18650, when to throw them out?

I recycled a bunch of 18650's from old laptops. What is the minimum voltage that I should read before I should attempt to recharge them?
A goggle search yielded different answers. Some say 2.4v, some say 3.4v.
At what point do I throw them out?

There's only one safe answer: if you need to ask this, then don't do it, old laptop cell's aren't worth the risk.

That said: anything above 3.0V is probably fine to have a go at (charging them & capacity tests etc). Down to ~2.5V probably too, but with smaller chance of success.

If the cells are at a lower voltage than that, and sat like that for weeks, months or longer: tread carefully, and probably better to discard them (if only for safety reasons).

In any case: below normal operating voltages (~3.0V for Li-ion), limit charge current to very low levels (like ~1/50C or less).

I have a few friends who give me laptop pulls for my lights I use around the house. If they come to me with lower than 2.5V, I throw them out. I've probably discarded 20% of all the cells I get because of low voltage. I also throw them out if they charge/test at under 2000mAH - probably another 10% have been tossed because of low capacity.

Amelia said:

I have a few friends who give me laptop pulls for my lights I use around the house. If they come to me with lower than 2.5V, I throw them out. I've probably discarded 20% of all the cells I get because of low voltage. I also throw them out if they charge/test at under 2000mAH - probably another 10% have been tossed because of low capacity.

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Can I test MAH with a volt meter?
If you've got the time, share your recycling routine. The basics that I should be checking with my meter, to insure that my laptop batteries are safe.

I've got about 30 of them that are reading 2.5volts, they were in storage for +2 years. Other posts suggest to toss out anything below 3.25volts.
And some suggest anything lower than 2.7 is unsafe. I dunno what I should do with my 30 batteries.

Thanks you two!

freman said:

Can I test MAH with a volt meter?
If you've got the time, share your recycling routine. The basics that I should be checking with my meter, to insure that my laptop batteries are safe.

I've got about 30 of them that are reading 2.5volts, they were in storage for +2 years. Other posts suggest to toss out anything below 3.25volts.
And some suggest anything lower than 2.7 is unsafe. I dunno what I should do with my 30 batteries.

Thanks you two!

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I've had very good success rate resurrecting cells around 2.5V, much lower and they often don't want to come back. It's worth a try.

mAH capacity can't be tested with a volt meter, you need a charger with test capability like the BT-C3400 or MH-9000.
As far as my "recycling routine", what I do is first is measure voltage and throw out anything under 2.5V. I then clean up the cells, often the laptop pulls my friends give me have glue or grout sort of paste on them from being in the laptop packs. I remove this, and any left over tape or labels. I clean them with paper towels and alcohol. The cells in laptop packs are usually welded together with metal strips, and when the cells are pulled away from the strips it leaves little metal weld burrs on the ends of the batteries. I get rid of these with fingernail sandpaper emery boards. A friend of mine told me a dremel would be faster, but I don't own one. After cleaning the cells, I'll charge, then discharge them 3 times, taking the mAH reading on the third charge cycle. If the capacity is under 2,000mAH, I figure the cell is pretty tired and I don't really want to mess with one that low a capacity anyway... those get discarded. After that, they're just like any other 18650 unprotected cell, I use them around the house in my extra Zebralights and Armytek Predators and Vikings, as all of those lights have under discharge protection that keeps the cells from going under 2.7V. I've occasionally used them in other lights without discharge protection, but I'm careful to not run them all the way down.

I hope this helps you!

+1 Amelia.
Nice post.

When you get them out and they read anything "Fire".

I recover 8 x Red label 18650 from a battery recycle box in my local supermarket, they only test to 1800-1900mah, but they work fine in my usb battery box.

John.

Amelia said:

After that, they're just like any other 18650 unprotected cell, I use them around the house in my extra Zebralights and Armytek Predators and Vikings, as all of those lights have under discharge protection that keeps the cells from going under 2.7V. I've occasionally used them in other lights without discharge protection, but I'm careful to not run them all the way down.

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Unknown cells, I wouldn't use them in devices that will draw more than 1C. Nor let them get below 3V.

Check out the tutorial on this forum. It has a good check list of steps to follow. It's by Craig of illumination supply.

Also be careful pulling the tabs off. I used to do this but now I just cut as much as possible and carefully file them down. The reason is that removing the spot weld can damage the casings. I've ripped some holes in some.

Mr Floppy said:

Unknown cells, I wouldn't use them in devices that will draw more than 1C. Nor let them get below 3V.

Check out the tutorial on this forum. It has a good check list of steps to follow. It's by Craig of illumination supply.

Also be careful pulling the tabs off. I used to do this but now I just cut as much as possible and carefully file them down. The reason is that removing the spot weld can damage the casings. I've ripped some holes in some.

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More great info.

Part may depend with some folks on how thrifty, they want to try and be.

Thank you +1, safety pays big time.

Str8stroke said:

When you get them out and they read anything "Fire".

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When you get them out and you see fire! :duck:

Amelia said:

I hope this helps you!

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It did, many thanks!

Just remember that many laptop pulls are already old and tired to begin with. While you can use them, you probably don't want to start throwing them into your new Noctigon M43 Meteor, or charging them up at 1C or greater.

I've got 8 2002 Sony 2000mAh cells from a pack and 4 LG 2000mAh cells from another (4 were dwanky, so tossed). I try not to put more than an amp, amp and a half on them and I charge them up at 500mAh, just to be safe.

They're good over time and still work, so they're spares, but not something that I'll bang on hard.

Chris

freman said:

I recycled a bunch of 18650's from old laptops. What is the minimum voltage that I should read before I should attempt to recharge them?
A goggle search yielded different answers. Some say 2.4v, some say 3.4v.
At what point do I throw them out?

Click to expand...

freman said:

Can I test MAH with a volt meter?
If you've got the time, share your recycling routine. The basics that I should be checking with my meter, to insure that my laptop batteries are safe.

I've got about 30 of them that are reading 2.5volts, they were in storage for +2 years. Other posts suggest to toss out anything below 3.25volts.
And some suggest anything lower than 2.7 is unsafe. I dunno what I should do with my 30 batteries.

Thanks you two!

Click to expand...

ChrisGarrett said:

Just remember that many laptop pulls are already old and tired to begin with. While you can use them, you probably don't want to start throwing them into your new Noctigon M43 Meteor, or charging them up at 1C or greater.

I've got 8 2002 Sony 2000mAh cells from a pack and 4 LG 2000mAh cells from another (4 were dwanky, so tossed). I try not to put more than an amp, amp and a half on them and I charge them up at 500mAh, just to be safe.

They're good over time and still work, so they're spares, but not something that I'll bang on hard.

Chris

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Yep pretty much this. Probably best just to retire them period but if you are looking for a few spares for low level usage otherwise i would prefer to recycle them when laptop cells will usually be no good when you get the laptop. I got 2 laptops, one of the battery packs were completely dead the other set were going bad, currently using the one laptop but the cells are pretty much toast in that laptop as well.

Great advice here, all, on the issues relating to using old laptop cells.

Indeed. I don't see anything posted that I'd consider "incorrect" or bad info.. but some of it is open to fudging by opinion. Example: I would disagree with RetroTechie that laptop pulls are not worth the risk/hassle. I think many times they are if you are looking for unprotected cells. Yes, there are dangers. Accidental shorting of the battery pack while disassembling is a very real danger. I've come close myself with a few sparks off of the circuit board.

But after tearing apart a little more than half a dozen laptop batteries, I have 42 fully functional, unprotected 18650's with 2000+mAh capacity. All LG, Sony, or Panasonic cells. I also have new, protected 3100mAh Panny's I've purchased, but that's different. The laptop pulled cells work great in all of my single cell lights (which is all but one).

That being said: I have had about an 80-85% success rate with those. The ones that come back up to voltage and have decent capacity were all at 2.7 ish volts or higher. I've recovered some as low as 2.3, 2.4 or so. But that was rare and maybe a bit lucky.

So to answer the original query, I would toss cells that no longer charge, heat up excessively during charge/discharge, lose their voltage in storage over a short period of time, drop below 60% of original capacity, or have physical damage beyond torn wrappers. But that's just me.

Slow charge + slow drain = more rechargeable longevity. I'm aware of no chemistry that's otherwise at this time.

Anyone know of the new hotness? I'm all ears.

I have some 10-year old 18650s that still run well even given reduced runtime. Processed lots of laptop batteries to get a few dozen cells.

Dremell tool is your friend.

JasonJ said:

Example: I would disagree with RetroTechie that laptop pulls are not worth the risk/hassle.

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Misread: my point was that if you attempt to recover old laptop pulls etc, you have to know what you're doing, understand potential risks, and proceed accordingly. Then it's fine. For example I have a 6-pack 18650's that I pulled from a new-old-stock battery pack found on clearance. Perfect material for a tinkerer like me! Old, fully drained, probably sat like that on a shelf for a long time. Yet recovered to a large degree, all in regular use now.

But to someone who has to ask what's safe to do, "just have a go at it" is bad advice & may end in disaster. If it's likely the cells will recover, go for it. If unclear, but relatively safe to try: sure why not. But it's just not wise to advise a 'newbie' to step into "know what you're doing" territory, if it appears they don't fully understand possible risks. Again: if not the case, they wouldn't be asking these questions.

I would toss cells that no longer charge, heat up excessively during charge/discharge, lose their voltage in storage over a short period of time, drop below 60% of original capacity, or have physical damage beyond torn wrappers. But that's just me.

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I toss cells that -given their condition- I can't find a useful purpose for any more. No hard limits. If I can find a suitable use, it stays. If not (and can't think of a future application I'd use that cell for), it goes.

etc said:

Dremell tool is your friend.

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My Dremel friend is nearby...

RetroTechie said:

my point was that if you attempt to recover old laptop pulls etc, you have to know what you're doing, understand potential risks, and proceed accordingly. Then it's fine

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This. Also, know the ones to let go. Let go your crappy system pulls, charge them outside with a super smart charger than can tell you current capacity on a charge/disharge cycle.

This is the way of the Force!

lovecpf