Rechargeable Lithium Battery Long Term Viability

We've seen a decade or so of usability, but only if properly stored.

That basically means stored at not too low nor too high of a voltage, and under cool temperature conditions. If you are uncomfortable, so are they. The cells you are using are used, and of course the typical go/nogo factor is if they won't hold 80% of their rated capacity - recycle and replace.

On this forum we've gone into great lengths about the "perfect" voltages to store at, storing in a fridge in a ziplock baggie, allowing them to come up to room temp before opening the baggie and subsequently recharging etc etc.

But if one is seeking long-term storage at the most perfect voltage, if a prepper-incident, happens <grin>, then that cell may not have enough capacity to do anything useful.

So a compromise is reached between perfect storage conditions, and having more available capacity when it is truly needed.

For us, that would be about 60-80% charge capacity when stored as the compromise. We've got plenty of nifty chargers that we can test cell capacity first, and then make measurements as to how long to get into this range.

But what do we tell our neighbors who think we are kind of weird anyway? Watch as eyes glass over when you get into it..

Many neighbors right now are maintaining lawns and using other li-ion tools to do stuff in the summer. But what about wintertime when these tools are put away? Give or have them buy an Xtar or similar? Nice but not realistic.

So just simplify it greatly. Tell them to recharge their tools to full. Then when charge is finished, have them pull the trigger or whatever mechanism it is to just spin for a minute or two. This is simply to get the charge away from the top end before storage. Then, simply advise them to not leave the battery hanging in the garage - take it inside - just to minimize the heat issue. The addage "if you are uncomfortable, so are they".

Applies to cell-phone / usb charger packs too. If they only use it on vacation, and don't plan on using it very often, charge to full, and then take it off the top by charging something up one time - or just a little bit. They'll still have enough left in a REAL emergency.

That's about as much as they can take. Get the cells off the very top, and keep them cool before the next building / maintaining season begins. Keep it super simple.

But yeah, for us it is a different story with all our nifty measuring tools. Perhaps buy new cells, validate their capacity and performance, and store at the perfect voltage (representing about 30-40% capacity), and keep an eye on them as time passes.

I have 8 Sony ~2000mAh that are date coded 2002, that I scavenged from a Sony VAIO laptop pack my brother bought new sometime around '03/'04.

They are still good for ~1500mAh and 1.5A. I charge them up at 500mA just to be safe and they relegated to backup/SHTF duties.

Chris

Good name-brand cells are a lot more resilient than is often claimed. I have old Samsung 22F laptop cells that are over 10 years old. They still measure about 80% of their capacity with a discharge test. Still good for a few amps output, though they were never high-discharge cells to begin with.

They were almost always in the laptop at 100% charge. The last 2 or 3 years, the laptop wasn't used, so they discharged slowly. I think they were around 3.6v when I pulled them.

I think proper storage (cool conditions, at a voltage around 3.7v), should allow good 18650's to last at least 10 years. I wouldn't be surprised to get to 20 years under ideal conditions, and still have usable cells.

The only thing I think will contribute is when storing for a long time, try to store them above 2.5v but around 50% capacity. They don't like to be stored at or near full charge.
Most battery spec sheets and I admit not to having read any in a couple years ask to store at 50% or 2.65 to 2.7 volts depending on the battery.

How long can a 16650/18650 battery be stored unattended?

Ie if set to the 3.8v storage charge, could I leave them for 2-3 years in my families vacation home without them dying / reducing storage capacity significantly?

dspencer said:

The only thing I think will contribute is when storing for a long time, try to store them above 2.5v but around 50% capacity. They don't like to be stored at or near full charge.
Most battery spec sheets and I admit not to having read any in a couple years ask to store at 50% or 2.65 to 2.7 volts depending on the battery.

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No, 3.7v is about 50% charged. If you store them at 2.7v (which is basically empty) you're asking for problems.

spyderco monkey said:

How long can a 16650/18650 battery be stored unattended?

Ie if set to the 3.8v storage charge, could I leave them for 2-3 years in my families vacation home without them dying / reducing storage capacity significantly?

Click to expand...

As long as they're not in a device that drains them (even very slowly), they should be fine. Charge them up again before using, and they will have lost very little capacity. Preferably keep them in a cool place.

WalkIntoTheLight said:

As long as they're not in a device that drains them (even very slowly), they should be fine. Charge them up again before using, and they will have lost very little capacity. Preferably keep them in a cool place.

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Thank you. I figure year round storage temp will average ~80-90 degrees in the vacation house. All the AC and refrigerators are unplugged when we're away, and its in a part of the world thats pretty hot.

Not wise. If you are uncomfortable at 80-90F, so are the batteries, no matter the level of charge if you want the longest life from them.

Also, being unattended at a vacation house is not wise either - heaven forbid there is a fire - even if not caused by the batteries, but something else, if the batteries in turn catch on fire and start another flash point - things can go bad in a hurry.

Not just from an insurance standpoint blaming the batteries, but obviously the health and welfare of the neighbors.

Basically - for a vacation house - just take some batteries with you.

IonicBond said:

Also, being unattended at a vacation house is not wise either - heaven forbid there is a fire - even if not caused by the batteries, but something else, if the batteries in turn catch on fire and start another flash point - things can go bad in a hurry.

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While that may be true, if a fire starts when nobody's there, it's going to burn down the house whether or not it ignites some batteries. So, I think it's a moot point. Also, I've never heard of lithium-ion batteries spontaneously catching fire when they're idle and not installed in something. They catch fire when charging or discharging, or being abused somehow. Just keep the batteries in a plastic case when storing them, and stick with genuine name-brand cells.

IonicBond said:

Not wise. If you are uncomfortable at 80-90F, so are the batteries, no matter the level of charge if you want the longest life from them.

Not just from an insurance standpoint blaming the batteries, but obviously the health and welfare of the neighbors.

Basically - for a vacation house - just take some batteries with you.

Click to expand...

I'm actually pretty comfortable at 80-90 degrees; thats become a nice summer day living in an area that spends months at 105-115f.

Ideally I'd like to avoid spending the next 10 years flying back and forth with a bunch of 18650 batteries.

Hmm, I've left batteries stored in my car (both in cases and in lights) year round (-30 to +30 C).
Lights always work when I go to use them. Maybe not ideal storage, but it's too much of a hassle to bring them in an out each time as I need to have my gear always available.

This is a follow-up to my initial test, to demonstrate how well the batteries did/did not hold charge.

Thanks for the effort!

Just a few comments:

Get a decent digital multi-meter if you're going to be playing with batteries and chargers.

You can Goggle 'date codes for lithium ion 18650s' and look for Battery Bros.

Those look like my Sony 18650s, which are ~2000mAh cells and date coded 2002 harvested from Sony VAIO packs.

Next, state of charge tells us very little about the health of a cell. You need to do a discharge test on an analyzing charger to get a handle on true capacity and preferably at something close to matching the load of the device you intend to use them in. At least at 1A.

Chris

ChrisGarrett said:

Thanks for the effort!

Just a few comments:

Get a decent digital multi-meter if you're going to be playing with batteries and chargers.

You can Goggle 'date codes for lithium ion 18650s' and look for Battery Bros.

Those look like my Sony 18650s, which are ~2000mAh cells and date coded 2002 harvested from Sony VAIO packs.

Next, state of charge tells us very little about the health of a cell. You need to do a discharge test on an analyzing charger to get a handle on true capacity and preferably at something close to matching the load of the device you intend to use them in. At least at 1A.

Chris

Click to expand...

Thank-you. What is the cheapest charger that is user-proof as possible that you would recommend to me?

N/Apower said:

Thank-you. What is the cheapest charger that is user-proof as possible that you would recommend to me?

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I'm going to assume your abilities are above the average 'village idiot,' so look for the Opus BT-3100 v. 3.1, or Litokala Lii 500 Engineer...both analyzing multi-chem chargers that do discharge tests.

I've got the Opus 3100 v. 2.2, which discharges down to 2.8v vs. 3.1v for v. 3.1.

Chris

WalkIntoTheLight said:

While that may be true, if a fire starts when nobody's there, it's going to burn down the house whether or not it ignites some batteries. So, I think it's a moot point. Also, I've never heard of lithium-ion batteries spontaneously catching fire when they're idle and not installed in something. They catch fire when charging or discharging, or being abused somehow. Just keep the batteries in a plastic case when storing them, and stick with genuine name-brand cells.

Click to expand...

I keep mine in an air tight metal ammo can, also protected from touching the inside of the can/insulated. If they do catch, my goal is containment.