Browse Publications Technical Papers 2005-01-1450
2005-04-11

On-Car Evaluation-Methods to Understand Condensation in Headlamps 2005-01-1450

On today's cars, headlamps have become one of the predominant styling and design features that affect consumer satisfaction. With clear-lens headlamps becoming more complex, a critical challenge is to minimize or eliminate condensation inside the headlamp. This is difficult to accomplish without a method for understanding, testing, and measuring the moisture that causes condensation. Current lab tests, such as FMVSS-571.108 S8.7 and others, fail to predict actual field performance due to the effects of critical on-road variables, such as wind, sun, rain, engine heat, and so forth.
On-car testing analyzes conditions inside and outside the headlamp during actual operation of a vehicle in various driving situations. Critical testing variables include internal headlamp dew points on both the left-hand (driver) and right-hand (passenger) side, external dew point, and vehicle driving details, such as test date, driver, start/stop time, type of drive, weather conditions, status of the headlamps, and visual confirmation of condensation.
This paper reviews methods for testing causes of condensation in an on-road environment. It then describes the superior results of using an on-road vehicle as a test platform, rather than laboratory tests, to confirm the performance of various headlamp designs and condensation management venting systems. Finally, it shows how on-road testing can also be used not only to evaluate current field problems rapidly and redesign headlamps to correct the problems, but also during the initial design process to prevent potential field problems from occurring.

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