Electronics, Lighting, & Gadgets - LED front light stays on dimly when turned off

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.



PDA
DTownDave22
08-31-07, 02:10 PM
I purchased this light combo (http://www.nashbar.com/profile.cfm?category=6000101&subcategory=60001066&brand=&sku=15863&storetype=&estoreid=&pagename=Shop%20by%20Subcat%3A%20Light%20Combos) from Nashbar, a 12.0 LED combo.

I haven't mounted it yet, but I was testing the light out last night and when I turned it off, I noticed in bed in the dark that the LED lights remained on ever so slightly. It sort of looks like it is glow in the dark, but very lightly. I made sure it wasn't just a reflection, as I directed the light toward my hand and saw a little circle. Took the batteries out, and no more light with the light in the "off" position.

Any reason for this?

ModoVincere
08-31-07, 03:29 PM
Probably a phosphorescent glow from the coating on the LED's. White LED's are usually not really white, but a blue led with a phosphorescent coating similar to the inside of a light bulb. This is probably glowing at night.
DTownDave22
08-31-07, 06:06 PM
Probably a phosphorescent glow from the coating on the LED's. White LED's are usually not really white, but a blue led with a phosphorescent coating similar to the inside of a light bulb. This is probably glowing at night.


Thanks for your input. I can see it in pitch dark like a glow, rather than really lighting up--although I am not always able to see that little circle I mentioned--at least not today. I don't know a ton about electronics and lighting, but I'll take your word for it.

supton
08-31-07, 07:30 PM
Simple test to convince yourself: remove the batteries, and recheck.
Jesper64
08-31-07, 10:17 PM
I have the same problem with a 5 LED light that I have. The LEDs are definitely faintly on, if you disconnect the LEDs from the battery the dim glow turns off. I found with mine that if I unscrewed the head so the contacts were broken and then screw it back on the LEDs would be totally off. I did that for a while then just gave up as it was too much hassle. Never quite found out why the it was like that.
Sir Bikesalot
09-02-07, 05:41 PM
My guess is that there's a short somewhere. I got a LED flashlight wet once and it glowed when turned off until I aired it out to dry. If your light came that way new, it could be a defect; I would return for a new one.