Bulb output degradation

On Thu, 24 Mar 2005, David Cole wrote:

> The car is an 02 VW golf, I think it was an Sylvania/Osram 64210L H7 and
> that's what I put in.

OK, that's a long-life/less-light bulb.

> The difference from one side to the other was obvious when parked in
> front of a wall. I think the DRL on my car goes full intensity low
> beam.

Actually, the VW DRLs are reduced-intensity low beam. The intensity
reduction isn't very obvious to the naked eye, especially in the daytime,
because low beam DRLs have to be run at at least 76 percent of normal
voltage. But it's enough to increase and accelerate the light degradation
with age.

Not only to long-life bulbs produce less light when new (as a result of
the internal changes made to maximize life) but they live long enough to
grow very dim.

DS



> "Daniel J. Stern" > wrote in message
> .umich.edu...
> > On Wed, 23 Mar 2005, David Cole wrote:
> >
> >> Another bulb related question.... What is the degradation in light
> >> output as a bulb ages? I put a new H7 in my car and I can see the
> >> difference from one side to the other.
> >
> > Assuming a first-line bulb (not a cruddy Asian-made one), and assuming no
> > reduced-voltage daytime running operation, lumen maintenance is around
> > 90%. Reduced-voltage daytime running operation causes bulb output to drop
> > much further even when the bulb is operated at full voltage.
> >
> > The bigger difference is in the *type* of bulb. Ultra-high-efficacy bulbs
> > produce more light than high-efficacy bulbs produce more light than
> > standard bulbs produce more light than long-life bulbs produce more light
> > than blue bulbs.
> >
> > What kind of H7 did you take out of which headlamp in what kind of car?
> > What kind did you put in?
> >
> > DS
>
>
>