In traditional halogen H4 bulbs the low beam filament (the one with the reflector/shield) point in a 180 degree field and the high beam has no shield and has a full 360 degree coverage. This is how all H4 light assemblies are designed to use.
Why then are there no H4 LED bulbs which use this layout? They all have terrible design or are only designed for low beams.
Actually that's not being fair, Phillips have a product that does this, but they are quite pricey. 400AUD pricey.
I think you hit it. Cost, most of the LED headlights are made to just pack as many LED as possible into the H4 package as possible, but a small percentage of them are actually designed to mimic the H4 fillament. Most of the cheap LED bulbs aren't DOT certified, so look for the certified ones, they give you better performance. I'd recommend a brand, but you're already aware of the Phillips.
The biggest issue with high-intensity LED's is heat dissipation. Heat is an LED's #1 enemy, regardless of the LED package.
High-powered LED's that put out about 2 to 5 watts of light each (9 times more than the power they consume) need be be epoxied to an aluminum or copper heat sink, maybe even fan cooled.
But I see many LED street-lights with LED's burned out, probably due to a poor heat-sink procedures. They did not even last the 5 years expected of them.
High intensity lights for cars have the problem of no space to dissipate the heat. I do not think they will compete with quartz-halogen lights until the reflector itself is an array of LED's epoxied to a metal plate. LED's for brake and turn signals will become more common as they can be mounted flat on a metal plate to absorb the heat.
They have already done this with some high-intensity flashlights, getting the basic engineering right first. LED's can last for 20 to 200 years continuously, if you can keep them cool and not run them at full power.
( Based on 100,000 hour MTBF at nominal drive current and temp ambient of 25deg Celsius )
