April 23, 2019

TT #110 Why are Motorhome Headlights so Poor? (Part 1)

By: Rob Lowe

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I often hear this question when I present seminars about L.E.D. bulb replacements on RVs. Frequently RVers mentioned that their new coaches have headlights worse than their older ones. As it turns out there is a logical explanation for this. It is only recently that headlight performance has improved. We are accustomed to new cars and trucks having excellent, defined headlight beams and we naturally expect our new RV to have a headlight system that performs in a similar fashion.
FACT: RV Headlights are Copies of Older Vehicle Headlight Assemblies
NOTE: I have used some photos and information from a headlight consultant’s website. It is www.danielsternlighting.com Daniel has an excellent overview of lighting on his website and his headlight expertise is excellent. Refer to his website, if you want more information and detail on this topic. (In full disclosure, I purchased replacement headlights for my current coach though this firm and his recommendations corrected the issue. I will explain more about this later in this article series).

RV makers rarely make their own headlight systems. If they did, they would have to go through all the testing and demonstrate that they meet the Federal Motor Vehicle Safety Standards and the DOT Specifications. This would greatly increase the cost per RV. As a result, they typically specify a headlight assembly from a car or truck that may be fifteen (15) to twenty (20) years old. They craft their front caps to fit that headlight system into the new cap. Of course, that cap will be utilized in RV production for a number of model years. As a result, the headlight in your RV was designed to meet the requirements in effect twenty (20+) or more years ago. Combine this reality with the fact that the copy likely does not meet the stringent Original Equipment Maker’s (OEM’s) specifications and their high quality standards for the materials used, the finish on chrome or glass parts and so on. This is crucial to understand as we move forward through this TechTip.

Euro Headlight pattern
There are two major factors that impact the quality of the headlights and their performance. The first is that the US diverged from the criteria and design specifications that were adopted by the majority of other jurisdictions in the world during the 1980’s (World’ Spec’s). That was around the time that the auto industry moved from sealed beams and adopted daytime running lights (DRL). With a bulb installed in a separate reflector the lighting engineers could better focus the light and the standards in Europe were more mature and often adopted by new countries with booming automotive production facilities (Japan, Korea, among others). The bulb designs often started with the letter ‘H’ followed by a number such as H1, H4 and so on. The bulbs were manufactured with a new (at the time) process that included a halogen gas to create a whiter light than a standard incandescent light. Each bulb had the filament optimally placed to give more light where needed when inserted into an appropriate fixture. The approach used in European (‘World Spec’) jurisdictions was to have a sharp light cut off at the center of the headlight and increase the angle on the right (curb) side so light was focused on the road ahead and along the shoulder of the road. The photos in this Technical Tip from www.danielsternlighting.com clearly contrast the two approaches. 

US regulators wanted more light down the road in a broad "down the road view” with some additional light on the right side.  Contrast the light output diagrams which clearly show the difference.

US Headlight Pattern
As you can see from these pictures, there is a great divergence in the lighting pattern, with the US taking the ‘blob of light’ approach broadly scattered down the road.
The other factor that Daniel pointed out in his articles is that the headlight systems used in larger Type ‘A’ motorhomes are copies of the original equipment maker’s (OEM’s) ones. With a lower price for the RV makers, comes a lower quality reflector, lens and potentially less precise bulb placement. Combine that with a wider vehicle than the one which the original assembly was designed to fit and light performance is degraded. The copies of OEM’s headlight assemblies are duplicating the lighting used when the US standards were at odds with the world consensus. That is the ‘new’ assemblies are copies of the ones used before the US came into agreement with the other ‘World’ standards. The US Regulators developed their own standards that often mimicked the European specifications and the now current US bulbs are typically numbered as 9003 or 9007 and so on. All of these factors contribute to less than optimal performance in a RV setting.
Before going to any drastic measures to improve the lighting performance on a motorhome, have the lights properly aimed. The information to do this is found at this weblink: http://www.danielsternlighting.com/tech/aim/aim.html In the next TechTip, I will detail the changes I made with our coach and give some feedback on the performance improvement.


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