Stock piling Lithium Ion Batteries?

Zeva

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Hello, I was wondering is it a good to stock pile them as in buying 20 or so will the life of them die? Or would it be ok? Finally, How would you store them the best? I was wondering this as someone told me that DX will stop shipping L-ion batteries over seas? is that true? If not i guess you can ignore the first two questions! ^.^ Thanks!
 

Niconical

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I think I read in a thread somewhere that even if unused they will have an expected life of no more than 4 or 5 years before they degrade to a level that makes them not usable, but I can't remember where I read it so don't take it as fact unless someone else can confirm.
 

amigafan2003

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As above, don't buy more lions than you can regularly use.

Any torch that sits for a couple of months or more is best to have a primary in it.

Also, remember that a lion battery stored at full charge at room temp permanantly loses 20% of it's rated capacity a year. That's capacity - not charge. So a 2500mah cell will only be capable of 2000mah a year later. Try storing lions cells in the fridge when not in use. A fully charge lion cell stored at 0c only loses 4% capacity over a year.

Your best off buying the cells you will use, use them for a couple of years, dispose of them (responsibly), then buy some more. And only buy them from retailers that sell a LOT of cells - you don't want to be buying lions that have already sat on the shelf for a couple of years.
 

how2

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Buy the batteries that you need to use on a daily basis. Primary batteries have self life of 10 years. Rechargeables have a life of 5 years or less.

Don't forget battery capacity will always increase over time. The highest capacity 18650 battery at DX is about 3000mAh.(printed). In a years time this could go up to 3700mAh,

I have 6 rechargeable 123 and 2 18650. I want to have 12 and 4 respectively. I am in the process of choosing.
 

bluecrow76

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Also, remember that a lion battery stored at full charge at room temp permanantly loses 20% of it's rated capacity a year. That's capacity - not charge. So a 2500mah cell will only be capable of 2000mah a year later. Try storing lions cells in the fridge when not in use. A fully charge lion cell stored at 0c only loses 4% capacity over a year.

Thanks for posting that... I'm sure it's elsewhere also but I've never wandered across it before.

I have probably close to 50 unprotected cells that I top off every six months. I rotate my protected cells in use and top them off every now and then. I'll have to move the unprotected cells next to the solder paste in the fridge... hope the wife doesn't mind! :whistle:
 

bdancer

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The Battery University has a page on this, and according to it if you store Li-ion batteries at 40% capacity and near freezing, the recoverable capacity only drops 2%/year. If you store full batteries at room temperature, it drops 20% a year.

Assuming a linear capacity decline function, this means that stockpiling for 10 years at full capacity and room temperature will result in batteries with capacity of 10% their original capacity. If you store them at 40% capacity and near freezing, however, in ten years you'll still have 82% capacity, and after 20 years, 66%. Not too shabby; might be worth it if future availability seems uncertain.
 

PeaceOfMind

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The Battery University has a page on this, and according to it if you store Li-ion batteries at 40% capacity and near freezing, the recoverable capacity only drops 2%/year. If you store full batteries at room temperature, it drops 20% a year.

+1, I store a (very small) stockpile of Li-Ions in the fridge, in a sealed bag with some dessicants, at 40% charge level.
 

T0RN4D0

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If you dont mind discharging them to storage voltage, and keeping them in your fridge then you can buy a few more then you need. Stockpiling a shitload of them is bad idea, since li-ions degrade weather you use them or not.
 

Zeva

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Thanks guys! also does anyone know about weather if DX will stop shipping them?
 

matt_o

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What voltage would be considered 40% charge? Is that below my AW's protection circuit? Also how can you discharge them besides in a light?
 

amigafan2003

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Thanks guys! also does anyone know about weather if DX will stop shipping them?

They wont stop selling or shipping them - they'll just have to be stricter on packaging and labelling.
 

Bullzeyebill

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I just use mine, and do not notice big difference in a four year time frame for my LG's and generic 18650's. They justr keep working, working and working, just like the Energizer Bunny. Only failures I have noted are those cells that I have under discharged, like well below 2 volts, These are unprotected cells.

Bill
 

PeaceOfMind

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What voltage would be considered 40% charge? Is that below my AW's protection circuit? Also how can you discharge them besides in a light?

No, of course not below the protection circuit, otherwise you'd only be able to use 60% of the battery (or less since voltage sags under load). See this chart, courtesy of AW:

Voltage vs Charge Status:

4.2V – 100%
4.1V – 87%
4.0V – 75%
3.9V – 55%
3.8V – 30%
3.5V – 0%


So somewhere in the 3.9V or slightly below area would be ideal. Just don't overdo it. I believe AW batteries generally ship about 40% charge, or you can just discharge them in a light or other device, since that is easy and safe.
 

Zeva

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Thanks a bunch! if DX doesnt stop shipping to US then theres no purpose to buy more! i got 4 more 16340s comming! ^^ does anyone happen to have where DX put the new info about shipping l-ion bats?
 

rmteo

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What voltage would be considered 40% charge? Is that below my AW's protection circuit? Also how can you discharge them besides in a light?

Most hobby chargers have a STORAGE algorithm that will do this for you. They will charge (or discharge) automatically to a storage voltage - typically 3.30V for LiFePO4, 3.75V for LiIon and 3.85V for LiPo.
 

fyrstormer

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I have as many l-ions as will fit in my flashlights at once, plus two spares. No sense keeping more around than that, since they're just going to go bad anyway.
 

old4570

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Dont think so [ DX ] bread and butter sales to them ...

+ Its not a shipping ban but rather how the batteries are packaged for shipping .

A lot of ebay sellers are now putting them in those little plastic storage boxes .
I dont know if DX will do the same or not .
 

45/70

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A lot of ebay sellers are now putting them in those little plastic storage boxes .
I dont know if DX will do the same or not .

Great, now that I have a gazillion of those boxes. :sigh:

As to the OP, I would say no, to stockpiling Li-Ions. As has been pointed out, they degrade whether you use them or not. That said, I have a pretty good stockpile myself. It's due more to having so many different sizes though, than actually trying to stockpile them.

Also, concerning the general degradation of LiCo Li-Ion cells, I have never disposed of/recycled a Li-Ion cell. I have cells that are 6 years old, and they are all above 80%. The time will come soon, probably within the next year, when I have to recycle a few. I do keep my cells in the fridge, charged to ~40%, when not in use, but all get used. I doubt any of these have more than the equivalent of 100-150 full cycles on them, most far less. I try not to discharge cells to less than 20% remaining capacity, and usually stop at about 40%, or less. It is noteworthy that the cells that are showing the most aging/degradation, are unprotected cells that have routinely been used at a 2-3C discharge rate.

Did somebody say 45/70? Oh, no, that was "old4570". Makes me feel younger. :)

Dave
 
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