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| Headlight Questions https://slantsix.org/forum/viewtopic.php?t=19996 |
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| Author: | emsvitil [ Tue Oct 03, 2006 1:12 pm ] |
| Post subject: | Headlight Questions |
A few headlight questions: 1. What's the voltage that headlights are rated at (I think it's 12.  2. Is there a chart somewhere that shows expected lifetime vs voltage (more voltage, how much shorter life; less voltage, how much longer life) 3. Similiar chart for light output vs voltage 4. A reasonable upper limit on voltage input to a headlight for max light output (assuming that you isolate the headlights from the rest of the electrical system) |
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| Author: | sandy in BC [ Tue Oct 03, 2006 1:32 pm ] |
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Uhhhh.....I think Dan just left for Europe. |
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| Author: | slantvaliant [ Tue Oct 03, 2006 2:48 pm ] |
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Dig around here until Dan gets back (He won't mind): http://www.danielsternlighting.com/tech/tech.html More than you ever wanted to know about automotive lighting. |
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| Author: | SlantSixDan [ Thu Oct 05, 2006 6:15 pm ] |
| Post subject: | Re: Headlight Questions |
Quote: A few headlight questions:
Well, here I am. I just got home from eleven hours in the air back from France, where I was at a headlamp R&D congress (really cool nighttime test drives...LED headlamps are just around the corner, and I got to drive a brand-new €60,000 Citroën C6 with swivelling/autolevelling Xenon projector beams!)...so it will be nice to think about nice, simple glowing-filament ones that stay put for a change.Quote: 1. What's the voltage that headlights are rated at (I think it's 12.
US automotive lighting devices are all rated at 12.8v, yes.Quote: 2. Is there a chart somewhere that shows expected lifetime vs voltage (more voltage, how much shorter life; less voltage, how much longer life)
Output-Fn = Fr (V'/V)^3.3 Life- Ln = Lr (V'/V)^-13 where: Fn = new output Fr = rated output Ln = new life Lr = rated life V' = new voltage V = rated voltage If you don't have Fr or Lr values, you can knock those variables out of the equation and just get a multiplier. Quote: 4. A reasonable upper limit on voltage input to a headlight for max light output (assuming that you isolate the headlights from the rest of the electrical system)
Depends on the type of headlamps you're running, which is a significant question because while you can make any filament lamp brighter or dimmer by varying voltage, this does not have an effect on the quality or focus of the beam itself. What is your specific goal? You wanna see better, you wanna wring the highest possible intensity out of a particular pair of headlamp beam units, something else? One of the nice things about owning an old car is that the standard-format headlamp buckets mean you have a fairly wide choice of beam units you can install... |
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| Author: | emsvitil [ Thu Oct 05, 2006 6:54 pm ] |
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Equations, great.. This came from an expansion of the MOSFET idea..... Why not run a boost converter to the lights for more light. (or at least constant output so there's no voltage loss no matter what the rest of the system is doing) I think upper limit is where the equations breakdown and the lights go 'poof' when you hit a bump. I was thinking the 15-16v range. (or even adjustable) |
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| Author: | SlantSixDan [ Thu Oct 05, 2006 7:29 pm ] |
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Quote: This came from an expansion of the MOSFET idea..... Why not run a boost converter to the lights for more light.
Been done—do a search for "Catz Zeta". Really poor idea. You get headlamp life measured in tens of hours. If better seeing is the goal, it's better to run more powerful bulbs fed losslessly at something somewhere near rated voltage.Quote: I was thinking the 15-16v range.
Let's run some numbers:Output % of rated flux, Life x rated hours 10.5V : 51.0%, 13x 11.0V : 59.7%, 7x 11.5V : 69.5%, 4x 12.0V : 80.3%, 2x 12.5V : 92.3% 1.3x 12.8V : 100%, 1x 13.0V : 105.4%, 0.8x 13.5V : 119.8%, 0.5x 14.0V : 135.6%, 0.3x 14.5V : 152.8%, 0.2x 15.0V : 171.5%, 0.1x 16.0V : 213.5%, 0.06x |
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| Author: | emsvitil [ Thu Oct 05, 2006 7:49 pm ] |
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I thought the rated life was at 14volts........... So you're better off doing the following: 1. Upgrading your wiring first. then if that's not enough 2. Better bulbs. (why waste good bulbs on crappy wiring  )Thanks, I'll just work on the MOSFET relay idea with better wiring then..... |
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| Author: | emsvitil [ Thu Oct 05, 2006 7:54 pm ] |
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It shouldn't matter what side the relays are on if you protect the circuit with a fuse right?????? I was thinking alternator to right side light, run 3 wires to left side light (power and 2 grounds from right side light) then run the 2 ground wires to relays and from relays to battery ground. The idea being that the lights get the higher output of the alternator before any other circuits, and both lights would have the same amount of total wire length so they would be identical brightness |
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| Author: | SlantSixDan [ Thu Oct 05, 2006 7:55 pm ] |
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Quote: I thought the rated life was at 14volts
Some small bulbs (signals and indicators) are life-rated at 14v. And, weirdly enough, dual-filament US-spec bulbs (e.g. the 1157) are output- and life-rated at 12.8 on the major filament, 14.0 on the minor!Quote: So you're better off doing the following:
Good idea.1. Upgrading your wiring first. Quote: 2. Better bulbs. (why waste good bulbs on crappy wiring
Or look at it from the other end: Seems a shame to run good wiring to cruddy headlamps!
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