs

2. Choose LED Car Lights With Proper Heat Management:

From the text we can infer that heat dissipation is the main cause of LED light decay. Therefore, it’s recommend to choose LED headlight bulb with copper tubes, fan and whole 6063 aluminum heat sink.

3. Choose LED headlight bulb With Canbus Driver:

Selecting an LED headlight bulb with a CANbus driver ensures compatibility with your vehicle’s electrical system by stabilizing voltage output, which is particularly beneficial for older cars experiencing voltage fluctuations.

Learn More: LED Car Light Heat Dissipation: Everything You Need to Know.

Why Trust NAOEVO?

Compared to other LED car lights, what truly sets NAOEVO LED headlight bulbs apart is their exceptional stability and long-lasting brightness. Learn more about NAOEVO Story.

Many LED bulbs on the market experience significant light decay, causing them to lose brightness over time.

However, NAOEVO LED headlights are engineered with advanced heat dissipation technology, premium LED chips, and a highly efficient power management system, ensuring they maintain a high and stable lumen output for extended periods.

Instead of quickly dimming after a few months of use, NAOEVO LEDs minimize light decay, meaning they provide consistent and reliable illumination throughout their lifespan.

Whether driving in extreme temperatures or long nighttime journeys, these bulbs deliver strong, clear, and uniform lighting, enhancing both visibility and safety on the road.

Final Words

LED headlight light decay is inevitable but manageable. By understanding the root causes—poor heat dissipation, cheap materials, and electrical issues—you can make smarter choices. Opt for bulbs with copper heat sinks, avoid coated designs, and ensure proper installation. Regular maintenance and voltage checks further extend lifespan. Remember: investing in quality LEDs today prevents costly replacements tomorrow. Drive brighter and safer with these proven fixes.