Tuesday, March 1, 2011

HID lights

I don't know if anyone has been following the storm that's been brewing over HID lamps in recent days. I have been following the storm with interest because it primarily revolves around ignorance ( a pet peeve of mine) and a concern that with ignorance prejudice and bigotry will prevail. And a potential back lash...

This storm started with a piece in The Star on HID lights as retro fitted to cars in Malaysia. As one of many drivers who have been blinded I did agree with that article that something had to be done. But that does not involve banning the HID light.

Let me clarify. Firstly HID lights are in the colour temperature range of sunlight, where the eye works best at. We are equipped to see more and in better detail with greater clarity in sunlight or sunlight like conditions then under yellow light. Yellow light is around primarily through the limitations of technology. When Thomas Edison first invented the incandescent lamp, he had a filament (made of of carbon. The lamp since has seen virtually no change in it's physical structure until the advent of gas discharge lighting (which has NO filament).

Halogen lamps are an 'improved' version of the incandescent lamp in that they still have a filament but the lamp itself is filled with a 'Halogen' gas. This gas results in lamp that runs slightly brighter but still relatively inefficiently. Please see here for tech details Halogen_lamp.

HID lamps like all gas discharge lamps have no filament. In effect an electric arc is generated which ionises the gas within the lamp producing the light. Without getting too technical, in summary gas discharge lamps are far more efficient. How much more efficient? A typical Halogen lamp is rated at 55-60 watts. A HID lamp is typically just 35 watts. It produces as MUCH as or maybe just slightly more light then the halogen lamp for less power. This will directly translate into better fuel consumption, longer lasting alternator and batteries as the entire electrical system of a car is less heavily loaded ( a car's lighting system is it's heaviest electrical load).

So whither the problem? In a nutshell, headlight beam patterns. In countries like the UK there is a mandatory MOT test that cars have to undertake annually. One of the tests they do is a beam pattern test to determine if the light throw is acceptable and NOT hazardous to other road users. You see headlights have carefully designed housings, reflectors and lenses to ensure a beam pattern that throws itself on the road and NOT blind other road users on LOW or DIPPED beams. High beams do not have this control. The designs are so specific that the lamps are actually designed for either left or right hand drive roads/cars (please look here for travel advice under headlights Travel Advice

Any badly adjusted headlight (after an accident) for instance will blind an oncoming driver. The problem with HID kits that are retrofitted is this. THERE IS A DEVICE, IT'S JUST A SHROUD, IN FRONT OF THE BULB/LAMP THAT CONTROLS THE BEAM PATTERN OF THE LAMP ON THE LOW/DIPPED BEAM. The car accessory/mechanics shops here REMOVE THAT SHROUD. Why? Because a lot of drivers who have parted with their cash for these HID kits come back and complain that the lights aren't bright enough. So the shop boys in their infinite wisdom look at this innocuous looking shroud in front of the lamp and think hey it's blocking the bulb so if I remove it..... Then you have the problem as the lights then in effect operate on HIGH beams.

HID lights are good, they are better technology, are 'greener' as they are more efficient and will cause a reduction in accidents as they afford drivers better visibility. They just have to be installed properly and monitored. One solution, have the shops issue a certificate stating that a beam pattern test was undertaken (it's a simple enough procedure http://www.carinsurance.com/Articles/content169.aspx). The drivers carry the cert with them. If a check reveals an improperly installed system, fine the driver and the shop. RM10,000.00 sounds like a nice round deterrent figure :) to keep the shops in line and make them accountable.


Anonymous said...

Very nice article. Long hiatus since the last one :)

I like your scientific explanations.

You should teach part time.


Anonymous said...

Good rant. A long overdued topic for the gov to address!

The other reason for shroud removal is that some HID bulbs, including its adaptor (to convert from H1/H4/H7/HB4 etc), actually extend beyond the original bulb length.

Also, poor beam control is strongly attributed to the wrong location of the source, i.e. the gas arc in the HID bulb is in the wrong position compared to the filament on the original halogen for that same reflector design. Hence wrong point of focus.

How's your new 6ix doing?


Kris said...

Good points from you too M. And simple enough to address with a beam pattern test.

It's doing good but you have me at a loss...