# How do you charge up unprotected 18650 cells from 0V?



## wshyang (Aug 7, 2012)

Hi all,


The reason why I am asking is... because I do have quite a bunch of them that are at 0V from laptop salvages. Reading around some old posts, it seems like in *some* cases it can be boosted back to life, so I figured maybe I should give it a shot!


Have you done it before? How did you go about it?


What I've read included things like:


1) hooking up the battery to a current generator set to a very low 50ma.
2) connecting the battery in parallel to a good battery, and slowly "jolt" it back to a more recoverable voltage using quick pulses.
3) by using a hobby charger, charge it up using the NiMh mode that ignores the low voltage cutoff
4) Apparently the Xtar SP2 seems able to do it too, but at 0.7ma (not even 1ma) I reckon it is going to take days just to wake a cell up, so perhaps I can do it faster


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## czAtlantis (Aug 7, 2012)

0V meas the cell is really dead! You shouldn't charge them because they are not safe anymore and can develop internal shortcuts (at low voltages some copper chucnks form and can shortcircuit the cell). I charged myself many cells from laptop salvages at around 1.5V and I just connected to my lab power supply with 50mA current limit and let it charge up to 3.5V. After that I proceeded as usual and cycled the cell few times with my iCharger. All cells are fine and recovered to 95-100% nominal capacity.

If you really want to do this, let me clear the procedures you listed:
1) Probabaly good idea but you have to monitor the voltage.
2) Very bad idea! Current flow will be huge and you can destroy the cell!
3) Good idea but again - you have to monitor voltage and once it reaches 3V set it to liion mode
4) 0.7mA it way too low if your cell is discharged so much.

EDIT: I rebember i tried to restore cells from laptop pack discharged really to 0V like yours and I had very low success rate. Many cells had huge selfdicharge, some of them couldn't be charged at all (significantly heating up during the charge). From 8cells I restored 3 of them and their capacity was around 40% nominal. Two of them failed in very short time and only one cell survived until now (I have it somewhere here). Really bad success ratio...


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## AnAppleSnail (Aug 7, 2012)

Cells that have sat at 0V have actually had internal parts do exciting things like wander off from where they should be. In some cases, at low voltage the copper terminal is soluble in the electrolyte solution below about 1.5v, so you really cannot charge these cells. In all cases, cells at low or high voltage undergo oxidation or reduction to quickly reduce their capacity. That's not "increased self-discharge," it's just flatly reduced capacity. Also these can catch on fire and poison you horribly. Please buy real cells!


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## 45/70 (Aug 7, 2012)

Unlike NICd/NiMH cells, there is no such thing as restoring, refreshing, or bringing back a Li-Ion cell. Once they are damaged, have lost perofromance, or do not hold a charge well, they cannot be restored.

As for recovered cells extracted from laptop battery packs and such, generally the only ones that are any good are those that were harvested from the pack because the laptop died before the battery pack, or the pack was an extra one that still worked. Once one cell in a battery pack goes bad, the others are not far behind.

As for bringing up the voltage of a Li-Ion cell so that it can be charged on a charger, this can be done, but there is a good chance that the cell has already been damaged, particularly if the cell voltage has been allowed to drop below 1.5 Volt. Cells that have been allowed to sit at voltages above 1.5 Volt for a length of time, may also have been damaged. This depends on at what voltage and for how long the cell was stored in this condition.

In general, cells that are pulls from battery packs that have been allowed to sit at low voltages, are not worth attempting to charge. The chances of obtaining a useable cell are minimal, and has been mentioned, there is also a chance of a "vent with flame" incident occurring when attempting to charge recovered cells with a low voltage. Copper shunts can form across the separator within the cell causing a direct short, and when charging current is applied to the cell, the cell's internal components can heat up and thermal runaway can occur. Note this can happen very quickly and without warning, eg, a temperature sensor on the cell may not catch the situation in time. This is a direct short internally, not just simply an overheating condition.

My advice is to dispose of/recycle any cell that reads 1.5 volt OC, or less. Cells in the "gray area" of 1.5-~2.5 Volts OC may be OK, but again, it depends on how long the cell has been at a low voltage. Cells that have been stored at voltages in this range have likely been damaged to some degree, but may be safe to use. They may exhibit less than optimum performance however. It would also be a good idea to keep a close eye on such cells for a while, watching for excessive heating during charging and discharging. If the cells heat up, dispose of/recycle.

Dave


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## czAtlantis (Aug 7, 2012)

In my experience cells around 1.5V (stupid electronics, it slowly discharges them) can be charged just fine. I extracted cells from 4 laptop battery packs (new ones but old stock sold with significant discount in our PC shop). They are Panasonic (different models) cells and after slow charge they have really 95-100% nominal capacity and work just fine. And I believe they were at this voltage level for a long periods of time (year+).
But really 0V is really dead and I wouldn't try to restore them...only as "project" but really don't use them


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## 45/70 (Aug 7, 2012)

czAtlantis said:


> In my experience cells around 1.5V (stupid electronics, it slowly discharges them) can be charged just fine. I extracted cells from 4 laptop battery packs (new ones but old stock......



Hi cz. I don't think new/old stock cells are a fair comparison to cells extracted from battery packs where one or more cells have already failed, from which many are obtaining their cells.

Like the 24 hours of Le Mans, new cars are less susceptible to failure than those that have many miles on them at the start. Things that seem to be OK will start to fail. Similarly, cells extracted from "used" battery packs have suffered at least some degradation of the separator, due to normal use. New/old stock cells, depending on their age, may have suffered little degradation and will stand a much better chance when allowed to drop to a low OC voltage. Just saying......

Dave


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## wshyang (Aug 8, 2012)

Wow, reading all these stern warnings posted, I suppose it is a really bad idea...! 

I've managed to befriend an local exporter of old laptops and he agreed to sell me old laptop batteries for a buck or so each, much cheaper than I can otherwise get them from eBay at, so I guess I don't need to be so hardup about getting every last cell to work now! I'll give it a shot and document it as I go along for other CPFers who might like to go this path to get their cheap 18650 fix


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## AnAppleSnail (Aug 8, 2012)

wshyang said:


> Wow, reading all these stern warnings posted, I suppose it is a really bad idea...!
> 
> I've managed to befriend an local exporter of old laptops and he agreed to sell me old laptop batteries for a buck or so each, much cheaper than I can otherwise get them from eBay at, so I guess I don't need to be so hardup about getting every last cell to work now! I'll give it a shot and document it as I go along for other CPFers who might like to go this path to get their cheap 18650 fix



"How do I charge questionable cells?"

"At a distance." Do be sure to use a quality charger. You could probably make charging leads to protect your charger. Use rare-earth magnets soldered to wires and put alligator clips on the other end. This will let you charge questionable cells in a fire-resistant box (Look up 'LiPoSack,' they're one product) to protect you, your fingers, lungs, and skin, and your charger.

Note: You'll get crummy capacity and current delivery out of old cells. Unless you're making a ton of project lights, it's probably worth about $10 per AW 18650 plus shipping. That will give you reliable performance and far fewer house fires.


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## billw (Aug 8, 2012)

In my experience, the average "dead" laptop battery pack will have a couple cells that read zero volts (and are responsible for the pack being "dead"), and a rather larger number that still read 3 to 4.2V and may be of "reasonable" quality. I haven't actually measured such cells' capacity and remaining life, but I think they might be worth experimenting with (Carefully!) Keep in mind that Li-ion cells are supposed to have a maximum lifetime (in years, not charge cycles), and all the cells in a pack will date from the same manufacturing timeframe. I have cells that were removed from "dead" packs that have sat around on shelves for a couple of years, and they're still reading 4V. (how many WH they can deliver is a separate question, of course.)


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## HotWire (Aug 9, 2012)

Early on I tried to revive dead cells and found (1) most do not recover, and (2) Even if they appear to accept a charge they don't last long before needing additional charging. I've not personally had any explode, but I did my charging outside on a cement patio. I don't do it any more. Dead is dead. Buy some AW, Redilast, or Calllie's Kustom cells and you'll be glad you did. Safety first.


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## willieschmidt (Aug 9, 2012)

Made a hobby of harvesting laptop cells in the last year. Follow a few simple rules. 1. Use cells from packs less than 3 years old. 2. Identify cells and their capacity. Stick with Panasonic, Sanyo, Samsung, Sony, etc….quality cells. 3. Check voltage of individual cells. Discard any that read below 3.2v. 4. Use a hobby charger to determine capacity. Discard any cells that are less than 80% capacity. Label capacity. Discard any cells that gets extremely warm or hotter than usual. This applies to ANY LI-ION cell regardless of source or protection circuit. 5. For multiple cell flashlights use matched cells from the same pack with same capacity

The tips I give about newer than three year old cells or packs that show alot of wear on the outside are not concrete. Good cells can be found in any pack but my luck as been better with newer pack and higher capacity cells. If you have 2 packs by all means test them all. But if you luck into 8 or more you can be selective as it takes time to go through 48-72 cells. My best cells to date have been 2600ma+. 



Disclaimer: If you are uncertain about anything written above then don’t. YMMV


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## CMAG (Aug 9, 2012)

I have three words for you. (+ all of the above)

Lipo Charging Bag


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## iron potato (Aug 10, 2012)

I once had an old, unprotected blue wrapper TrustFire 18650 parasitic ​drained by UltraFire UF-H3b.

Took out & leave it for around an hour, still couldn't climb back to above 3 volts.

I 'jolt' back by using your no.2 method, leave around 20-30 seconds or so in my Apex 5T6 battery tube (which runs parallel)

Upon taking it out, it was a little warm, measured 3.43v, let it cool down to room temperature.

Charge in my SP2 @ 1A, still working & I remember to lockout instead of press off after every use now.


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## bob_ninja (Aug 25, 2012)

I am using many cells from old laptop packs. I simply charged them and supervised, kept an eye on charge process. Then I left them idle for several weeks while checking voltage. Bad cells drop below 4V, so easy to identify, no risk. Remaining good cells are serving me well. I sometimes check them while charging. They are mostly cold and bit warm towards end of charge.
So with some reasonable precautions cells can be recovered and used safely.


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## POMANFERRARI (Nov 30, 2012)

bob_ninja said:


> I am using many cells from old laptop packs. I simply charged them and supervised, kept an eye on charge process. Then I left them idle for several weeks while checking voltage. Bad cells drop below 4V, so easy to identify, no risk. Remaining good cells are serving me well. I sometimes check them while charging. They are mostly cold and bit warm towards end of charge.
> So with some reasonable precautions cells can be recovered and used safely.



I got 8 CGR18650A cells from a Dell laptop that had been sitting for 8 years uncharged. 4 of the cells read 2.81V and 4 reads 1.68V. Throw away the 1.68V cells?


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## LilKevin715 (Dec 1, 2012)

POMANFERRARI said:


> I got 8 CGR18650A cells from a Dell laptop that had been sitting for 8 years uncharged. 4 of the cells read 2.81V and 4 reads 1.68V. Throw away the 1.68V cells?



I'd advise to throw them all out...


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## kostyak_pl (Jun 5, 2013)

Hi Guys! 

I dissasembled my dead asus battery. Two cell are bad, but rest four seems ok

I have two ICR18650 2400mah by samsung @ 1,5V which i want to ressurect.

Charging with 50mA right? But what about charging voltage? Start from lower or stay within normal 4,2V ? 

Greetings from rainy :/ Poland


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## Bumble (Jun 5, 2013)

with the price of good 18650 cells from reputable sellers nowadays, i simply cannot see why people engage in trying to "make good a damaged li-ion"... 1.5v for how long ? in any case the cell will have been damaged. be safe and recycle would be my advice... before you might end up with a trip to a hospital.


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