LED battery life

Being new to this type of light, you are going to have to forgive my seemingly endless supply of dumb questions...but I got to learn somewhere /ubbthreads/images/graemlins/smile.gif

Anyways, looking at my Cutlery Shoppe catalogs, and in some cases what light makers say, these LEDs oughta run darn near forever. In the specs on the Photons for instance, battery life is claimed to be anywhere from 20 - 120 hours. ASP warrantys ever the batteries forever. The Energizer I got says on the package that you get 20 hours of light. Now earlier today I found a really cool site by a member here called the LED Museum. Reading the reviews on there seems to dispute such amazing battery life. What is the real deal? Are the manufacturers stretching the truth just a bit? How do they come up with those numbers?

Thanks.

I would personally put much more trust in the LED Museum's actual physical tests than I would in the ramblings of most marketing and sales folks.

Considering some of the ad copy I've seen, I wonder either 1) where they get their drugs, or 2) what color the sky is on their planet ... /ubbthreads/images/graemlins/crazy.gif



-= MICROSOFT FREE ZONE =-

[ QUOTE ]
Tomas said:
Considering some of the ad copy I've seen, I wonder either 1) where they get their drugs, or 2) what color the sky is on their planet ... /ubbthreads/images/graemlins/crazy.gif


[/ QUOTE ]

Or what laws of Thermodynamics they use /ubbthreads/images/graemlins/smile.gif

Since you're new to LEDs, a few points may help.

-- Incandescent light output shifts out of the visible spectrum as the batteries fade. The bulb still puts out heat, put there is no visible light. The battery is declared dead at that point.

-- LEDs, by contrast, stay in the visible spectrum as their batteries fade. Unregulated LEDs also draw less and less power from the batteries as the voltage drops. This means that they will produce "light", albeit very dim light, for a very long time. How soon you change the batteries is up to your personal sensibilities and needs.

-- IMO a better measure of battery life is how long it takes the light to drop to "half brightness". That's about when I consider the batteries dead. Unregulated lights may burn for many hours, but fall below half brightness in a fraction of that time.

Have fun!

Hello RichardMT,

I think David hit the nail on the head.

I have a LED light that the package states 150 hour run time, the web site states 120 hour run time, and it looses half of its brightness in 24 hours. It did continue to run over 150 hours, but it was very dim and not useful.

Tom

That is the difference between total runtime (which the claims usually use), and useful runtime. First thing I did when I got both a CCTrek and C Crane's 2 LED PR bulb, was run the bulb in a headlamp with 3 Alkaline AAs to check the claimed runtime. At the time I used Radio Shack alkalines. The bulb is electronically identical to the CCtrek, and the Claimed runtime is accurate: 50 hours of bright and 100 hours of useful light. That 1/3 total runtime of bright and 2/3 useful, reflects the discharge curve of Alkalines.

Electronically identical: 2 white LEDs in parallel, Direct Drive. What they are mounted on, is of no consequence.

I have found that PT's runtime claims for the Matrix Module are reasonably accurate. It is regulated, and when it drops out, the light get really dim.

Granted, many manufacturers make outrageous runtime claims. They would even come under "False and Deceptive Advertising."

BTW: I have NEVER heard of something loosing brightness, while I have heard of something losing brightness. Similar spellings with 2 totally different meanings.

(Your loose marbles drop onto the hardwood floor of the classroom, through the hole in the bottom of your desk, and the Teacher loses her mind at another disruption, making you the focus of her wrath.) {happened to me in Fourth Grade.}

Doug's law of LED battery life: "Divide the manufacturer's claimed battery life of unregulated LED lights by 3. In general, this is the point where you will want to change the batteries." /ubbthreads/images/graemlins/smile.gif

There's a bunch of runtime graphs on my site accessable via a link on the Reviews page.