Whilst those thoughts are thoughtfully thought out ... LEDs used in traditional QH headlights are still too bright, spread incorrectly, non compliant, illegal and give your insurer excuses to excuse themselves from paying out, help the blueys fill their quotas and give the fellow in the wig a jolly good excuse to ensconce you in the brig.
Technically, heat is the main killer of LEDs, and even a modest and commonly accepted manufacturer’s goal of 70℃ reduces their lifespan dramatically. Whereas quartz hal’s happily get all toasty (that’s how they work), H4 headlights are not designed to adequately dissipate the heat produced by a 25 watt LED element. Virtually all of that 25 watts of heat has to try and escape via the narrow alloy billet then out that tiny hole in the back side (?!), which impossibility causes the LED elements to run far too hot, decreasing life and reliability. The dicky little heat sinks and even dickier little fans are not built to cope with the heat, dirt, vibration, oil or Mr Murphy’s daughters.
The 3 expensive sets I bought from a reputable specialist automotive electrical supplier were all poorly designed and (unbeknownst to the supplier’s techs) all had their high beams ‘detuned’ to just a few milliamperes above the low beam input current, to sneak them past Strayan labelling rules.
Be worth having a look to see if Philips made the entire LED assemblies you mentioned, or if they simply made the actual LED elements used in the assemblies. My experience is that Philips don’t make the whole things, but that Philips (and other high quality brand) LEDs are used by lots of manufacturers of lighting devices - some of very high quality and some of shonky, toy or non vital indicator grade (the latter often using the batches of elements downgraded in the testing phases).
Philips interestingly continues to put a good deal of effort into QH globe design and production.
I’m sorry to be a pain in the back side of all our headlights, but LED lights are indeed fundamentally different to all other light sources. They are simply diodes that emit more visible light energy than standard rectifier diodes. Diodes are the earliest and longest developed semiconductor devices, and are extremely robust if treated sensibly. They started out as ‘cats whisker’ detectors in the late 1800s and have evolved via crystal sets, radios and TVs and massive industrial AC and DC power transmission and control systems. They hide inside every vehicle alternator in existence, tolerating engine heat and vibration with pretty impressive durability - try keeping a filament or discharge device going in those circumstances.
Although you’re quite right in saying that white lighting grade LEDs drop around 3.5 volts across their terminals, they are always connected 3 together to form 10.5 volt (or sometimes 4/14volt, 5/17.5volt etc) arrays or elements. This is no different to changing incandescent filament sizes and lengths to suit different voltages, and the whole array is a theoretically and technically true 10.5volt, 21volt or other voltage rated device, not a collection of individual low voltage devices. The arrays are built to match the intended system (ie. 12, 24, 48, 240 or any other voltage), just like a filament globe. Their power supplies then don’t have to drop the supply way down to 3.5volts, but just a few volts or so.
Just like any other past, present and future electronic device, LEDs need appropriate power control systems to ensure they operate as intended. Traditional bulbs require particular gas mixtures, suspension techniques, filament materials, envelope materials (eg quartz glass) sizes and voltages, and sources of suitable power. LED power supplies also conform to the universal rules that the cooler they run, the longer they last, and that ‘you get what you pay for’.
LED power supplies don’t actually have to control the voltage (electrical ‘pressure’), but the current (or ‘volume’ of electricity). They do that by simply switching the power supply on and off at a very high rate (perhaps 30,000 to 1,000,000 times a second), to control the ‘average’ current flowing through the LED array. As these switches are either on or off, they lose very little energy and produce very little heat. The LED supply components are relatively simple and robust (coils, capacitors, heavy duty diodes and transistors, and a simple oscillator device), and operate better and longer the more they are cooled.
The common theme here is that LEDs and their power supplies are highly durable and tolerant of oil, vibration, water, voltage fluctuations, switching and neglect, but they work and last much longer the cooler they are kept. The most important things to consider when casting about for LED spotties then are the build quality, and heatsinking or heat dissipating structures. Look for heavy bodied housings and lots of prominent fins. Separate power supplies are OK, but they introduce potential electrical and connection problems that an inbuilt supply doesn’t.
Hope some of this is useful.



				
				
				
				
					
  Reply With Quote

 there is strong evidence that exposure to powerful sources of these blue wavelengths are doing damage (retinal debris).
				
			
Bookmarks