slowpacer

I remember charging them fully before storing them, but i think they were stored for a few months without use. These battery specs indicate that they hold 90% charge for 5 years but i suppose they don't if they are stored in a case, even if the cable is detached from the light itself.

2_i 

What age are those batteries? I have 40 or so of Panasonic batteries of different age and state of discharge and have not had yet a single die. Now I know that one day they should die, but the only 18650 that ever died for me so far were no-name low capacity ones pulled from two decades or so old laptops.

slowpacer

I think they would be about 4 years old or so. The light was used only a handful of times with these batteries and it worked great but i think the manufacturer recommends using protected batteries with this light, however the ones i have are unprotected.

2_i 

I only use unprotected ones. Those with protection will often fail to fit into spaces, so are in practice less versatile. The typical protection acts as a fuse against high current. Sometimes there may be high temperature or high pressure protection, nothing that you expect for slow discharge.

slowpacer

Thanks for the info. I suppose a protected cell doesn't make sense in this case, since my charger already has high current protection.

2_i 

I managed to bring back NiMH batteries from the dead successfully, using a combination of chargers and the 'Refresh' mode in the intelligent ones. However, when I did it with lithium, they usually went dead again soon.

2_i 

Just another thought. I had a watch type Sony lithium battery die several days after putting it into a device. Sure the batteries were lying around for several years, but something like this never happened to me before. I did some digging around and realized that I was conned those few years and sold counterfeit Sony batteries. I look around my stock and found still another tear strip package with another type of fake coin Sony batteries. Interestingly when I used those batteries shortly after their purchase their counterfeit nature was not apparent, just their premature death provided a cue. Anyway, I am normally very careful when buying batteries, but was obviously not careful enough.

slowpacer

I bought some AA and AAA eneloops from ebay a few years ago and they're still working as a champ as opposed to these that were bought from a reputable online shop so i don't think they're counterfit. My Fenix light is the only thing that uses 18650 batteries, i will probably sell it as hardly ever use it.

sloppy12

NIMH are pretty inscrutable really.. We used to almost catch them on fire over charging them when racing RC's, then we would totally discharge and dead short packs for storage. I only saw a couple of them explode from abuse and other than sounding like a shotgun going off it was way less scary than LIPo fires. lol.

makshima

Just so you know, the protection circuit on Li-Ion batteries serves a couple of purposes. The main reason is to prevent the cell from discharging below a certain voltage. Certain chemistries of Li-Ion batteries need to maintain a certain cell voltage in order to prevent the formation of internal shunts. If the voltage drops too low, dendrites of metallic lithium form within the cell, which is bad for a variety of reasons. One of the potential issues is that during charging, these dendrites can cause short circuits, which can then ignite, causing a condition known as thermal runaway. The protection circuits also prevent over-charging, another potentially dangerous situation. Yes, the protective circuit can lower the amount of current that a cell can push out, but there are protected cells which can push out high current. Also, certain cell chemistries are more forgiving than others.
Bottom line is, if you are going to be responsible and closely monitor your li-ion cells, perhaps unprotected is the way to go. If not, you might be safer going with protected cells.

makshima

Also regarding Li-Ion protection circuits: Many li-ion battery packs, like the ones used for power tools or laptops, use unprotected cells, but wire into the packs protection circuits which momitor each individual cell. If any individual cell drops below a pre-determined voltage, the protective circuit disables the complete battery pack, rendering it un-usable. This is done to prevent battery fires due to the thermal runaway condition I mentioned above. Certain brave (and hopefully knowledgeable) individuals have used this knowledge to harvest working 18650's from dead battery packs. This is not something the average person should do, however. I'm not 100% on this, but I think that the protective circuitry on protected 18650s may also provide this functionality. Should the cell ever fall below the preset voltage, it may disable it to prevent usage. I have many flashlights that run on 18650, 18350, 14500 and other li-ion batteries. Some are protected, some are not, depending on the application. I personally rely on the braintrust at Budget Light Forums. There you will find a lot of people who are far more well-informed that I am who are very friendly and willing to share what they know. If you are looking for sources for batteries, chargers, flashlights, they are a great source. You will also find gear (flashlight, chargers, battery, etc...) reviews and just all around great people. There are even members who have designed and produced (in collaboration with major manufacturer) their own flash lights. I own several of their BLF branded lights and the ones I own are simply incredible.

Leisesturm

Why oh why do people who know jack about a given subject spend money BEFORE they start a thread? Surely the answer for the o.p. was just to purchase a built up battery PACK from a reputable source. Unless you don't need to ask. Homemade batteries can KILL you.