Is there a safe way to use this 10-year-old 18650?

Brangdon

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I just bought a new 18650 torch, and a new battery to go with it. I also have an old battery that was bought for a Surefire U2 back in 2005, from Lighthound. It is a protected 2200mAh. This was flat. It's been sitting on a shelf, virtually untouched, for 10 years. (The U2 has Cr123s.) I forget what voltage it held, but it was under 0.5v. Rather naively, I put it in a (also new) charger, along with the new battery. After a few hours, neither charger light showed green, but I took them out anyway and tested them. The old battery showed 4v, now dropped to 3.97.

So, now what? It looks and measures fine, but I gather there may be internal damage. Is there any way to find out? I suspect if I put it in the torch it would work, but it might also make a pipe bomb.
 

ven

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Tbh i would just recycle it, not worth it and the V is at 70-80% at best..........and thats now!
 

archimedes

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:caution: That cell already shows multiple points of failure and multiple risk factors ....

* overage cell, with many years under improper conditions

* protection circuit has failed to keep voltage above 2.50 V

* cell has overdischarged, and remained in this state for an (unknown but presumably extended) period of time

* should never have been recharged, but did not reach normal termination voltage

* should never have been recharged, but does not maintain voltage, despite no load
 

Brangdon

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Thanks, but... how were the conditions improper? It wasn't connected to anything, just sitting on a shelf. How could the protection circuit make any difference? And isn't it normal for a cell to drop voltage slightly for a few minutes after being taken off charge?
 

archimedes

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What was the resting storage voltage ?

What is the voltage now, after no use for an extended duration ?
 
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SilverFox

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Hello Brangdon,

Charge it up under close supervision. When the charge indicates full charge, remove the cell and measure its voltage.

Next, let the cell rest for 24 hours and then measure the voltage again. If it is above 4.0 volts, use it. If it is below 4.0 volts, recycle it.

Tom
 

Brangdon

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The voltage now is 3.91. So it's dropped a bit since 3.97, but it's in the 100ths of a volt and room temperature is probably colder this morning. I had to fish it out of my recycling bag to measure that.

How long should it take to reach full charge from there? My charger is a Cytac CY-U10D, which uses 1000 mAh.
 
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