olight s1 and s10 on 16340s

I'm curious...and trying to learn more about this...
My s1 and s10 won't stay turned on running some 2 year old 16340s.
I figure the cells are bad, but they charge to 4.1v, and after 30 minutes, they've dropped a little, but still well above 4.0 (both resting).

When I put them in the lights, they stay on (high) for about a minute then it flickers and turns off.

But the resting voltage after I pull the batt is 3.8/3.9v, which I would expect (from what I've read here) should still power the lights ok?

Any thoughts? Wasn't sure to put this in LED or batteries, since I'm not sure which is the problem...

Thanks!

It is possible that your cells are too worn and they cannot provide enough power for the lights to operate in high modes. Olight S1 and S10 start flickering when the battery voltage goes below 2-3 volts. Your batteries might have high internal resistance which would cause the voltage to drop under load and when the load is removed the voltage rises back to 3.8 V, which causes confusion. Old batteries like that could still be used in low power lights and devices where maximum performance isn't needed.

Thanks Wet... Unfortunately I'm a finance guy, and struggle with electrical concepts.
BUT, I think I kind of get what you're saying. Is high internal resistance caused by age?
And how would I test voltage under load? I do have a multimeter, but only know the basic of how to turn it to the right setting to test the open? Resting? Voltage.

And finally, you're saying those would be safe on low power UNTIL they couldn't hold the charge? (Ie- couldn't stay above 4.0 or so after charging?)

MANY thanks for the help!!!

JD

Glad to help Both usage and old age may make the internal resistance higher, though i don't know which one has more effect on it.

The voltage under load is measured just the same way as the resting voltage, but in addition of being connected to a multimeter, the battery terminals are also connected the load, ie. the flashlight. Instead of using a flashlight as a load, you could also use a power resistor with about 4 ohms resistance to get 1 A current and at least 5 W power rating to handle the heating. My almost new 16340s drop their voltage about 0.15 V from the resting voltage (from 4.15 V to 4.00 V) when loaded with 1 A current, which is about the same current that S10 pulls from the battery in max mode. So their internal resistance would be 0.15 V / 1 A = 0.15 ohm. Higher internal resistance would make the voltage drop even more than 0.15 V, which might be the case with your batteries. Also an almost empty battery has higher internal resistance than a freshly charged one.

Capacity will get lower as the cells are discharged and charged 100s of times. Also keeping the battery in high voltage (above 4.0 V) or low voltage (below 3.6 V) for a long time hurts battery performance more than if it was kept around 3.8 V.

I don't know when it becomes unsafe to keep using an old battery, but at least if the battery gets hot during charging while new batteries stay cool in the same charger, it might be time to recycle the battery.