18650 lowest you have restored.

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afkane
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18650 lowest you have restored.

Guides say anything under 2 volts to toss in the Trash and theres videos of people saying cells above 1 volt can be charged back up. I have 2 cells at 1.76v each. If I were to take them outside and charge them for a little bit while constsntly checking the temperature to make sure it doesnt get warm. Can this work or should I just toss them in the trash now.

jmpaul320
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you could try

but I would just err on the side of caution and purchase a few new cells and recycle the old ones

risk a fire/explosion? samsung 30qs were on sale at gearbest for $3 each last I checked

you might be fine but personally I wouldn’t want to risk anything

Would you mind keeping the wrong flashlight?
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Ronin42
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I had a new NCR18650 PF that taught me that a particular light had parasitic drain.

in other words the light ran it dead just sitting. it read somthing like .9v or maybe .6 I mean it was dead.

so on to the charger at low charge.

it seems that it is back with no ill affects (checked the Irr still very good) capasity just fine.

OR

try it what have you got to loose?

(I know it is a bit of a baiting phrase) but if approached carefully determine if and how much damaged has been caused.

And yes if it gets “hot”!… bail and toss it. but if you can “test” it (some chargers do this) then why not find out what kind of capasity it has?

But yes be carful in the future using this cell in series, maybe this becomes a tool box or dayily carry (somewhere where lots of cycles but not record setting current drains might be a good home for it.

(“It’s good that most people can’t remember their previous lives. Otherwise
things would be a lot more complicated than they already are.”
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will34
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I have a Nitecore HC50 with very high self discharge and several times I have measured unprotected LG E1 4.35v cells below 1V after leaving them in there for few weeks. Charged them back to 4.35v just fine and measured capacity with my Opus shows practically no loss (3120mAh). Of course the charger refused to take the cell so I “jumped” them with another low draw 3.0V cell by short bursts. Using fully charged high drain here would probably have make them explode.

Cells did not get hot at all when charging and it didn’t took longer than usual. CC/CV cycles and termination time were normal, and internal resistance was on par with my other good cells.

I don’t know how safe or how unsafe that is but personally speaking I wouldn’t throw otherwise good cells away just because voltage measures less than 2V. However I do advice to test them with the right equipment for capacity and IR before using them again.

DBSAR
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its risky regardless, but i have brought back a few cells from the dead with 1 volt left in them, and they recovered fully with not bad internal resistance and still have good capacity testing. I have has others though that did not, they either tested with a very high IR or lost half their capacity and got to warm on charging. Safety precautions must be taken, and charge at a very low current to revive them. (in a fire proof container, outside, etc.
Its up to you if you want to try to revive them, but keep the risks in mind when first attempting it.

That Canadian flashlight guy & Lantern Guru -Den / DBSARlight

blueb8llz
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jmpaul320 wrote:
you could try

but I would just err on the side of caution and purchase a few new cells and recycle the old ones

risk a fire/explosion? samsung 30qs were on sale at gearbest for $3 each last I checked

you might be fine but personally I wouldn’t want to risk anything

That’s dam cheap. Did you get any? You know if they are authentic?

dchomak
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Just recently I “revived” some cells from a NOS laptop pack I found in the recycle bin. The cells were sitting at 1.80V and I charged them up. They were Panasonics and they looked so pretty. Smile Originally rated at 2200mAh, at a 1A draw in the OPUS, they tested out at 1850mAh. The problem was that 30 minutes later they “recovered” to 3.70v. Not a good sign.
What was even worse was that each successive test gave lower and lower mAh ratings meaning that these cells were deteriorating fast. I recycled them.

I have also performed this test with IMR cells from drill packs. They are not harmed as much, but nonetheless I would stay away from over discharged cells for safety sake.

Milan
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0, zero, flat, Panasonics

bmwsancho
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I revived a 1.1V 18650 Oege cell earlier this year, it came back with the help of my VC4 charger and still does the job. It was a brand new cell and was stored in a warehouse at the wrong charge.

blueb8llz wrote:

That’s dam cheap. Did you get any? You know if they are authentic?

Generally speaking the GearBest lithiums are authentic. Have bought a few from them and they are all good, exact capacity match and also charge/discharge rates.
Pulsar13
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0.6V Sony from laptop, charged back fully to 4.2V, left fully charged for a week and voltage maintains.

HOWEVER, leaving that battery unused for about 8 months – the voltage drops to 3.6V.

So there’s already an internal leak, very minor – absolutely undetectable with normal capacity testing and short term rest test.

So you just can’t be sure when reviving dead batteries. Up to you to weigh the risk.

mongoose
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Pulsar13 wrote:
0.6V Sony from laptop, charged back fully to 4.2V, left fully charged for a week and voltage maintains.

HOWEVER, leaving that battery unused for about 8 months – the voltage drops to 3.6V.

So there’s already an internal leak, very minor – absolutely undetectable with normal capacity testing and short term rest test.

So you just can’t be sure when reviving dead batteries. Up to you to weigh the risk.


How would it be ‘leaking’? What is the process allowing it to happen?

homer

Emma
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you can try

Running like a man!

hank
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Quote:
should I just toss them in the trash now.

No, because you don’t want to risk being responsible for starting a toxic waste fire in the trash dump, do you?

What’s available where you live to take care of it?

afkane
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hank wrote:
Quote:
should I just toss them in the trash now.

No, because you don’t want to risk being responsible for starting a toxic waste fire in the trash dump, do you?

What’s available where you live to take care of it?

Oh by that I meant taking them to interstate battery for recycling that I have 2 blocks away.

Boaz
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mongoose wrote:
Pulsar13 wrote:
0.6V Sony from laptop, charged back fully to 4.2V, left fully charged for a week and voltage maintains.

HOWEVER, leaving that battery unused for about 8 months – the voltage drops to 3.6V.

So there’s already an internal leak, very minor – absolutely undetectable with normal capacity testing and short term rest test.

So you just can’t be sure when reviving dead batteries. Up to you to weigh the risk.


How would it be ‘leaking’? What is the process allowing it to happen?
Even i know this one …. It’s called a short . Where is the voltage going? I’m guessing the flow is only going one place , from pos.+ to neg.- .

Self duscharge is happening in all battereies all the time. At room temp. Nicads lose 20%
Nimh 30% ..lead acid 5% li-ion 10% li-po 10%, alkaline 0.3% depends also on state of vharge , temperature etc.

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You know what really sucks? Typing a post only to find after hitting save that the forum requires you to log in again and deleted the post. Angry Rather than re-typing my entire post again I’ll just say after a rather complex process I successfully restored four sanyo ncr18650ga at around 1.78v to normal functionality. Ir increased a bit but a stepped charging process – .3a ,5a, .7a seems to be successful. According to my lii-500 ir is in the 40 mR range.

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wle
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you can usually get them going down to .9V or so, but it is dangerous
the theory is that the cell has been damaged, and it may charge and work for a while but there may be a short or near-short
later, the short may become worse and start fire, explosion, that sort of thing
i’ve restarted 16340s that were very low ( a trick is to connect them directly to another battery in parallel for a couple seconds, the volts briefly rise, slap it in the charger on low current)
but my theory is that these are small and weak and hopefully would not cause huge problems
18650s, i have thrown out at 2V, because i have tons of them and they are more dangerous
(i don;t want to buy new 16340s since they all seem to suck)

your mileage may vary

wle

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WalkIntoTheLight
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Samsung 30Q spec sheet says not to recharge if below 1.0v. Between 1.0v and 3.0v, charge slowly until it reaches 3.0v, then charge at the normal rate.

So, I’d definitely be wary of any cell that is sitting below 1.0v.

OTOH, I’ve seen a study that states a cell doesn’t form those dangerous dendrites until it is significantly reverse-charged, something like 12% reverse charged IIRC. That is, it’s down to 0v, then you continue to reverse charge it by putting in 12% of the mAh of the battery. It’s polarity is flipped.

I think that sounds very dangerous, and I don’t think the tests let it sit at those levels for very long. Personally, if a cell has been reverse-charged, I’d throw it out. Just for lithium-ion, of course, I have successfully restored NiMH cells that show reversed polarity.

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Does it also depend on how long the battery has been sitting at the low voltage?

For instance, I’ve restored a few 18650s that went below 2.0v (I forgot how low, but they were probably sitting at more than 1.5v), after doing the slow charge, and then a few more regular charge/discharge cycles, they seem to be back to nearly normal (I’m not sure how much battery capacity they lost, but probably not that significant, if ever).

In one case, the battery was probably below 2.0v for less than 1 day (flashlight became defective and had high parasitic drain that caused the battery to be drained to below 2.0v, but it was about only for 1 day). In another battery, I think it’s several days or a few weeks, but after restoring, they seem to work. I don’t use the restored battery in high drain flashlights, but using in the stock Convoy S2+ or Convoy C8, they seem to work normally after restoration.