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Submission + - LED lamps less efficient due to poor design ( 3

Bruce Dawson writes: "LED lamps are very efficient at generating light, but in some cases they draw almost as much power when turned off. This makes their average energy consumption, with some usage patterns, worse than for incandescents. This problem will only be avoided if the market demands better. Write to and insist on lamp power supplies that turn off when the lamp is turned off. We deserve that much."
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LED lamps less efficient due to poor design

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  • If the turned-off LED power supplies were still consuming power, that power would have to be dissipated in a load of some sort, and a heat sink would be required to get rid of the heat generated.

    Unless the LED lamp contains a ballast resistor as a load dumping device, this is very unlikely, unless the LED lamp is of especially crude design.

    The 120 VAC LED lamps I have certainly don't have this problem.

    • This article is about some desk lamp where the PSU gets constant power, and the switch is only cutting the DC power to the LED head. It's the same problem you get with wall-wart style transformers. If you switch off the line voltage to the PSU (or unplug the wall-wart) then it'll stop sucking power.....
      • Yep. It's actually a trivial problem to avoid in this case. You just need to locate the transformer downstream of the switch instead of upstream. That's it. That's all it takes to go to perfect efficiency (when turned off). This implementation is equivalent to manually unplugging the light when it isn't in use, putting it on a switched socket, etc. However the consumer shouldn't have to do these hacks -- the lamp should turn off fully. It's easy. Whether it's likely depends on whether we demand it.

"So why don't you make like a tree, and get outta here." -- Biff in "Back to the Future"