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Laser pointer and battery life

  1. Nov 8, 2007 #1
    I got a 5mW (class 3A), 650nm laser pointer yesterday and it came with 3 AG-3 button cells and over a day, it was on for about 60 seconds, maybe more however I noticed the beam wasn't as bright as it was when I first put it on. Over 30 seconds worth of use, it seemed to dim further until I replaced the batteries with some AG-3s that came with another product and it was noticably brighter. The 3mm white LED wasn't affected.
    The website I ordered it from said its battery duration was 3 hours (it's the 2 in 1 at the bottom). It also said it came with 3 2.5v watch batteries (I thought AG-3 cells were 1.5 volts).

    Why did the button cells lose their power so quickly?
    Why do the AG-3s cause the laser beam to dim instead of allowing it to be at a constant intensity?
    Did the website get the facts wrong?

    Thanks for any replies
  2. jcsd
  3. Nov 8, 2007 #2
    Does the advertisement tell you about the intensity of the beam for the continuous three hour duration?
  4. Nov 8, 2007 #3
    No, but we're only talking about roughly 90 seconds for the beam to half its brightness at this rate, the beam will dissipate by 5 mins not 3 hours.
  5. Nov 8, 2007 #4
    The advertisement is a lie. I have laser pointer running on two AAA batteries and it lasts for less than ten minutes. The laser diode is simply a power hog, inefficient at that.
  6. Nov 8, 2007 #5
    Thanks for your help.
  7. Aug 7, 2008 #6
    Red laser pointers last longer than green ones .
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