Runtimes: Intermittent vs straight?

Dude Dudeson

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Is there a thread about this anywhere? EDIT: This is an LED specific topic, for me anyway

I swear I'm getting way, way more runtime from my lights/batteries than any runtime figure I've seen.

Bought my 6PL early last June. Played with it a lot, and used it a lot.

Bought my M60 in late July. By then I was pretty sure I'd put about 3 hours on the Surefire 123's, so I put a new set in figuring the M60 would have killed the used cells quick, and also wanted to get an accurate idea of my M60 runtime.

At that time I had become aware that the 6PL's "11 hour" runtime claim was BS, and knew I could expect around 4 "real" hours. So I was keeping a decent mental tally on my usage.

I wished to do the same with the M60 (although by that point I was fairly trusting of Gene's figures).

Now back to those original Surefire cells - shortly afterward one of them went into my Romisen RC-N3 II. By the way, I actually labelled the original Surefire cells with a Sharpie, so there's been no mixup. The first set of M60 cells were labeled too.

SINCE then I've put at least an hour on the Romisen on high, and probably another hour on low. That one cell just isn't dying... (for those who don't know, that Romisen puts out about the same light as the stock Surefire P60)

And the batteries in the 6P/M60? I'm guessing at least 120 minutes - I did a 30 or 40 minute test for heat right when I got it (5 mile night hike, intermittent usage going out, left it on the whole walk back, walking slow, stopping to light stuff up, etc).

That night was nearly 4 weeks ago, and I've done that same hike about 6 more times since then (but no big heat tests, longest straight runtime maybe 10 minutes tops). Also a lot of quick uses around the house.

So my very informal, unscientific observations seem to indicate that intermittent usage yields much greater runtimes - any hard or anecdotal evidence among CPF'ers that agrees?
 
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Narcosynthesis

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Oct 28, 2008
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105
I can't provide any concrete sources, but yes, to my knowledge intermittent use should give you more runtime out of a battery than leaving it constantly on...

The idea behind it as far as I know is that intermittent use allows the batteries to 'rest' between uses - the chemistry gets some chance to sort itself out and cool down after being put under strain. That was an exceptionally poor explanation of chemistry and electrics, but is the basic idea.

At the same time, LED's also work best cool, so intermittent use means they aren't running hot for as long and stressing them and the power source as much.

Manufacturer ratings are always interesting too, as many seem to test their lights in a very efficient fashion ;) so constant runtime usually varies between manufacturer and home testing, then varies again in normal intermittent use too...
 

Badbeams3

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Sep 28, 2000
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Agreed. Intermittent use extends run time. Batts given a chance to cool in between use do better.. Many a runtime test is done using a cooling fan. But either way rest run rest run yields a longer total run.
 

Illum

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The idea behind it as far as I know is that intermittent use allows the batteries to 'rest' between uses - the chemistry gets some chance to sort itself out and cool down after being put under strain. That was an exceptionally poor explanation of chemistry and electrics, but is the basic idea.

The LiMnO2 chemistry have been known in the past to have unbelievable yield in capacity after resting for only a couple hours or so. I'm not sure about LEDs but back when I use my G2 in its stock form under intermittent use that "50 minute" runtime actually lasted for a week when used only ~10 minutes/night.

the original concept in the CR123a was to provide moderate current for a long period of time, whould wouldn't seem too surprising to be used as a power supply for LEDs :whistle:
 

Egsise

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Is the output still the same as with fresh cell or has it dropped?
Does the output drop in use?
Could you measure that with a lightbox or ceiling bounce and lux meter?
 

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