Battery Life Comparison

What lasts longer- 2xAAA alkaline batteries or 3xSR44 button cells? And by how much?

AAA alkalines are 1250mA if I can remember correctly, while button cells are sig. less

SR44's give about 200mAh, google helps a lot with these questions :

hmm....

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Thanks for the info. How do you calculate battery life from capacity & laser power? Do you use that P=IV formula?

Unscrew the battery cap, press one pin of your multimeter on the battery and the other on the body with the multimeter sent to the amp [or current] setting. If your analog meter gets pinned off the chart or your DMM gets an error, reverse your pin orientations. Read and record the amount of current consumed by the laser while it is in operation. Then divide the battery's total capacity [in milliamps will work as long as your comparison figure: your reading is also in milliamps, otherwise use amps] into your reading and the product yield would be your runtime in hours [which you could then x60 to derive the runtime in minutes]

for example: if my laser draws 530ma from the batteries, and the battery's capacity is 700 mah, then my runtime would be 700/530 = 1.32 hours, which equates to 1h + [0.32x60]m or 1 hour 24 minutes

I don't believe the laser's power has a direct relationship with battery life since theres a middle man called the "driver circuit." I could be wrong though :-/

That doesn't work because of the way battery companies determine their capacity. The more current you draw from an alkaline battery the less capacity it has. Go to energizer and look at the graphs. NIMH batteries hold up much better. And eneloops are the bomb... ;D

oops, been playing with lithiums for so long I forgot all about voltage sag on Alkalines. :-?

well said Gazoo