<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Gransee:
At what point with a particular flashlight do we feel we need to replace the batteries? I guess that would be the real "usable light" limit.<HR></BLOCKQUOTE>
I change flashlight batteries for the purpose of maintaining certain level of brightness that is usable to me from a particular flashlight. Pretty much the same reason I replace a degraded bulb or lamp with the same "watt" rating to maintain a certain level of brightness in the house.
Running flashlight to the point of blackout will only happen if replacement battery is unavailable.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by WarrenI:
When you first bought your light, you were probably impressed how bright and usable it was. I don't think you would have been impressed if you could only read a newspaper with it. Realistically, I do not think this is a good gauge to say that the light is still usable. <HR></BLOCKQUOTE>
Right, there has to be a certain acceptable level of usable brightness from a particular flashlight. For Surefire or LW4000 only capable of brightness, or 80% of its xx number of hours of brightness rated by manufacturer, to the level of reading a newspaper 1ft away is not what the flashlights are designed for and there's got to be an anomaly or something wrong somewhere for the flashlights to behave this way. On the other hand will it be okey for a Photon for 50% of rated xx hrs. brightness to get down to the level of only illuminating a newspaper 1ft away as acceptable level of brightness because it is not designed for and advertised to be able to outshine or comparable to the brightness use of Surefire and LW4000.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Harrkev:
1)Insert new batteries and measure light output after three minutes (let the surface charge dissipate).
2) Usable life will "end" when light output is 50% (or maybe 33%) of initial reading.<HR></BLOCKQUOTE>
I tend to agree with Harrkev. Beam brightness will degrade as battery runs out of juice. Flashlight use is not measured by how much juice battery still has left in it but how close is beam brightness to its prime brightness.
How do we do that? Measure with a lightmeter or current/volt meter and graph flashlight's beam output.
Suppose a flashlight started with a current reading of 200ma, is it safe to say that when it reaches reading of 100ma light is no longer usefull? I mean will the numbers (mA or lux) correspond with my visual perception?
I guess it's going to be a case-by-case basis depending on flashlight's model.
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