Re: LED fashlights??
- From: "RBM" <rbm2(remove this)@optonline.net>
- Date: Thu, 15 Sep 2005 20:21:22 -0400
Thanks Don, lots of good info there. This "Dorcy" name has come up a few
times. I'll look into it
"Don Klipstein" <don@xxxxxxxxxxxxxx> wrote in message
news:slrndik39e.q0i.don@xxxxxxxxxxxxxxxxx
> In article <19mWe.7001$IC3.6715@xxxxxxxx>, RBM wrote:
>>Anyone have any good - bad experiences with mini Led flashlights,
>>especially
>>regarding durability? Any preferred brands or types?
>
> First, go to:
>
> http://ledmuseum.home.att.net/ledleft.html - what I consider the
> "main index" page for Craig Johnson's reviews of mostly LED flashlights.
>
> Next, go to Target, which has quite a few.
>
> Third: If you want a lot of light, get one with at least one "1 watt"
> or at least one "Luxeon" LED or at least 7 more ordinary LEDs, and either
> at least 3 AA cells or at least 2 C or D cells or a lantern battery.
>
> Of ones that I have found at brick-and-mortar stores, I have had a good
> liking for Dorcy brand ones.
>
> One older Dorcy model that I like, for extremely good durability and
> battery life although it is somewhat weak on light output (one ordinary
> size LED), is a short, stubby yellow one that looks like it should accept
> one D cell. It actually takes four AA cells. I have seen these in a few
> hardware stores and at Sears. It is an older model, and if you can find
> one give the possibility that the included batteries may be past their
> shelf life.
>
> The main advantages of LEDs over incandescent are:
>
> 1. LEDs have extremely long life, usually in the thousands of hours.
>
> (100,000 hours I consider to be on the optimistic side - in a good
> case, white LEDs may have faded to half their "brand new" output after
> 50,000 hours if well-cooled and not overpowered.)
>
> Incandescent flashlight bulbs usually have rated life around 10-30
> hours. This includes variants such as krypton, xenon, and halogen.
> Life will vary with battery type and condition, and is usually rated
> with 1.2 to 1.25 volts per cell (for the number of 1.5V cells that the
> bulb s intended to be used with).
>
> 2. LEDs generally don't burn out, but gradually fade.
>
> 3. An LED does not have a filament that breaks or bends hopelessly out
> of shape if you drop the light while it is running.
>
> 4. Unlike incandescents and their variants (halogen, krypton, xenon,
> etc.) LEDs largely do not lose efficiency when the batteries weaken.
> At half power, LEDs produce about half their full output - and that
> looks more like about 60%. Incandescents at half power produce much
> less.
>
> 5. Incandescents have less resistance when underpowered, so at half
> voltage they draw about 70% (sometimes more) of full current (while
> making about 8-10% of full light) - keeping the pressure on the
> batteries when the batteries are weakening.
> Most LED flashlights have greatly reduced current consumption when
> the batteries weakene enough to reduce light output. The LED
> flashlights essentially go into "conservation mode" when they go dim.
>
> As a result mostly of 4 and 5 (and to a lesser extent somewhat
> higher efficiency of good modern white LEDs), LED flashlights have
> many times longer useful battery life than incandescent ones.
> If you take a good modern LED flashlight and an incandescent one
> that take the same batteries and produce the same amount of light and
> turn them on at the same time and let them run:
> Usually, by the time the LED one has dimmed to looking like half
> its full output, the incandescent one will be at best about as dim as
> an idling cigarette - and more likely will be not visibly glowing.
> After 2-3 times the time it takes the incandescent flashlight to not
> be visibly glowing at all, the LED one is usually still bright enough
> to find your way through the dark with.
>
> - Don Klipstein (don@xxxxxxxxx)
.
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