Having read this paper on LED lighting and using the data supplied in their
own graph on page 3 of their publication it would appear the LED reaches
full brightness at effective time 0s and the filament bulb around 0.3s
(300m/s).
At 30mph my abacus tells me the vehicle will travel some 1.8m (71in). This
is about half a car length Given that a LBC is some 3.6m (140in - ish) long
you would have to be travelling at 60mph for the car length factor to apply.
The voltage loss figures are taken from large goods, commercial vehicles and
double and triple trailers. Hardly from LBCs! (However, if you consider the
lower voltage created by the resistance of aged corroding LBC connectors and
Prince of Darkness designs they could be very valid!)
The paper may ignore the possibility of the following driver being able to
acknowledge the filament brake light illuminating prior to full illumination
although testing has tried to include this aspect.
Whilst there are benefits from LED use they may not as clear cut as the
paper suggests. It may eventually get down to the old argument of
'originality - v - practicality' with a daily driver getting greater benefit
from LED's.
Don't forget they don't have the current draw required for flasher unit
operation if you want to use them for indicators - although there seem to be
ways round this.
Guy R Day
p.s. If I were racing I wouldn't want the guy behind to know when I started
braking and might fit an 'early/late brake light switch' to confuse the
opposition!
-----Original Message-----
Behalf Of Timothy H. Collins
Sent: 05 November 2004 22:08
To: spridgets@Autox.Team.Net
Subject: LED Lights (again)
Back in late October there was a discussion of the benefits of LED lamp
units in LBC's. Here is a link to an interesting paper on a benefit of
using them. Specifically, they light up very quickly which means they can
be seen sooner by the driver behind you (assuming they aren't on the phone,
brushing their teeth, or eating breakfast, etc) The quicker lighting can
mean a car length worth of shorter stopping distance. If you are inclined
to read "scholarly" papers, here is the link: (it is readily
understandable) http://chemistry.beloit.edu/BlueLight/pages/hp/an1155-3.pdf
Tim
ps. It would be interesting to speculate what effect this might have in a
racing situation. Would the lights help or hurt you in a race? Your
"opponent" would know your braking point 200 milliseconds sooner with LED's
than with filament bulbs. Given the number of times you might brake during
a race, there could be an advantage to the guy behind you. Maybe you would
want your friends to use them, but not use them yourself.
(I can already hear it; "I'm always the guy in front" or "I never touch the
brakes in a race.")
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