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Light project part 1

Old 11-08-12, 05:43 PM
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Exclamation Light project part 1

Promised some details about the personal lighting arrangements I've been working on a while back so here's a start. Due to photo posting restrictions I'll be doing this in three separate sections. Part one will cover a headlight mount and light descriptions, parts two and three will have beam shots of multiple light arrays.

Over the past year and a half, I've been touching bases with people at three different companies marketing versions of some industrial lights coming out of Korea. None of this is some radical new design - the stuff I'm going to show you is already 5 years old. They have newer more high tech products on the market - for reason of my own I stuck with this particular P7 version.

Please note there's no reflector in this unit. Just a collector / focusing lens. Collimators like this can approach 93% optical efficiency vs a reflector which is about 60%. Most single emitter bike lights and flashlights use a smooth or orange peel or fluted reflector. Lenses are more efficient and much more common on higher end lights that use multiple emitters. This particular version also comes with diffusion inserts that will change the spread from 10 degrees to 15 degrees or 35 degrees. Later models incorperated the diffusers into the lens for greater optical efficiency. I'm willing to accept a 2% drop in efficiency for the chance to experiment.

The unit is cast and is self contained - the light engine is incorporated in the unit. It will run off a range of DC voltages; anything from 9V to 50V. When the voltage drops below 9V the lamp simply shuts down. There are no warning lights, no dimming controls - just a power input. Its possible to connect this to external controls, but different power levels are to save the battery - and many people run their lights on full regardless. I'm not one for bells and whistles and this was a 'plus' to me since I plan to run with the lights on all the time anyway.

So whats the output like? These use a P7 emitter and aren't run at full potential. Specs say 80% of the 900 lumen rating so I'm guessing about 700 lumens. Since this company uses literally thousands of these in a variety of different modules for commercial (not primarily consumer applications) binning is consistant and QC is carefully controlled. I did check them against a standard 50W halogen bulb - which most people are familiar with or can access.

So equivalent to a 50W household halogen - one of reasons I'm interested in these - they're also intended for residential and commercial lighting installations, an adapter plate is available to flush mount them to a wall or ceiling for recessed lighting and can run 24 hrs/day without overheating - with have a projected 50,000 lifespan instead of the 35,000 that most consumer led lighting is shooting for.

So these are also marketed for automotive off-road use as well as industrial use and are dust-proof and waterproof so they must weigh a ton - right? Yeah - compared to some bicycle specific lights - they might be big and clunky - or not. I use one of these as a helmet light and have no issues myself. But it does dwarf some bike lights - in more ways than one.

That's a NiteRider MiNewt.Mini.300 mounted behind my light. Yeah - that MiNewt's smaller. It also has most of the electronics incorporated in the external battery pack. Yeah - 300 lumens and 4 years ago was also praised as being 'blindingly bright'. It was also marketed as a 'flood' beam.

OK - so this was shot just a couple feet away from a wall with an iPhone. Auto-exposure exposed for the brighter source which was the P7 on the left. So why is the P7 marketed as a 'spot' and the NiteRider marketed as a 'flood'?? Anyway - point being - that P7 ain't all that big and clunky, and 700 lumens is a pretty fair estimate.

Course any battery pack for these would be huge and expensive - right? Again - I've talked to sources at several different companies that supply batteries for other applications and have been playing with matched pairs of several different packs over the past year. Matched pairs just as a performance reference. A vehicle used by the border patrol might run hundreds of watts of additional lighting, a beefed up electrical system, extra alternator and batteries - but we're only looking at a couple lights on a bicycle. Batteries are available in a wide variety of formats, sizes chemisteries and build qualities. Please note that the higher voltage demanded by the light engine also results in LESS AMPERAGE being required. Which means you can use just about anything available on the market as a power source - unlike any bike light requiring a low voltage high amperage power source.

The first two will easily fit in a shirt pocket and that's how I usually run in the winter. Keeps the batteries warmer. Any of them will fit in a Rocket Cage in a bottle holder. In fact 2 of the 6500mAh units will do that and can be linked to make a 13,000mAh pack when longer run-times are needed for multiple lights. Since I plan on running with two lights on during the day - the run-times of the average bike light just doesn't cut it for me. This will.

OK - but is it any good?
I personally found the 35 degree beam nice but really think the beam spread OK but produces issues for both the cyclist and oncoming traffic. There's a hotspot in front of the bike and the vertical light dispersion lights up the windshields of oncoming cars - that's gotta bother them.
The 10 degree is too narrow for my tastes and the 15 degree makes an ideal helmet light (IMO), but is still to narrow for my tastes. Some people may disagree with me. There's also an elliptical beam as well

The settings used by MTBR in their beam comparisons are apparently ISO 100, F4, and 4 seconds. I goofed on this one and used F5 so it's darker than it should be but I don't like their exposures anyway. Lets put some things in perspective. It used to take about 4,000W of halogen light in a portrait photo studio to get shutter speeds of 1/60 sec with ISO 100 film and an aperture above 8.0. So everything is relative. This really isn't tons of light, but the results look OK for a bike light.

Up to this point nothing that really looks radically different from any specialty bike light though. But there are some differences. These units don't get hot. They have a limited lifetime warranty. They'll make excellent back-up lights in the event of a power outage. They're easy to run off an electrical grid run by solar panels.

And - these particular lights will also interlock to form larger arrays. Building an array doesn't change the overall beam pattern (unless you mix beam types) - it just increases the light intensity withon the area covered by the beam. But increasing light output suddenly doesn't require more attachment points or more complicated management.

Here's a comparison of the 15 degree beam to that 15/45 degree elliptical version.

Same vertical coverage - three times the horizontal coverage. That limited vertical coverage is appreciated by oncoming traffic. Apparent brightness on the road drops because the same output is spread over a wider area, but thats easily offset by building an array of multiple lights. There is no spparent drop in brightness to oncoming traffic, but a wider beam is more visible from a wider anlgle. That concept worked out best for me so lets look at some installations on some bikes. In part 2
Attached Images
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led projector lens.jpg (35.1 KB, 24 views)
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LED - Halogen comparison.JPG (34.1 KB, 21 views)
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photo.jpg (91.4 KB, 21 views)
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photo(1).jpg (53.5 KB, 13 views)
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battery pack examples.JPG (96.0 KB, 22 views)
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unlit bike path 2.JPG (97.3 KB, 29 views)
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beam comparison.JPG (31.3 KB, 23 views)

Last edited by Burton; 11-09-12 at 02:06 PM.
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