Extra bright lights and wattage (was Hella vs others)

["John Fielding" <johnf@domain.elided>]

I noticed a thread a week or so back about fitting after market headlight
units to some of the earlier model Alfa cars.  In my browsing on the net I
came across an interesting document about HID headlight units now being
fitted to top-end models by various manufacturers.  These use a type of high
voltage discharge lamp which gives a surprisingly high light output compared
to conventional tungsten filament lamps.

One application note I found by Siemens detailed the design of  the
necessary high voltage generator (which is built into the lamp unit) and
develops about 350V DC from the 12V vehicle electrics.  The total power
consumption is about 34W and the light output is equivalent that given by a
normal 130W lamp!!  You may have noticed these HID (High Intensity
Discharge) lamps on some Volvo, BMW and other luxury cars, they have a
distinct greenish/blue colour to them and are very bright. One manufacturer
is Tungsram, no doubt there are many more who offer these now.  With these
HID lamps there would be no need for relays as the current drawn by each
lamp is only about 3A..

The claimed life of these lamps is well in excess of that given by a
tungsten filament lamp and they do not suffer from blackening of the lamp
glass with age.  However the introduction of these HID lamps was somewhat
delayed before the major manufacturers of these lamps could meet the
mandatory "light-up time" of less than 1/2 second.  Early version took as
long as 5 seconds before the light output was satisfactory, no good for
those who engage in "flashing"!

Just thought you might like to know.

John Fielding
Durban
South Africa

Alfetta 1.8L turbo

--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided