# Can Lithium be brought back to life?



## sailfish11 (Sep 15, 2007)

My charger stopped charging over the winter and I didn't notice it in time. Now my 98 Thundersky TS-LFP60AHA cells are dead. I didn't check all the cells, but some are at .03V, some at .01.

Am I totally screwed or is there some safe way to bring them back to life?


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## frodus (Apr 12, 2008)

If they're under 1V, they're probably goners.... but it may be possible if it was a very slow discharge.

Do you have a single cell charger? an adjustable power supply?


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## rwaudio (May 22, 2008)

sailfish11 said:


> My charger stopped charging over the winter and I didn't notice it in time. Now my 98 Thundersky TS-LFP60AHA cells are dead. I didn't check all the cells, but some are at .03V, some at .01.
> 
> Am I totally screwed or is there some safe way to bring them back to life?


some people have had luck bringing cells back as long as they weren't driven into reversal. I've brought back a hand full of A123 20ah cells that I abused in testing and discharged to 0.1v they came back with slightly reduced capacity and maybe a bit higher IR. Charge them slowly at first and ideally individually as some of them may come back and some may not.
Good luck.


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## major (Apr 4, 2008)

rwaudio said:


> some people have had luck bringing cells back as long as they weren't driven into reversal.


I have had pretty good luck with LiPoly cells. Some down to essentially zero. They didn't seem to lose capacity. Can't speculate about cycle life on the recovered cells. I just charged up to 3.4 volts one cell at a time, in a LiPo sack (just in case). Not a particular slow charge, maybe C/2, with a power supply. If they hold that charge for a few days, then they're worth using. A few wouldn't take any charge, or self discharge overnight. Those are junk. It takes a lot of time and effort, but worth it in my case.

I can't tell you if it'll work for LiFePO4, but I'd give it a shot. I wouldn't mess around with cells which are distorted or leaking.

major


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## EVfun (Mar 14, 2010)

If all the cells are between 0.01 and 0.03 volts aren't they in a state of maximum bottom balance?


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## sailfish11 (Sep 15, 2007)

Thanks for all the responses.

Ok, so if I try to bring them back, it sounds like a need a single cell charger and a LiPo sack -- anyone have a recommendation for the charger? And what is a LiPo sack? I'm guessing it's to contain the cell while charging in case of fire. Any links to recommendations for either would be appreciated!

Looks like I've found my Spring project.....


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## major (Apr 4, 2008)

sailfish11 said:


> Thanks for all the responses.
> 
> Ok, so if I try to bring them back, it sounds like a need a single cell charger and a LiPo sack -- anyone have a recommendation for the charger? And what is a LiPo sack? I'm guessing it's to contain the cell while charging in case of fire. Any links to recommendations for either would be appreciated!
> 
> Looks like I've found my Spring project.....


http://www.liposack.com/ Just in case


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## mora (Nov 11, 2009)

I had 30 cells at 0.1V or less. 90Ah Thundersky cells. 23 of them came back to life and still have lower internal resistance than newer Winston cells. Capacity seems to have dropped a bit (can get barely 90Ah at 1C) but otherwise those are performing good.

I wired four of them in series and slapped 12V lead acid charger to the terminals. I watched them closely and disconnected charger when cell voltages were at 3V. If any cell started heating up I disconnected charger and put warm cells aside. None of them got hot but some were warm to touch. Cells that didn't hold charge at all were abandoned. Some cells lost charge overnight. Those were abandoned too. All the "failed" cells read 0.00V. Ones that read 0.01V survived.


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## batterytang (Nov 17, 2011)

Oh, bad luck, here are some useful suggestions.

It is a litter dangerous to recover the LiFePO4 batteries which volt is very low like 0.01 V or so.

If the voltage of LiFePO4 cell is under than 2.0V, that means the balancing of li-ion status have been broken, and the SEI (solid electrolyte interface) film was damaged.

To recover it means to rebuild the SEI film and re-balancing the li-ion status of LiFePO4 battery.

You may charge every single cell with a very very small current (like C/200 or even small), it can slowly rebuild the SEI film, while you need to keep watching on battery from time to time, especially for thurmal generation.This step would generate a lot of thermal to re-build SEI film, so you should keep fan cooling else it may even cause fire..

Keep a small charging until the volt is higher than 3.1V (or at least 2.5V), then you can charge it as nominal CC/CV charging method, also with that single cell charger. After that you may do several charge /discharge cycle, to see whether battery is OK now. 

The most important step is re-building SEI film process, it should be watched very careful especially for thermal generation.


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## sailfish11 (Sep 15, 2007)

Thanks again everyone. Anyone have suggestions for a good single cell charger?


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## sailfish11 (Sep 15, 2007)

I've been searching EV parts suppliers and haven't found any single cell chargers. I've found some that seem designed for RV'ers, but nothing that seems made for my purpose. Any help would be greatly appreciated!


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## frodus (Apr 12, 2008)

http://www.batteryspace.com/smartchargerforlifepo4batterypacks.aspx


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## sailfish11 (Sep 15, 2007)

Awesome -- thank you VERY much!


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## batterytang (Nov 17, 2011)

you may take a look at this

http://stores.headway-headquarters.com/-strse-110/3.65V-10A-CHARGER/Detail.bok?category=CHARGERS


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## sailfish11 (Sep 15, 2007)

Thanks, but I'm thinking lower amperage is better for my purpose, right? Better off with a small .7 amp charger than a 10 amp one?


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## batterytang (Nov 17, 2011)

Hi sailfish,

0.7A charger is good, but it is a little hard to find it... 

How about finding a battery maintenance shop for cell repairing?

As I mentioned before, repairing LiFePO4 cell is somehow trouble some. If you have a number of cells need to be repaired, I suggest you to find a battery repairing workshop to do that. They can adjust the volt and current for single cell, then recover cell and do cycle test etc.

Single cell charger is mainly used for particular applications like testing, balancing, or necessary steps before battery pack assembly. 

P.S.: My English is not so well, I am a Chinese young gay..

P.S.: A 3A charger for your reference.
http://www.batteryspace.com/smartch...k1cellstandardfemaletamiyaplug38vcut-off.aspx


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## boekel (Nov 10, 2010)

What about the Cellpro Powerlab 6 (or 8)
http://www.revolectrix.com/pl6_description_tab.htm

I've bought a bunch of 20Ah cells and use it to charge and test them, you can also do automated test cycles.
You can charge 6 cell's at the same time with it and program any voltage / amps.


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## sailfish11 (Sep 15, 2007)

boekel said:


> What about the Cellpro Powerlab 6 (or 8)
> http://www.revolectrix.com/pl6_description_tab.htm


That's a nice one -- but I think it's overkill for what I need. I bought two simple 3a chargers that were $24 each.

What about charging three cells at a time on each charger (in parallel). Would that work (it would certainly speed things up), or should I stick to one cell at a time?


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## boekel (Nov 10, 2010)

sailfish11 said:


> That's a nice one -- but I think it's overkill for what I need. I bought two simple 3a chargers that were $24 each.


I have to disagree with that, looking at cell-cost, if you can raise two of them from dead you're winning.
Also you can cycle them and get accurate results of improvement.


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## sailfish11 (Sep 15, 2007)

I spent several hours today bent over my car disconnecting and pulling out all 98 cells. I set them out on the garage floor and tested each one. They ranged from zero (only one of them), to 1.3 V. Average was about .9 V.

I numbered the cells 1 through 98 and set up spreadsheet to track each one. It will interesting to see how many come back -- if any.

I ordered the chargers and they should come in this week. Then the experiment begins.


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## sailfish11 (Sep 15, 2007)

The chargers finally arrived Wed, and Thurs I had some time to start charging. I ordered two 3A chargers to try to cut down on the time this whole process is going to take.

So far I've attempted to charge eight cells. Seven seemed to take the charge, one didn't. The seven 'good' ones had starting voltages in the range of .3 to 1.3V. The one that didn't had a starting voltage of .4V.

I charged the seven up to around 2.8 to 3V, then let them settle. It took about an hour at 3A to get them up to that.

I'm away for the weekend, so they're just sitting there in my garage until I get back. When I get back tomorrow I'll check the seven, and start charging some new ones.

The one that didn't take a charge just sat there when the charger was hooked up -- the voltage didn't go up or down. The charger's led flashed green (which is not one of the indicators mentioned in the user's manual -- it's supposed to be solid red when charging and solid green when finished. Flashing isn't covered...).

Assuming the seven are able hold their charge over the weekend, then (so far at least) that's not too bad a recovery rate.

Here's to hoping....

One other thing, one of the chargers has stopped working. Hopefully the place I bought it from will stand behind it and ship out a new one. I've also just bought some wire and alligator clips to use to daisy-chain 3 cells in parallel to speed up the charging process a bit more more. That should also bring the batteries back slower (1A each) which I'm thinking is probably a good thing.


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## sailfish11 (Sep 15, 2007)

For what it's worth -- it took less than 10 min to get them up to 2.5V, then it really leveled out and the charge went up much more slowly from 2.5 to 3V.


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## sailfish11 (Sep 15, 2007)

I'm halfway through. After charging 50 batteries up to approx 2.5V, 46 charged normally and seem to be holding their charge - so only 4 bad cells so far. Much better than I thought it would be.

The four dead cells had starting voltages of 0, .011,.169, and. 058.

The lowest starting voltage that I've managed to save is. 429. There have also been several between. 429 and 1.0 that seem to be ok.

My plan is to get through all 98 cells, charging them all up to 2.5V. Then I'll order replacements for the bad cells, and go through the pack again, charging up to 3V while I wait for the replacements to arrive.

Still early, but so far I'm happy.


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## Coulomb (Apr 22, 2009)

sailfish11 said:


> The one that didn't take a charge just sat there when the charger was hooked up -- the voltage didn't go up or down. The charger's led flashed green (which is not one of the indicators mentioned in the user's manual -- it's supposed to be solid red when charging and solid green when finished. Flashing isn't covered...).


It's possible that the charger considered this one to be so far out of spec that it's not safe to charge, or the short circuit protection cut in, or something like that.

It might be possible to resurrect even these cells, if you can get the process started somehow. It might be as simple as inserting (in series with the cell) a one ohm resistor (any value from about 0.2 to 10 ohms should work). That will make the cell not appear such a short circuit, so the charger might be able to put some current into it. Once the voltage reaches say 2.0 V or higher, remove the resistor and continue charging normally. The resistor will get hot, so make it at least a 5 W resistor.

Failing that, a bench power supply might be able to get them started, or you could use another cell with the resistor in series to force some current into the cell. Make sure that you have some resistance in series, as there is a distinct possibility that the bad cells actually are short circuited, or nearly so.


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## sailfish11 (Sep 15, 2007)

Coulomb said:


> It's possible that the charger considered this one to be so far out of spec that it's not safe to charge, or the short circuit protection cut in, or something like that.


That's possible, but I have two chargers and only one did the flashing green light thing -- and now it does that no matter what battery I hook it up to, so I'm thinking the charger's gone bad. I'm returning it to the shop.

The other charger is working -- although it won't charge the four bad cells either. The three that were below .1 won't even charge at all; the one that was at .169 takes a charge, but won't hold it.


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## sailfish11 (Sep 15, 2007)

I've finished my first round of charging. I attempted to bring all the cells up to around 2.7V, then checked to see how well they held the charge. At first, there were 8 cells that had their voltages drop significantly. Three of them dropped to near zero and were clearly dead. The other five dropped to around 1.5V and seemed to stay around there, so I gave them all another round of charging. After charging those five up to around 2.7V again, three of them held the charge.

So after round 1, it seems I've only lost a total of five cells. All five had initial voltages of below .2 (.011, .169, .058, 0, and .155). There was one cell with a starting voltage below .2 that I was able to save (.175); the rest all had starting voltages above .3.

So,
> .3V = 100% save rate
.1 - .3 = 33% save rate
< .1 = 0% save rate

I've placed an order to replace the five, and I'm beginning round 2 of my charging, to bring them each individually up to 3V. Then I'll put them back in the car and finish the charging as a pack.


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## jumpjack (Sep 9, 2012)

I had similar experience with 16 40AH Thundersky LFP cells.
One of them reached 0.006 volt and I wasn't able to recharge it higher than 0.050V, but all the others quickly raised from 0.40-0.50 to 2.50, and then I was able to het them to 3.20 in an hour... using a Lead charger, but also using a BMS connected to the whole pack.
I still have to check how much of the original capacity is still available.



mora said:


> I had 30 cells at 0.1V or less. 90Ah Thundersky cells. 23 of them came back to life and still have lower internal resistance than newer Winston cells.


Which is the IR of a brand new Winston cell? Can't find this data in datahseet.


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## mora (Nov 11, 2009)

Sorry, I have no definitive answer for that. I didn't measure all the Winstons I have when I first got them, but those I measured seemed to be over 1.0 mOhm. Old TS cells ranged from 0.8 to 2.5 mOhm while most of them are close to 1.0 mOhm. I've replaced all the cells with IR over 2.5 mOhm as they became weaker and weaker in traction pack way faster than others. More IR, more heat inside the cell = early cell failure. High IR cells will be fine for other purposes where amp draw is low.

I'm surprised that old TS cells can still have IR lower than 1.0 mOhm even if they went down to 0.1V resting voltage.


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