I'm curious; when you have a batch of 18650- batteries just sitting in a drawer, how often to you guys throw them on the charger to keep them topped off?
I tend to do so about every 3 months, but I don't really have a reason for that timing, so I wondered what others do.
Never, best resting voltage is about 3.8V as far as I know (if you know you are not going to use them for a while put them in your fridge); I charge new batteries once and before I use them I check the voltage, only if it is under 4.0V (never happened) I would charge them again for normal use, for holiday or other occasions where full performance needed I would charge them to their max.
I store my bike light battery pack at about 45% in an airtight bag in the fridge for long term storage, but that's because of high cost to replace. Individual 18650 cells don't cost much so I don't worry too much about it.
How do you guys go about discharging cells if not through use in the lights?
What I noticed, when I open an old laptop battery: lower the cell voltage better the cell condition,lower internal resistance, more capacity. That means, if a cell is for example 3.2V, surely will be better than an other which is 3.8V.
Interesting table. I guess that is another reason why I'm migrating toward AA batteries, both Eneloops and alkalines. A "discharged" 18650 battery is of no use to me whatsoever if the power goes out and I need it in a flashlight...that is why I top them off every few months.
But aren't almost all laptop batteries in a constant state of being "topped off" when the charger is plugged in? And I know a lot of people who always have it plugged in (including me). Now I am more confused than ever...
Also, we just got out first ActiveE, the all-electric BMW 1-series. You are supposed to top it off every night, and I think (not sure) that it uses Li-on batteries.
Note that best results for long term storage are at or slightly above freezing (Fridge), whereas storing below freezing is not recommended, per the rest of the battery university article.
This does indeed apply to laptop batteries. If you use a laptop as a quasi-desktop & always plugged in then discharge to ~40% & remove it. Even if your laptop has a setting to maintain a persistent low charge the fridge is better. Unless you doing work & can't risk data loss who wants to lose lifetime on a expensive laptop battery?