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cjiom said:
01-20-2004 09:25 PM
I bought some silver star bulbs to try, but they ended up in my car : - (Must get some more next time I am in the factor and try on the bike).
One thing my factor did say was that they were not sure of the use of these in plastic headlights and that that would be at my own risk. Nearly all osram bulbs (thats how they are branded here but think they are the same) are low UV and safe with plastic lenses. The EX seems to have a class lens anyway.
I have only had one headlamp fail on me and that was after 27000 miles so I presume that (unless it was replaced) they last quite well.
High output lights should have a slightly lower life than the "long life" bulbs, but then you get more light so can see where you are going better. The super bright H4 is the same technology used in the H7 I believe and they are fitted as standard by many auto manufacturers. If there was a problem they would not fit them. Thats how I feel anyway.
There is life span data at www.osram.com
Technical - Life
B3 @ test voltage 13,2 V 150 / 150 h
Tc @ test voltage 13.2 V 350 / 220 h
Does anyone know how to interpret this?
I am new in this forum, this is my first post. I found the forum while searching Google to find exactly the same answer: How to interpret this!

Well, I found the answer inside the same osram webite. Here I quote:

What do B3 and Tc mean in connection with the service life of lamps?
If we consider the service lives of products that are designed to last a certain time we can see that they all have the same or similar failure characteristics.
If we plot the service lives of the individual lamps on special logarithmic graph paper, the graph produced is called a "Weibull distribution curve".
In a stable production process we obtain a straight line for the service life on which we can read off various life values. For its products in the automotive sector OSRAM specifies a B3 value, which indicates the time at which 3% of the tested lamps have failed. OSRAM also specifies the Tc value (characteristic Weibull value), which indicates the time at which 63.2% of the lamps have failed.
It used to be the case that only the average value was specified (the average life), which in this system would correspond to a B50 value (i.e. the time at which 50% of the lamps have failed). By specifying both the B3 value and the Tc value it is possible to get an idea of the spread of the product's service life and hence the quality of the product.
In America B10 is also given. This value can be calculated from the B3 and Tc values."

You can read this above text (and more info) here:

However, I still have a question (to which the faq section does not reply):
All times are give as:

Technical - Life
B3 @ test voltage 13,2 V 250 / 400 h
B3 @ test voltage 13,5 V 180 / 290 h
B3 @ test voltage 14,0 V 110 / 175 h
B50 @ test voltage 13,2 V 470 / 840 h
B50 @ test voltage 13,5 V 340 / 600 h
B50 @ test voltage 14,0 V 205 / 370 h
Tc @ test voltage 13.2 V 500 / 900 h
Tc @ test voltage 13.5 V 365 / 650 h
Tc @ test voltage 14.0 V 220 / 400 h

What is the meaning of 250/400, 180/290, etc? In some lamps the stroke separates different values (as above), in some the values on either side of the stroke are the same.
Does anyone know why this?
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