Max Discharge Rate for L91 Batteries?

recDNA

Flashaholic
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Jun 2, 2009
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I just measured the amps at the tail of my Javelin (XP-G R5 single mode) with 2 X L91 batteries and found it starts at 2.3 amps and drops to 2.25 amps in 60 seconds. I know that Everready describes the max constant discharge as 2 amps however this battery is protected with thermal protection (PTC) and venting.

Is operation of the flashlight under described conditions dangerous?
 
i have seen other tests (not here) where people overdrove the bunny lithium cells, and they didnt even KNOW .
guess that makes you that far ahead of the game .

They were noticing that things were not going as fast , with the lithium cells vrses ni-mhy , or even alkalines at first.
they would conclude that the battery sucked, that is wasnt capable of putting out the power.
It didnt stop them, they just kept doing thier testing over and over again, so i assume the protection was doing its job, and not causing even more problems.

continue to use it when you know it is over spec and kicking in the PCT fixer thing, knowing that some heat at the PCT is going to continue to add heat to the cell?
i say no , not in the Boost curcuit , because as the voltage drops the boost curcuit tries to draw even more current, situation never improves, as long as the current is maintained.
might not be so terrible in the 3xDD type stuff where the internal battery protection will become the DD resister :thinking:

will they get away with it in flash units? probably because the spike in current doesnt last continually. Will they realise what the heating was , and why it got hot when they wouldnt let up on it? mabey some day.

will it blow up completly? well the protection is trying to prevent that. prevent the high current from overheating the cell, on the other hand all enclosed the protection fixer is still putting heat in the cell.

Have people blown up bunny lithiums in high current devices. YES. there has been at least 3, A 1cell Cell phone charger, a 2cell cell phone charger, and a toothbrush ??

will i myself screw up and try and use them where it is way over spec for them. YES, because i keep thinking they can handle it. Ugg thanks for the reminder again.
 
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I honestly have no idea if there is a true safety limit somewhere beyond the manufacture spec on this one. There may be another solution...

Have you considered moving in the direction of a pair of NIMH cells that could handle the current without any danger?

Or would the lower input voltage be counterproductive? (I'm not sure how *much* boost you can get out of that regulator with lower input voltages, or I guess the question is, where is the shelf where it drops off rather than continues to climb in current draw with lower input voltage?)

Most NIMH AA cells can handle 2-3 amps without much trouble, getting some quality high current hobby style cells or LSD cells will help you hold better voltage under the load.

Eric
 
NiZn cells have a voltage about 1.7 volts...

Under load of 2 amps?

Anybody know where I can find a spec sheet on Powergenix AA NiZn and Tenergy AA NiMH? Both say "high power" but neither shows a real spec sheet like Everready does.
 
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Under load of 2 amps?

Anybody know where I can find a spec sheet on Powergenix AA NiZn and Tenergy AA NiMH? Both say "high power" but neither shows a real spec sheet like Everready does.

I don't have a spec sheet but have done numerous test with mine. I've put them in Flashlights that draw over 4 amps of current and seen them do it while maintaining 1.6 volts (usually a little higher) much like the Eneloops will maintain 1.2 under high draws. I took a Nizn out of my tooth brush after using it for over a week and it still provided over 4 amps and stayed at 1.6 volts.
 
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