I had recently bought 4 3400 mAh 18650 batteries that I planned to use on a new flashlight,not ordered yet,but have since bought another light that needs a High Discharge Rate 18650,for which I bought a pair of Sony VTC4’s for.
The 4 brand new 3400’s have been sitting in their boxes for maybe 3 weeks……how long can they sit before I need to check them with a DVM or charge them? They have never been charged by me yet,so how long can they stay”asleep”? Thanks,HB
Afaik they can sit months and they’ll be just like new. Or rather wait for HKJs answer 
It’s best not to let them get below 2.8v
Couple of links from Battery University might be useful reading.
How to store batteries
How to Prolong Lithium-based Batteries
New cells should have a storage charge of about 40 - 45% storage charge when you receive them. I have cells that have only gone down a few % over a couple years. At 100% storage charge, there will be faster self-discharge and cell life goes down more rapidly. Cold storage helps preserve cells.
Laptop batteries usually have a chip in their housing that creates a slow drain so they should be checked once a month or so if stored at 40%. Not sure if the added protection circuits for individual cells create a drain.
Easily months, if you keep them cool and dry then it is years.
Cool does not even have to be a fridge, but 5C is slightly better than 20C, when you get much above 25C the batteries starts to degrade.
Thanks everyone! HB
i load every day if i use my batteries (i4 pro jetbeam) on full (3 led green on top charger)
bad ore good ?
Of actual capacity? (In other words, fully charge, then drain 60-55%?)
Of nominal voltage? (In other words, for a 3.7 volt 18650, store at 1.48-1.665? Those are below 2.5, minimum recommended.)
For me, KISS means that a Li Ion of 3.7 should be stored at _ resting volts?
What is the fun in not using your flashlight? You could try to avoid charging all the way up to the last bar. That would prolong the life of the battery a bit. But don’t sweat it. Get a new battery now and then, if you don’t think it holds enough charge any more.
What you also can do is to only use one battery, and store most of your spare batteries cool and dry at only a partial charge, as mentioned above. A battery from a decent brand should last at least a year, possibly more, before you notice that it lost capacity, even if you charge it every day. Especially if you don’t max out the charge every time.
Actually it would be nice if chargers had a “long battery life” setting, that made it charge only up to say 4.1 volts, instead of 4.2 volts. It would still keep around 90% charge, but you could expect it to last up to twice as many cycles.
I now have an adequate (and always growing) collection of lights what I continuously rotate into and out of usage.
So, while I have a good supply of batteries, I tend to reuse/discharge/charge the same few (to wear them out) and have the bulk of my supply in storage to slide into usage. In an emergency, the stored ones will be pressed into service (even with minimal stored charge).
Make sense?
So “Store charged at 40-45% of what?
40–45 of capacity if charged to 4.2 volts.
And that is somewhere between 3.9 and 3.8 volts. So I’d say 3.9 to leave some room for self discharge. This might perhaps vary a little between different battery brands. You could use a hobby charger to figure out the exact capacity and monitor the discharge. Or preferably the charge process.
I got 3.8-3.9 volts from here:
It seems to match partially numbers from:
There it is also mentioned that 3.92 volts is the optimal charge voltage for longevity, but it gives only half the charge compared to a full charge up to 4.2 volts.
So that seems to confirm 3.9 volts again.
But I’d say that it is a bad idea to fully charge and then discharge down to 3.9 volts. It would be better to stop charging at 3.9 volts.
Probably my poor searching methods, but you just answered a burning question.
May the Lights Be With You!
This seems to be right if I can rely on the Soshine SC-7 Charger I have. At 60% I switched off the charger (going by the LCD screen), the voltage is around 3.9v. I know the voltage agrees wtih my DMM, but I cant say the same for the percentage reading, I have no idea how it knows that, or more likely, ‘guesses’ . But at 50, its also reading 3.9v. In fact it seems to read 3.9v for a large chunk of the % on the ones I fully charged.
OK, thanks! It seems I might have to adjust down a little bit. 3.8 volts, or even 3.7 volts, seems better than 3.9 volts for longevity. But 3.7 volts might be too low for some batteries. But it is obvious that this is an approximation. The actual voltage for 40-45% capacity may vary between batteries, and even for the same battery depending on the discharge current.
I’d still use 3.9 volts, even if that perhaps isn’t optimal. Then the battery would still have a useful charge, self discharge wouldn’t be a problem, and still the longevity would probably be greatly improved.
I have my NiMh LSD batteries for emergencies, or my vintage kerosene pressure lanterns…
Also I have Li-Ion chargers I can use from 12 volts, from the car battery, if the car is used. Don’t want to drain the car battery…
But I agree, for emergency readiness it might be an even better comprise for some to store at 4.0 or even 4.1 volts. And get new batteries now and then.
I’m lazy. I know the ‘formulas’ for storage but I ignore them because I think they are not only a little ‘anal retentive’ but a big waste of time. Store them in the freezer, the refrigerator, the basement, in the dark, on their side, standing straight up, on the north side of the house, charge or drain the batteries to achieve the perfect X.X voltage - I don’t mess with any of that. I’ve never had any issues storing these batteries. With my AW IMR’s and AW LiIo’s I just charge them on the Pila charger (unless I’m testing them - then I use my ICharger 3010B) and stick them into one of the foam lined Pelican cases and I’m done. No fooling around with them. They all come off the Pila @ 4.17v. I usually check the voltage of anything that has been sitting for a while before I use it but like I said, no problems at all. After a few months (4-6 months) I usually see a .05v -.08v drop and I find that more than acceptable. So…………I don’t bother with it. If the battery is going into a high drain device, I might throw it on the charger for a few minutes to ‘top it off’. I have a LOT of AW’s and one would think I would have had problems by now because I don’t follow the ‘formulas’. I’m still waiting to see the first problem. My 2 cents. 
EXACTLY!!
i using the flashligt ….full charge batteries give so that little more power for light 8)
I mostly do too for exactly that reason. I could keep adequate lighting for months without even breaking out my solar charger or UPS. I'm sure there's been some degradation, but so far the only cells to go bad have been two Keeppower 14500's.
I also have a few brand new cells that I've never charged, plus a bunch of other new cells still in laptop battery packs, but I don't really count those since they're not in rotation yet.