On 3 March 2011 06:28, Andre Abelian wrote: > The reason leds are failing or you see discoloration because of led resis= tance > is dynamic it changes right > after turning it on (+ outside temp) and by applying fixed current led li= fe > becomes shorter. > the best way to use leds for lighting is by using constant current not vo= ltage. The strings are sold as "designed" for direct 12V operation. Whetjer they have any sort of current control is uncertain. They may have a series resistor but maybe not even that. They MAY have a formal current control, but even less likely. Yhe ONLY way to get long life is - Drive LEDs correctly at constant current (As Andre says) - Run them in accordance with manufacturers specs and know claimed lifetimes under these conditions - Use LEDs from a reputable "big 5" LED maker OR one using technology from a maker who knows what they are doing. There are many small LED makers worldwide but I am unaware of any that have managed long LED lifetimes by themselves. I'd risk saying that ANY Asian LED maker who cannot show a direct technology link from "big name" LED makers does not make quality product. There is now a substantial cross linking of licences. Some (not all) competent LED makers are (in no order) Cree, Osram, Lumiled/Luxeon. Nichia, Avago, Sharp, Seoul semi, ... The best LEDs operated correctly can have lifetime in the 50k - 100k hours range to 70% output. The worst manage under to well under 1000 hours. If you are REALLY serious then you may want to consider buying quality LED's potting and mounting them to suut your needs and driving them correctly. Replacement will not be necessary for the life of the motorcycle. BUT I have been hit head on by a car when riding with my headlight on. A few LEDs are unlikely to make a vast difference. A colimated LASER may :-). Russell --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .