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| There isn't the start cycle in a LED like there is in a fluorescent, compact or standard. The filaments in the ends of the fluorescent lamps have to be heated to start electron emission. LEDs don't have that. The diodes emit light when DC is applied. Both fluorescent and LEDs have to be used with external controls to the light emitter to limit the current. Both have the characteristic that a small change in voltage applied to the light source causes a large change in current and power.
Most of the time in both CFL and LED the weak part is the electronic circuits used to ballast the current. But I have had CFL fail by breaking the glass tube, several times. I have had CFL fail to run a year, but lately I'm getting more like three years. I write the install date on the base of the lamp so I can keep track. That electronic circuitry is made of the cheapest available parts and they can't stand heat, so an honest seller will suggest they not be operated base up or in a tight enclosure because those conditions lead to a higher operating temperature for the electronics.
Mostly the life clams are for the diodes that do the light emitting, not the electronics which are crucial to the operation. It takes better than military spec circuits to last 20 years in regular operation and the stuff in the lamp bases is generally the cheapest possible parts and won't last nearly that long.
I haven't bought many LEDs, the ones I bought a few years ago were suitable only for a night light because the light level was so low. But for the past nearly a decade I have found CFL even when they only ran one year compared to the claimed several years of life cost less to own and run than incandescent lamps. Even at a thousand hours a 12 watt CFL has used 12 KWH, costing me $1.68 at 14 cents per KWH while the 60 watt incandescent would have used 60 KWH costing me $8.40 allowing me to pay $6.72 for the CFL and I have some I bought for much less, Great Value brand at WMT for break even. And the savings increase when the CFL lasts longer. And that's neglecting the cost of the incandescent lamp and the sometimes difficult replacement over stairs.
The light emitting diode puts out light in a narrow beam. Better tight focusing of that light is one way LED makers increased the light output for decades. The glowing filament of the incandescent puts out light in all directions, but some is blocked by the lamp base though the powder coated glass splays light in that direction too. Many lamp applications waste a lot of the light in odd directions from the lamp, or depend on a parabolic reflector (as in headlights and tail lights) to collect light from the odd directions and put it in a useful direction. LEDs are inherently directional and it takes a gaggle mounted in various directions to get a wide spread of light. Makers often base their light claims on the peak intensity and neglect to report the portion of the sphere actually illuminated so sometimes in applications where general lighting is desired not every LED will do well as they can act like spot lights and won't illuminate the fixture's reflector at all.
Gerald J. | |
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Cree led light bulbs
