scotty Posted July 31, 2009 Share Very nice I'm interested as well, more so if there is a helmet version. Link to comment Share on other sites More sharing options...
Capricorn Posted July 31, 2009 Share that may be true for that particular driver he is using, and I imagined that was the case.However there are drivers out there which provide constant current outputs for parallel element arrangements. Maybe rev 2.0? Still, very cool looking units. ? Link to comment Share on other sites More sharing options...
Slowbee Posted July 31, 2009 Share would be keen to hear how much the battery packs go for.  To show my limited understanding of lights .....  Can you run the lights on less than 220V? Sure they will be "dimmer", but could you do it? If you do 24hr racing/riding - could you have a car charger for your spare battery pack ?   Link to comment Share on other sites More sharing options...
droo Posted July 31, 2009 Share     Hi Gents' date=' a group responseCapricorn: you are right, in series, if one blows for whatever reason, the whole light will stop working. LEDs typical life span is 35000hrs so you are pretty safe there. I would rather have them in series than parallel, because if one blows in parallel, the remaining 5 will have to handle the same current, (ie the current increases per led) which could blow another, then 4 will have to handle the same current and another could blow and? ...... can you see where this is going   [/quote'] actually, that is incorrect. The total current is a function of the total resistance drop per light element plus what ever resistance is added. With say 3 elements, each element takes only a 3rd of the total current flowing in the circuit. Keep causing elements to fail causes the total current draw to drop by amount of which each element normally takes. I just did a simple calculation of a 3 element parallel resistance circuit,and failing each element in turn results in exactly what which I explained.If what you said was true, we would have had street lights blowing all over the place each time ?a whole neighbourhood gets blacked out. But that is obviously not the case.From a fault tolerant perspective, a parallel circuit arrangement is the best. I would hate to have something where if one goes, it causes the whole system to face plant. that's not a good design.in fact, if one light element fails because of poor manufacturing, and with your current series arrangement, the whole unit faceplants, how do you know which element to replace? you would have remove everything and test each one individually.Ever see those rear bar style brake lights made using LEDs? ever wonder why some of them have gaps where light elements have failed but the whole unit still works maintaining its function? The benefits of parallel circuits.    Actually I think Thys was correct, bear in mind that LED drivers are constant current drivers, so in a parallel arrangement, if one LED blows and stops drawing current, the driver will detect the current drop and then increase the drive voltage to the LED's to bring the current back to the original value, causing the remaining LED's to share the extra current not being drawn by the blown LED.   In your street light example you are correct, but in this case, the lights are being driven by a constant 220V supply that will not change no matter how many lights are connected.   In the rear flashing light is also effectively a constant voltage arrangement, where each LED has it's own current limiting resistor and is driven directly from the battery voltage.  My 2c worth - LED drivers are constant current, and adjust to the forward voltage drop across the emitters being driven. So if one were to blow in a parallel arrangement, the same current would still be delivered to the remaining lights, and nothing else would blow.   So Capricorn, you're right there. But...   LEDs have a very steep V / I curve, which is why a constant current driver is needed to drive them properly. And not all of them are exactly the same. So if they are wired in parallel, the current is split unevenly between the emitters, defeating the point. This basically causes the emitters with a lower Vf to be overdriven and either blow or dim (permanently) due to overheating.   So, it's best to wire them in series, because as Thys said, the chances of an emitter blowing are very slim indeed, and if it does fail catastrophically it'll do so the first time it's turned on. Leaving poor soldering as the only real issue. Which is easily controlled.   My brain hurts now.   Link to comment Share on other sites More sharing options...
droo Posted July 31, 2009 Share that may be true for that particular driver he is using' date=' and I imagined that was the case.However there are drivers out there which provide constant current outputs for parallel element arrangements. Maybe rev 2.0? Still, very cool looking units. ?[/quote'] Â Also true. These are usually used on multichip emitters like the Cree MC-E and Seoul P7, which have much closer tolerances due to being (a) on the same die, and (b) designed to be run in parallel, minimising the effect I rambled on about above. Link to comment Share on other sites More sharing options...
Capricorn Posted July 31, 2009 Share yes, correct Droo, but that would depend on the quality of the driver and how the light elements in a set are selected, ie matched to offer the same impedance to all emitters. However the better driver has a feedback loop for each emitter thus preventing any output from being overdriven and thus essentially maxes out or kicks in an Overvoltage protection which not necessarily takes out the whole driver. Again, choice of driver.? It's all part of quality control in the whole process. Good discussion. Link to comment Share on other sites More sharing options...
Capricorn Posted July 31, 2009 Share crap. i guess i was still bashing my keyboard when you posted that Droo Link to comment Share on other sites More sharing options...
Dirty Twin Posted July 31, 2009 Share Nice work' date=' thysmeades!Are you now the SA agent for troutie-mtb of mtbr forum fame? http://forums.mtbr.com/showthread.php?t=487467http://forums.mtbr.com/showthread.php?t=493687[/quote'] Â Are you also the agent for brighter-lights.com now? Link to comment Share on other sites More sharing options...
AndreZA Posted July 31, 2009 Share Okay, another job for you light boffins. How about a flashing rear light bright enough to use during the day. Maybe with a tiny battery pack you can attach to the seat post below it. Link to comment Share on other sites More sharing options...
Dirty Twin Posted July 31, 2009 Share Are the beam shots from your lights? Link to comment Share on other sites More sharing options...
Dirty Twin Posted July 31, 2009 Share Okay' date=' another job for you light boffins. How about a flashing rear light bright enough to use during the day. Maybe with a tiny battery pack you can attach to the seat post below it.[/quote'] Â BL has one it is a monster. Link to comment Share on other sites More sharing options...
andrewc Posted July 31, 2009 Share Okay' date=' another job for you light boffins. How about a flashing rear light bright enough to use during the day. Maybe with a tiny battery pack you can attach to the seat post below it.[/quote']    Hi Mampara,   Have you checked out this light from CatEye:   CatEye TL-LD1100?   It is seriously bright, even in daylight. I don't have one, but unfortunately the guy I ride behind on Saturdays does! I'm glad that I'm not prone to seizures...   Cheers,   Andrew  Link to comment Share on other sites More sharing options...
AndreZA Posted July 31, 2009 Share  Hi Mampara' date='   Have you checked out this light from CatEye:   CatEye TL-LD1100?   It is seriously bright, even in daylight. I don't have one, but unfortunately the guy I ride behind on Saturdays does! I'm glad that I'm not prone to seizures...   Cheers,   Andrew [/quote']    it need to be as bright as a M3's fog lights. Link to comment Share on other sites More sharing options...
thysmeades Posted July 31, 2009 Share  Very tentative PRICES for Supernova lights. (and build kits)Please do not order yet. I have a massive race coming up and I have no stock of parts so this is for info only. I don't want you guys running off to buy a sigma Karma for a little less $$ and then settling for a lot less (light) I will let know when I am ready. Bear in mind, summer is coming so maybe this is gonna be for next winter only  On the pricing.... I don't have much fat in there with regards to profit. The parts and secure shipping is flipping expensive and it takes about 8 to 12 hours to build a light and battery pack. So, comment all you like if you think it's pricey, I know it very good value. These prices are based on current ex rates and prices at suppliers currently. this WILL change in the future, like all things in life.  I also included the build kits for the diyer out there who wants to build his/her own light and already has a battery pack, and only needs the light head.  Looking fwd to the comments out there.Thys ***Price list removed due to no longer selling ***Chat to Johannes from http://www.brighter-lights.com/ for great lights thysmeades2009-07-31 08:55:49 Link to comment Share on other sites More sharing options...
droo Posted July 31, 2009 Share yes' date=' correct Droo, but that would depend on the quality of the driver and how the light elements in a set are selected, ie matched to offer the same impedance to all emitters. However the better driver has a feedback loop for each emitter thus preventing any output from being overdriven and thus essentially maxes out or kicks in an Overvoltage protection which not necessarily takes out the whole driver. Again, choice of driver.? It's all part of quality control in the whole process.  Good discussion. [/quote']  Multi channel drivers are generally expensive and bulky, not suitable for MTB lights. Also, the multi channel ones often end up driving multiple strings, usually in applications like signage and general lighting, giving a measure of redundancy in case of failure.   Actually, scratch the expensive part. Any decent driver is expensive. (if anyone can disprove this last bit, please tell me where you get the exception to the rule) Link to comment Share on other sites More sharing options...
AndreZA Posted July 31, 2009 Share Thanks Thys, now the problem is which one do I want. Will be between the Triple, Altair XRE or Pocket Rocket.   What is burn time difference between the two battery packs? Link to comment Share on other sites More sharing options...
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