AC White Paper: Please Don’t Use LED Bulbs in Halogen Reflector Headlights!
LED Bulbs Don't Work Properly in Reflectors Designed for Halogen Bulbs!
I suspect that many of you are familiar with automotive lighting consultant and expert Daniel Stern. Daniel is a good friend and also a consultant to Audette Collection, much to our benefit as he is one of the most knowledgeable experts on automotive lighting in the world. I run everything by him and he has great influence over what is included in our catalog, including veto power.
Daniel simply does not allow LED bulbs to be installed in reflector headlights designed for H4 bubs. If you're interested in why he feels so strongly about this the link will provide you with in-depth information. If that's not enough information here's another informative article. I realize that there are hundreds of LED bulbs designed to replace H4 bulbs out there with tsunamis of glitzy marketing but in Daniel's opinion they cannot be engineered properly to work.
References:
Society of Automotive Engineers (SAE) / Rensselaer Polytechnic Institute (RPI) Study
Citation: Bullough, J., "Investigating the Influence of Headlight Glare and Aim on Risk-Related Driving Behavior,"
SAE Technical Paper 2017-01-1360, 2017
Author(s): John D. Bullough
Affiliated: Rensselaer Polytechnic Institute
Detailed and well researched article by automotive design engineer - January 2019:
https://www.tacomaworld.com/threads/3rd-gen-hid-vs-led-vs-halogen-h11-projector-headlights.589465/
Older well researched article by automotive design engineer - October 2016:
https://www.tacomaworld.com/threads/why-leds-should-not-be-run-in-halogen-reflectors.454371/#post-13377858
More information on general lighting technology
https://www.hella.com/techworld/us/Technical/Automotive-lighting/Headlights-219/
https://www.hella.com/truck/en/trucker/Light-distributions-1553.html
I'll publish more citations here as I come across them. This is not a controversial topic.