Re: new LED torch (flashlight) bulbs more efficient?

From: Don Klipstein (don_at_manx.misty.com)
Date: 03/23/05 

Date: Wed, 23 Mar 2005 05:34:44 +0000 (UTC)

In article <xax%d.6061$uw6.4861@trnddc06>, Anthony Matonak wrote:
>ghbt wrote:
>> Do the new LED torches (flashlights) actually give more value for
>> money from the batteries ( in terms of illumination per cost of
>> batteries) than the previously developed small and bright xeon bulbs or
>> the older ordinary torch bulbs?
>
>Yes. A White LED is about as efficient at turning electricity into
>light as, say, a 60W 120V incandescent bulb. This is many times the
>efficiency of the little incandescent bulbs used in flashlights.

  I would say a little different...

  The little bulbs used in flashlights, despite a significant "economy of
scale" (more than one thereof) for incandescents, often achieve similar
efficency - mainly by being designed to "run hot" to the point of design
life expectancy mostly in or near the 15-30 hour range. Some are designed
for life expectancy as short as 5 hours.

  LED flashlights mostly have similar enough efficiency with fresh
batteries. They mostly differ in performance from incandescent
flashlights by having efficiency impaired less by draining of the
batteries than that of incandescent incandescent ones are by draining of
the batteries.
  Yes, this is significant - take two flashlights, with equal power
consumption from fresh batteries, equal light output from fresh batteries,
and one is LED and the other is incandescent.
  What I consider typical is that the LED one will be quite useful, with
20-40% of its output from fresh batteries, while the incandescent one at
that point usually appears completely dead in "normal room light" and
glowing as dimly is a cigarette sitting in an ashtray in a situation dark
enough to see this!

 - Don Klipstein (don@misty.com)

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