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AAA: Deteriorated Headlights Produce 80% Less Light

New research from AAA shows that clouded or yellowed headlights generate only 20 percent of the amount of light that new headlights do. According to AAA, most headlights are made of plastic, and exposure to sunlight breaks down the plastic coating, causing discoloration that obscures the amount of light produced. Depending on where and how the vehicle is used, headlights can begin showing signs of deterioration as early as three years to five years, the association reports.

Greg Brannon, AAA’s director of automotive engineering and industry relations, said headlights on U.S. vehicles — even when new — don’t produce a sufficient amount of lighting, “so any reduction in performance is a real safety issue.”

The headlight assemblies used in AAA’s testing were for the driver’s side of the vehicle. According to the association, it contracted an accredited testing laboratory with expertise in automotive headlights and conducted testing according to industry standards.

AAA reports that headlights were tested according to FMVSS-108 standards with no modifications to the headlight assemblies under test or to the test procedures. The headlights were from two popular sedans, approximately 11 years in age. And, results from the degraded headlights were measured against new headlights to quantify the amount of light produced for each.

AAA also examined the effects that replacing or restoring a headlight can have on improving the amount of light produced. Replacing headlights with OE parts was the most effective method to restore light output back to 100 percent, according to the association.

Aftermarket parts also performed well, AAA reports, restoring light output between 83 percent and 90 percent. However, the organization indicates that these did fail to meet certain requirements for light intensity and were found to be more likely to produce glare for oncoming traffic.

Restoring headlights, while the most cost-effective option, offered less of an improvement in light output than replacement, according to AAA. Professional and DIY restoration returned light output back to approximately 70 percent, the association reports; however, both restoration methods produced more glare than is acceptable according DOT criteria.

The professional headlight restoration systems in AAA’s research used a power sanding technique to remove the original protective film from the headlight lens. The resulting scratched surface of the polycarbonate was then polished using increasingly finer grades of sanding discs, and a protectant film was applied to the entire surface of the headlight lens.

AAA’s full methodology is available in the research report found here.

Compounding the problem of driving with deteriorated headlights, AAA contends, is that U.S. headlights have shortcomings. Previous association research indicated that halogen headlights fail to safely illuminate unlit roadways at speeds as low as 40 mph, while high beam settings offer only marginal improvements. According to AAA, even the most advanced headlights tested illuminated just 40 percent of the sight distances that the full light of day provides.

Brannon said: “Driving at night with headlights that produce only 20 percent of the light they did when new, which is already subpar, is a risk drivers shouldn’t take — especially when there are convenient and inexpensive solutions that can dramatically improve lighting performance.”

AAA recommends that drivers check their headlights for changes in appearance, such as yellowing or clouding. And, if the bulb is difficult to see, it’s time to have the lenses replaced or restored, according to the association.

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