LiIon 18650 - internal drain?

[KurtS]

What is the internal voltage leakage rate for an 18650 cell?
That is, what is the shelf life for a charged cell?
Does this vary much between cells - i.e. does a 2100 leak less than a 3400ah? or is it more by brand?

Thanks!

 

[Bumble]

Hi, "internal voltage leakage" by this do you mean the self-discharge rate of the cell ? what can effect this is the voltage of the cell at which its stored at, age of the cell, amount of charge-discharge cycles, and the temperature its stored at. li-ion like to be nice and cool and be stored around 3.7 volts ( there nominal voltage). as far as i know the mah of the battery doesnt make much difference to the self-discharge rates (its more the chemistry of the cell/ temp it stored at/ resting voltage of the cell and age of the cell that decides self-discharge rates)...but as cells get worn out, not only does the capacity decline but also the self discharge rate goes up (normally anyway).

EDIT from memory the average shelf life of a li-ion is around 3- 5 years of age. and is mainly governed by use/storage conditions/temp stored at. all these factors are going to effect the capacity/self-discharge of the cells.

 

[KurtS]

Sorry, I couldn't remember the correct term.
So, if I charge a quality 18650 and let it sit in a flashlight (stored at room temperature) with minimal use, after a month is most of the capacity going to be there?
I saw AW's storage graph (from http://www.cpfmarketplace.com/mp/showthread.php?230876-AW-s-LiIon-Batteries-Sales-Thread-*Part-12*) and see the energy really drops at higher temps.

 

[SilverFox]

Hello KurtS,

I just "found" a light that I had "lost" about a hear ago. It runs on 1 18650 cell. I stored it at 4.1 volts and after a year it was at 4.09 volts.

Tom

 

[KurtS]

Thanks! That's really helpful - says it's basically a non-issue.

 

[markr6]

Hello KurtS,

I just "found" a light that I had "lost" about a hear ago. It runs on 1 18650 cell. I stored it at 4.1 volts and after a year it was at 4.09 volts.

Tom

Nice! I thought it would be much less. Good to know!

 

[jasonck08]

Quality Li-ion's discharge very very slowly. Much more slowly than even LSD Ni-mh cells like Eneloops. I have some cells that for the sake of experimenting I put in my drawer in a zip lock bag. It's been 3 years this month.

Sanyo based protected cell is at 4.05v.
Panasonic based protected cell is at about 4.10v.

One thing you have to consider is if you are storing the battery in a flashlight, depending on the type of switch (mechanical or electronic switch) there would be some parasitic drain, that will cause the cell to discharge much more quickly.