Rechargeable Li-Ion Shelf Life

I did a search and couldn't find an answer to this question -

If you have some rechargeable Li-Ion batteries sitting around, being used only occasionally, and then recharged, but not being used very often, how long do you think they will last?

If you want them to last as long as possible, is it better not to use them at all? Or does it matter?

Hello LightScene,

You may find this thread informative...

Tom

It has been said that after two years, used or not used, that rechargeable li-ions will lose their capacity.

I haven't seen much long term testing, though.

People have said that they only have a certain percentage of capacity (probably 50% or so) after 5 or 6 years.

2-5 years, after that they won't hold a charge very well. As long as they're not abused, it doesn't make much difference whether they're sitting on a shelf or being charged every other day.

SilverFox said:

Hello LightScene,

You may find this thread informative...

Tom

Click to expand...

[From that thread: "On March 24, 2005 I charged an unprotected 18650 Li-Ion cell up to 4.000 volts and placed it in room temperature storage. A few hours later it was at 3.989 volts.

On March 26, 2005 it was at 3.976 volts.

On May 14, 2005 it was at 3.975 volts.

On October 1, 2005 it was at 3.974 volts.

On December 11, 2005 it was at 3.973 volts.

On February 10, 2006 it was at 3.973 volts.

On March 2, 2006 it was at 3.973 volts.

On April 19, 2006 it is at 3.973 volts.

Not much in the way of self discharge...

EDIT: I tested this cell for remaining capacity, then charged it back up to 4.000 volts and checked the capacity again. After 1 year of room temperature storage, this cell had 95% of its original capacity."]

So how is that 18650 cell doing now?

Lithium rechargeables have shelf life of around 3 years, regardless of use or not. After a certain period the electrolyte slowly 'eats up' the positive plate and the electrolyte decays. This chemical change causes the internal resistance to increase. In time, the cell resistance raises to a point where the battery can no longer deliver the energy, although it may still be retained in the battery.

Hello LightScene,

That particular cell got used up in various testing. I was checking out what happens when you charge to 4.3 volts instead of 4.2 volts. It cut the cycle life very short and basically ended the life of that cell.

I do have a sister cell that I charged to 4.100 volts 12/10/2005. I just checked it and it has self discharged all the way down to 4.076 volts.

I put it into my SureFire U2 and have all 6 levels, so it still is able to hold voltage under load.

This cell is part of a long term test that I am running. The cell is from an old laptop battery pack. It is rated at 1700 mAh, but the best I have been able to get from it under a 1 amp load is around 1100 mAh. However, it did charge up to just under 4.2 volts, and it holds voltage under load, so it seems to still be in reasonable condition.

I charged it to 4.100 volts a little over 3 years ago. The plan is to wait another 2 years, then to do a series of tests to see how well it has aged. Judging from the little "informal" testing under load that I just did, it seems to be holding up quite well.

Tom

I have been under the impression that li-ion has improved in recent years as far as shelf-life is concerned. The 3 year rule may be a bit premature. I have a couple if AW 17670s that I bought about 3 years ago that are still working pretty well. Lately I have been cycling them in my Argo HP. They are probably discharged and charged on average once every 2-3 weeks. I can't complain

Eric

The problem is not self-discharge, but degradation.

Li-ion degrades significantly over 2-5yrs when fully charged at room temp.

IF you store them at like 50% charge and/or put in the refrigerator (not freezer), the degradation is so low they'll outlive the product for sure.

Laptops are the worst. The elevated temps inside a running laptop degrade the batt several times faster than at like 72F. And people want them charged to 100% all the time so battery power will always be available. That's why many laptop batts are pretty dead by 2 yrs.

While there are a bunch of slightly different lithium technologies (lithium ion, lithium polymer, lithium nanophosphate) they're supposed to all be subject to very similar degradation problems. There's no cure for it.

Li-ion shelf life?

I've been reading that li-ion rechargeable a have a shelf life of 1 to 2 years. What happens at the end of that magic period? Anybody have any first hand experience they can share?

Re: Li-ion shelf life?

WilsonCQB1911 said:

I've been reading that li-ion rechargeable a have a shelf life of 1 to 2 years. What happens at the end of that magic period? Anybody have any first hand experience they can share?

Click to expand...

I think a little bit longer, say 3-5 years.

Lots of things will affect that number, like the temperature that they're used/stored in, how deep a discharge you go down to, before charging back up, how high you charge them up to, or not and the number of cycles.

You will start to see them lose capacity, or not charge up to the typical 4.20v level.

I had some Soshine 16340s that I got new from Orbtronics and one of them went 'critical' after a few months. It would start self-discharging after a few days and not charge up to my typical Xtar WP2 II's 4.18v, so I trashed it early. The other one is charging up to only 4.11+ volts after 15 months or moderate use, but that's still good enough for 20-30 minutes in a ShiningBeam I Mini.

Chris

Re: Li-ion shelf life?

WilsonCQB1911 said:

I've been reading that li-ion rechargeable a have a shelf life of 1 to 2 years. What happens at the end of that magic period? Anybody have any first hand experience they can share?

Click to expand...

That's mostly older info from the early days of consumer lithium ion products. The cell chemistries back then weren't quite as refined as they are today, and that caused them to have a finite life of around 2 years. What would happen around then is similar to how the infamously short lived energizer 2500 batteries were, they would self discharge rapidly and get very hot on recharging. It isn't a "fine one week gone the next" problem, they just slowly deteriorated as most batteries do and the 2 year mark is when the battery performance was bad enough to warrant replacing the product most of the time.

I have a set of first generation Bosch 10.8/12v max lithium ion tool batteries that are still going strong without those typical problems, they don't have quite the capacity reserve they did when new, but they're also over 5 years old now. Some of newest lithium cell chemistries have the potential (edit:well, "claim to have the potential") to live 20+ years.