Do Li-Ion batteries get better as they are used?

[Black Rose]

I know with NiMh cells that they get better after a certain number of charge/discharge cycles.

Does the same hold true for Li-Ion cells?

The only reason I ask is that while I have been home the last couple of days I have been doing some runtime tests on some new 16340 cells I have. After only a second charge, the runtimes almost doubled.

I charged the cells before the tests were done to make sure they were topped up.

In the first test, I managed 44 minutes and 28 minutes before the protection circuits on the cells tripped (630 mA initial draw).

I recharged the cells and tested again.

On the second test (same flashlight) I got 1 hour 14 minutes and 1 hour 18 minutes from the same cells before I stopped the tests myself.

Does this make any sense?

 

[Twinkle-Plank]

I think that you are meant to discharge and recharge Li-ion cells a few times before they reach there peak capacity.

 

[325addict]

From what I understood from batteryuniversity.com this is not the case. Cycling them to make them better should not help, only helps to make them WORSE as these batteries don't like to be drained fully. Better make 10 half-discharges than one full (and by full I mean: not dead, but until the protection kicks in).
Runtime tests with these batteries should not be made too often, as it reduces the cycle life enormously.
Running them into the protection every time, could decrease life to 20...50 cycles as I read before.
That's why I do this only 2 times in order to pair them, AND in the same runs to measure capacity, so I know runtimes on the numerous lights.

Timmo.

 

[VidPro]

certannly dont cycle them the excessive way that they will do with ni-cds for RC, and certannly dont ever "cycle" (vrses use) them purposfully when in series, but if its been parked (unused) and it doesnt deliver any usable capacity under a load, you could try and discharge it low, then recharge it, and see if it gets better.
there are times when it does, and times when it doesnt, and (again) i cant define any set parameters for it, just like the age thing. someatimes it do and someatimes it gets worse, and it doesnt nessisarily ever make sence.

i swore one day i would figure it out, but taking 6 month between charges to test it, takes for friggen ever. some cells (usually of the same type) react good, and some react badly, and some dont even make it the 6 months
you see sometimes the batts you get have been sitting around before we get them, sometimes they have sat around longer than they are even good for , meaning they sold us batteries that are already neer dead.

i always wonder how in heck a store with 1000+ of these things can even check them, or have them properly stored, our Frys had so many so badly stored, they re-did the entire rack, and must have tossed out 1/2 of thier stock. (bet those sell cheap on fleabay)

if its working good, and getting good capacity, then just use it, but if it sucks you sure have nothing to lose, and more information about it would be usefull, like what you just saw.

 

[Black Rose]

I thought it was a bit odd and I hadn't seen it mentioned here, that's why I asked.

These were new cells I just received in the last few weeks.

2 each from different brands.

With brand X, one cell didn't perform well the first time, but the second cell was great from the start.

Same thing with brand Y (which came as a pair).

After only two charge/discharge cycles, they all work well now.