April 24, 2019

TT #111 Why Are Motorhome Headlights So Poor? (Part 2)

By: Rob Lowe

Featured Picture

In the previous Technical Tip, I demonstrated the difference between the two headlight configurations available in the USA. Modern cars and trucks use a standard that provides lighting similar to that available since the 1980’s in most of the world. Copies of the older US standard light fixtures are still finding there way into most new motorhomes. With RVer’s purchasing new cars and trucks that have significantly improved light performance, they immediately notice the mediocre performance of their RVs.
Our Path to Improved Headlight Performance:
The following is an example of our route to improved night time vision on our coach. While our coach was under warranty, I had the lights aligned by technicians at the American Coach service facility. That did improve the lighting however low beam lighting was never a strong point of this coach (a 2009 American Coach Allegiance).  

During the early years of our coach ownership, we were still working and taking time off to attend RV Rallies or vacations. We would drive long days to reduce the time away from work. Driving early in the morning and driving later in the evening were part of our schedule. Most of the time, that was not too difficult, since we were travelling on major Interstates and highways or driving on roads through well-lit towns. Our coach is equipped with Daytime Running Lights (DRL’s) which are required for any vehicle registered in Canada. This coach uses the low beam headlight system to comply with the requirements.
One evening after retirement, we were travelling on a late Fall day, on an interstate in Tennessee southwest of Chattanooga. Law enforcement had closed the interstate and every vehicle was forced onto a secondary highway that wound its way along the mountain edge. The road was narrow, unlit and winding, with deep ditches just off the pavement. There was no place to pull off. The headlights were on and even with the fog lights turned on, it was a slow, tension filled trip up and down the dark mountain road. Both my wife and I agreed that the headlight performance really was abysmal.

I decided that it was time to investigate how to improve the low beam performance. When I purchased this coach, I felt reassured since the highlights carried the blue ‘Hella’ logo and looked like a quality lens, reflector and housing assembly with which I was familiar. Since Canada was part of the ‘World’ lighting followers, adopting DRL’s and the European lighting design, I was glad to have a Hella headlighting system that I had a favorable opinion of. Little did I know that the light fixtures in our RV were not the ones with which I was familiar with, even though they shared the ‘Hella’ name.

New European Style Replacements
After seeking sources for information about improving the lighting, it was recommended that I contact Daniel Stern Lighting. While seeking Daniel’s advice, I learned of the divergence between the US and ‘World’ lighting and recollected that one of our suppliers also sold ‘Chevy Silverado’ headlights (copies) to RV makers. These fixtures were foreign produced replicas of the OEM GM parts.  Daniel explained that my coach had inferior replicas and that to improve the lighting, I would need to install European specification headlight assemblies which would be shipped from Europe. I agreed with this recommendation and placed the order. Since I found the high beam performance acceptable (and rarely needed to use them while driving), I decided to refrain from upgrading the high beams. Included with the new assemblies were the recommended bulbs which were manufactured to a high tolerance to better match the fixture, maximizing the light output.

Replacement Low Beam Headlight AssemblyLooking at the light fixtures and comparing them to the similar looking original high beam units, I could see a definite difference in the shine of the reflector with its larger width. The glass appearance was clearer, however that may have been due to new versus old. The left fixture does appear shinier than the adjacent, original high beam units. This is even more discernable in person.
After replacing the assemblies and installing the new bulbs, the improvement was very noticeable. There was more light output, a defined upper light cut-off and the light was whiter. The new bulbs were 55 watts which matched the originals ones. Thankfully, the coach headlight wiring harness and system was high quality and the measured voltage at the bulbs prior to the replacement was more than adequate to achieve full power and maximum light output.
After completing the fixture swap, the challenge was trying to find a truly level surface sixty-five to seventy (65 to 70) feet (20-22m) long to allow the fixtures to be adjust so that the light dropped two inches (5cm) in the 20 feet (6.1m) from the front of the headlights to the target surface, to finalize the adjustment. Parking lots are all sloped for drainage and using a roadway would be a challenge, given the potential for traffic on it especially with a large motorhome blocking visibility ahead. The search for a suitable surface took a few months. This past winter, I was able to use the staging area at our resort where tow vehicles are disconnected upon arrival. It was virtually level and a proper target could be set up to focus the lighting on, then make the adjustments. Adjustment involved getting the proper drop over the distance and ensuring that each light was aimed dead straight ahead. The angle of the light change was correct if the junction of the straight line and the raised portion was directly centered ahead of the center of the headlight.  After about half an hour, the lights were adjusted and performed far better! There was a lot more light on the road, with a whiter color from the bulbs and adjustment was simple since the defined beam of light made it easy to see the changes as adjustments were made. Driving back to our lot was a pleasure, since I could properly see the road ahead.

Daytime Running Light and other Considerations
Our coach uses the low beam headlights as Daytime Running Lights (DRL’s). While it is possible to select another method to meet the requirements, it seemed reasonable to continue to use the new headlights as DRL’s. The more distinct light theoretically would improve the safety during the day.
Had the wiring been insufficient to provide full power, we would have had to provide battery power through a relay to each bulb to ensure maximum power. Daniel can assist with the parts necessary to retrofit such a system, if required. 
As we made our way home from our winter travels, the early morning and evening driving demonstrated the improvement in headlight performance. Even road signs were clearer and when following vehicles ahead of us, we could see the sharp cut-off of the light across the back of them. All this with much better road visibility, clearly defining the road ahead. The upgrade was a definite improvement and well worth the time, expense and effort to complete it.  


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