nah its got nothing to do with the light. i accidentally mixed up 2 NCR18650B with a single NCR18650PF… I would replace the batteries every half hour of use. but since my sisters were using it till the higher high output were low i guess thats where the fault is…
Yes, but how can you explain that the low voltage warning was not activated on the light!. I thought you can’t use K40M “till the higher high output were low” you should get some warning before that! no? Also how do you explain that mixing B and PF cells would cause so huge load and drainage on PF cell!
My advice is not totally safe but it will work 100% because its new battery. Just take 9V battery and connect it with your PF just for few seconds, and do it 5-6 times. PFs are hibrid battery and should handle it just fine. That way you will raise voltage to 2+ volts and yor charger will recognize it. Do it outside and watch carefully on + and - that is in correct order
If the battery won't hold a charge it's dead, period. Trying to recharge it knowing that it won't even hold 1.5v is just asking for trouble. The reason it won't charge up and is self-discharging is because shunts (small short circuits) formed inside the cell; if you do try and force charge it you could put enough energy in there to cause the cell to heat up significantly and possibly vent.
Whatever you do, do it outdoors and remember — don’t inhale if it vents.
What gets damaged is a very thin film of something like Gore-Tex membrane — microscopic pores that let the two different chemicals on either side interact to make electricity flow.
The damage is not a sudden event, it’s a degradation of that membrane, either the texture gets damaged, or crystals grow on one side of it and as they grow they can slowly poke a hole in it.
The sudden event is the result of having had the damage develop inside the cell due to mistreatment — overdischarge, overheating, thermal cycling, dropping, looking at it crosseyed if it’s a fake — or just damaged by being made in dirty conditions where metal scraps or crap can be inside the cell affecting how it behaves.
Lithium-ion cells are not inherently safe. They are safe to the extent they’re made right and treated right.
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P.S., and in reply to
You would be surprised if you met some of the people who contributed to the best tech you can buy hereabouts.
Trying to preserve a battery that has likely been damaged and can fail spectacularly isn’t something I would do. With battery prices being what they are these days you can replace it for around $6, which is less than a decent burger.