The
color of a light source is expressed as a 'colour temperature'. As
the color temperature increases, the color of the light moves from
yellow to white to blue to purple. The suns white light at noon is
5500K. HID light his a higher color temperature than standard halogen
headlights, which gives it a crisp white appearance.
Factory
fitted gas discharge globes have a colour temperature of around 4200K,
these seen on the low beams of most new European cars. HID kits and
replacement globes for factory HID are available in colours ranging
from 4200K to 12000K. Interestingly, an HID bulbs colour temperature
will increase slightly over it's lifetime producing bluer and bluer
light the longer it is used. A 'burned in' bulb which began at 4200K
will after say 500 hours produce light at 5000K.
It is
a common misconception that color temperature relates to the heat
output of a bulb or measures the brightness of it's light.
Lumens
(lm) are the international unit of luminous flux or quantity of light.
The following show a test between two motorcycles high beam lighting.
One bike is fitted with a standard halogen bulb on high the other
an HID high.
The considerable
difference is largely due to the number of lumens produced by each
bulb. A candle produces about 12 lumens and a household 60W incandescent
bulb around 830. A standard 55W H1 halogen produces around 1550lm,
with a similar 'Xenon blue' halogen bulb's producing fewer lumens,
due to those that are cut out by the filter which only allows the
blue light to escape. A blue 55W halogen H1 may produce 1400lm.
| Halogen
Bulb |
Watts
(W) |
Lumens (lm) |
| H1 |
55 |
1550 |
| H2 |
55 |
1800 |
| H3 |
55 |
1450 |
| H4
(9003 High/Low) |
60/55 |
1650/1000 |
| H7
(13.2V) |
55 |
1500 |
| H8
(12.8V) |
35 |
700 |
| H9
(12.8V) |
65 |
1870 |
| H11
(12.8V) |
55 |
1200 |
| HB1
(9004 High/Low) |
65/45 |
1200/700 |
| HB4
(9006) |
55 |
1100 |
| HB3
(9005) |
65 |
1900 |
| HB5
(9007 High/Low) |
65/55 |
1350/1000 |
Bosch/SAE Automotive Handbook (4th Ed.)
Lumen
output varies somewhat between HID bulbs too. Colour temperatures
4200-6000K produce the most light,
with higher colour temperatures producing marginally less. However,
even the highest temperature colored HID bulbs produce a far greater
quantity of light than any halogen bulb.
| HID
Bulb |
Watts
(W) |
Lumens (lm) |
| 4200K
|
35 |
3200lm |
| 5000K |
35 |
3200lm |
| 6000K
|
35 |
3000lm |
| 8000K
|
35 |
2700lm |
| 10000K |
35 |
2600lm |
| 12000K |
35 |
2500lm |
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