In the past, I’ve had to discard many flashlights because alkaline batteries would have started rotting inside them. I’ve used my mobile phone flashlight for a few years now, but trying to decide what kind of flashlight I will buy this time … my first serious flashlight!
I’m planning on getting something with a user-replaceable lithium-ion battery. User replaceable so that in the future I can give the flashlight a new lease on life by buying a new 21700 to put inside. But also because I’ve seen many devices with such batteries start bloating. I’ve also had such batteries fail after being left empty for too long.
Perhaps this is the wrong community to ask about how to care for an infrequently used flashlight, but … how do you care for your lithium-ion battery powered flashlights? When not in use for a very long time, do you remove the battery? Do you charge and forget when storing them, or regularly empty and recharge?
Remove from light, get the battery to somewhere around 3.7-ish volts if it isn’t already, place battery in the little plastic box they ship in, place box in cool, dry part of the house where they won’t be knocked over and every 6 -12ish months take it out and cycle the battery once or twice.
I have some batteries I vacuum sealed for storage but it was only because I just got the machine and I was vacuum sealing everything I could find lol. I vacuum sealed an entire antique rifle fully assembled that day.
Keep the batteries charged to 100%
Keep them in the flashlight.
Keep your lights in a dry safe place.
Keep extra batteries (i.e batteries to be used when necessary) in specialized battery storage container.
This will ensure you have a working flashlight at all times (isn’t that the point of all this.)
Yes its try by storing them at 3.7v means the batteries will last longer but in an emergency you wont have a working flashlight.
Not having a working flashlight when you need it may mean the difference between life and death.
Bottom line, don’t waste time and energy thinking about how to make a $5 battery last an extra year.
Enjoy your working flashlight with charged batteries.
Unused cells, I capacity-test them which leaves them at 4.2V, and I just store them in plastic cases. I don’t get all jazzed about “storage voltage” and keeping half-dead cells if only to gain single-digit longevity on the cells.
Come-with cells in lights I don’t use but rarely, I’ll remove the cells and store them along with unused cells.
Rarely-used lights, I remove any cells and store them.
Occasionally-used lights, I might keep the cells inside, but physically lock-out the light (ie, unscrew the tailcap if doing so actually breaks contact), along with the tailswitch if any turned off.
Lights “in rotation” every so often, I’ll leave the cells in, but lock out the light.
“Coffee-table” or “nightstand” lights, they’re locked’n’loaded.
Some people get crazed about storing cells at 3.6V in airtight refrigerated containers blessed by an ambidextrous shaman on the night of a full moon. Have at it. Me, nope.
Just avoid parasitic drain by locking out the light, and keep the battery level topped up to 90% is enough.
If you completely drain a battery and leave it for a relatively long time, it’s dead. Other than that, Li-Ion is pretty robust.
Also agree with above posts. Don’t baby your battery and have a half dead light when you really need one. The chemistry inside ages anyway and even if you don’t use it, it needs to be replaced after a couple of years.
I have 2 Enerpower 18650’s from the time i bought my first High Power Flashlight in 2012 (Fenix TK35)
They still work fine. Should i no longer use them because of the age (11years) ?
I store batteries between 3.6-3.7V, sometimes just over 3.7, in their plastic box in the dark as already suggested, basically to protect them from being shorted out and from knocks, and to mediate any changes in temp. I live in a moderate climate though which makes that one easy.
In emergency torches i keep the batteries 4.05-4.1V to take the edge off deterioration from being fully charged while still having plenty of charge.
I just stay away from extremes basically, full and no charge, high and low temperatures, and quick changes in temperature.
Definitely, as already suggested, pay attention to parasitic drain. That’s the main cause of my battery issues in general.
I have a pair of 10ish year old purple Efest 3100 batteries that i forgot about and found again last year.
No idea what voltage they were left but were around 3.8V when i found them, did a capacity test and they both exceeded 3100mAh @ 0.5A discharge.
Not really sure what that proves though other than there is some tolerance in storage conditions.
Ohh, ambidextrous! I though it was an ambivalent shaman, which is harder to find than you would think.
Get a “smart” charger that can do capacity tests. You can also go for resistance tests, but on hotrod cells, the connection to the cell itself can be almost as high as its internal resistance, and even multiple tests in quick succession without touching the cell itself will give you results all over the place, so I rarely if ever bother.
But the capacity test is critical. Know Your Charger. My Opus tends to be more critical than other more “optimistic” chargers, so a 3000mAH cell might test at about that on other chargers, but maybe 2900 and change on mine, which is fine. It’s consistent. I’ve done “refresh” cycles (ie, 3 cap-tests in a row) and all the results came out within a 50mAH spread, and a few were pretty much identical numbers.
Learn what the cells rate at when new. After torturing them in lights a few years, measure again. Capacity might be a bit lower, but not too much.
Crapcells given away free with gas-station sushi might rate 300-500mAH, meaning they were scavenged from the garbage and rewrapped nice’n’pretty to entice suckers to buy what’s probably a craplight, too. Those should be dumped.
But I still got ancient panny-As from laptop-pulls that rate pretty high. As long as they don’t get too warm when charging, I’m happy.
Ultimately, you do you, but as long as I can squeeze some life out of “old” cells, I will.
My EDC and a few other lights that get used regularly are kept at full charge and recharged when they drop to about 3.6 volts. They all have a firmware battery charge indicator.
Several other lights that do not get used with regularity and stored with a fully charged cell just in case something happens and light is needed. As others have said, so what if their life is shortened a little, at least they will be useful if needed. Of those lights, those withe-switches are stored with the tailcap or head slightly loosened to eliminate parasitic drain. Maybe once a year I check the cells charge and recharge if I feel it is necessary. I do not cycle them through a discharge and recharge. I see no point in that.
FWIW, on Nov 28, 2019, I placed 4 randomly selected Samsung 30Q 18650 cells in a plastic storage box and put the box on a shelf in my workshop. If you are not aware, those are quality cells. The voltage of all 4 cells was 3.81. I just went and checked the voltage on those cells. The meter indicated 3.77 or 3.78 volts. After four years of storage with an insignificant voltage drop, I am happy. They have not been discharged or recharged during that time. No special treatment. In summer the shop temperature might reach the mid 90’s and in winter down to the mid 40’s.
Pardon my ignorance, but would this be a ‘30Q’ series (quick Google searches don’t get me much, here) … I’d be looking for the 21700 options most likely, and happy to buy quality products.
If they’re sitting for less than a few months, just charge them before. If more than that, charge the battery to 3.7 as that’s the most stable voltage and recheck at least every 6 months or so.
If you want to immediately use a light after a long storage period, use eneloops or lithium primaries in it.
That only happens with alkaleaks. There is no reason to use them vs eneloops or lithium primaries, basically ever.
Speaking of all this, I tend to drop them now and again, a 3 to 5-foot fall, usually onto the wood floor. Is any special checking warranted other than visual inspect, popping into the charger and confirming things look OK (voltage and resistance)? Should I be wary of these cells as I put them back into service?
Generally speaking, I would not drop batteries. If you are six feet tall, five feet would be shoulder height. I am not sure what batteries would be doing way up there.
Unless you they are falling off a shelf that is five feet high.