Advice on reviving LiNMCo cells.

V

varntzberg

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Hello good folks!

I was wondering if any battery wiz out there have tried to revive LiNMCo cells. Any experience, advice etc is very welcome!

The situation is as follows:

I have managed to get hold of a shitload of 75 Ah, good quality Dow Kokam cells for free.

24s6p
About 40kWh worth to be exact.. :D

Datasheet: http://www.xaltenergy.com/images/pdfs/datasheets/XE_Data_75HP.pdf

The only problem is (of course), that someone made a cockup of epic proportions, and as such managed to completely deplete the cells.

I'm talking sub 0.01V...

The cells were practically new and only had a few cycles on them, if any at all.

I have tried bulk-charging 8 cells today at sub 1/20 c, and for now at least the cells seem to be holding charge. I stopped @~3,4V out of respect for my life..

Am I an utter shitlord for even attempting this?
Would it be worth it to revive them (if possible), or am I either way sitting on a metric buttload of lithium waiting to dendrite-selfdestruct?

It's a great modular system, and I even have the BMS for them. Love the thought of all the projects I could do with this, but I'm really sceptical due to the amount of energy involved.

Hopefully I posted this in the right place! If not, please let me know.

Regards
varntzberg
 
Pics!

Internet rule #23 = take pics, or...it didn't happen.

Let them rest at the current voltage (3.4V per cell), and after a week or so, measure the state of charge (SOC) and see if any have drifted down, or if they are holding steady. Are they flat square foil-packs? (prismatic?). If yes, compression on the sides will lower resistance.
 
Get them to 3.0v+ slowly and let them sit as SM suggested to see if they retain voltage... Usually, if they got drained at a very low discharge rate ( like a greedy BMS , or an unplugged charger on the AC side ) they tend to survive.

For this procedure, make sure the cells/packs are placed in an area where you have nothing to loose if the worst case scenario was to happen :wink:
 
Well, you got a good deal on those.

I agree if you charge them at a low rate, usually C/20 until they get above 3.0-3.1v or so then charge at the normal rate, you can test them. It may be worth building or buying a capacity tester for discharging.
 
I had my 3s lighting pack of EIG NMC 20Ah cells totally drained to zero once while parked at work, and was able to slow-charge it, and it appears to have suffered little from that incident. At least 3 years later I'm still using it; I don't know for sure it's capacity now as I charge after each use to ensure I always have enough, and I don't know if it's C-rate or internal resistance was affected, as it's not used at even 1/3C. :)

But if yours is the same chemistry, and they were not drained down at high C-rates, they could well recover fine.


Still...I charged mine up the first time under a bucket outside, just in case. ;)

(since then I haven't worried about it...if it didn't happen then, it probably never will).
 
A while back I drained my wife's 6 old Fatpacks with older Sony VT's to zero. I trickle charged them up to about 3 volts and then put them back on the standard charger. They seem to have recovered and are still in service now. This was 120 cells and they are still working as a power pack for her trike motor // with a 10 AH Ping. The Ping is over 4 years old and still working.
otherDoc
 
i think it is the rate of gas formation at the electrode interface which is the determining factor.

so low discharge rates are recoverable but high discharge below the 2-2.4V level where there is no available lithium ions to transport current can cause gas formation at a rate sufficient to damage the electrode/electrolyte interface.

i have now done the same with nimh cells in my honda hybrids batteries. discharged at low rates to 0V and then recharged to higher capacity than before the reconditioning. something i had never thought possible before this.
 
I was able to revive some 40Ah Kokams I salvaged from a large pack where the BMS and other factor had pretty much completely drained them. It was a few years ago, but I think I saved about half. Aside from obvious bloating and refusal to accept a charge, if the cell becomes limp, it is bad. Good cells are pretty stiff. If it feels soft and flexible, toss it. I was told to soak bad cells in salt water for a few days and then to the garbage dumpster. I've had revived cells test to full capacity and cycle well. I've lost a few, but they died quietly.
 
i like the salt water bath for discharging to discard. if there is any voltage left in the cell it will create the hydrogen gas and it foams up in the bucket. you know they are dead when the hydrogen formation ceases.
 
Then It's settled! I shall try to revive them!

Well at least some.. 153 cell's is a bit stiff, but hey! Maby I'll figure out the ultimate technique for reviving LiNMC!

Or should I just go apeshit, and save all the packs? At ~6,6kWh each, ~110kW peak discharge and 24s they have to be usable for some projects right..?

Any project-ideas are also plenty welcome!

Snowmobile?

Small boat, with ludacris power2weight ratio?

Gocart?

Snow-blower?


Thank you all for the great advice! I might even try to keep the thread updated if I make any progress =)



@999zip999: 75Ah @3.7V (check the datasheet in the original post) also I live in Norway.

@spinningmagnets: True dat.. Unfortunately I'm on a work trip atm, but I'll post some pics of the pending shenanigans when I get back høum!



Regards
varntzberg
 
999zip999 said:
My brother lives in Harstad. I can download it, but my phone won't let me read it ??? So 75ah 3.6v normal ?
Click to expand...

Awright, Trondheim here.

Nope. Nominal would as pr usual be 3.7v.

"
Performance Characteristics Typical
Capacity (Rated @ C/2) 75 Ah
Voltage (Nominal) 3.7V
Discharge Energy (C/2) 278 Wh
Weight 1.75 kg
Specific Energy 159 Wh/kg
Volumetric Energy density* 360 Wh/L
DC Resistance (10 s @ 50% SOC) 0.71 mΩ
Peak Power 4.9 kW
Specific Power 2800 W/kg
Volumetric Power Density* 6200 W/L
*Volume includes core cell dimensions excluding tabs
Cycle Life Typical
100% DOD Cycles @ 1C charge-discharge >4000 cycles*
80% DOD Cycles @ 1C charge-discharge >8000 cycles*
*Cycle life to 80% of rated capacity
Operational Range Typical
Upper Voltage Limit 4.2V
Lower Voltage Limit 2.7V
Charge Temperature Range 0°C ~ 45°C
Discharge Temperature Range -20°C ~ 60°C"

Regards
varntzberg
 
varntzberg said:
Then It's settled! I shall try to revive them!

Well at least some.. 153 cell's is a bit stiff, but hey! Maby I'll figure out the ultimate technique for reviving LiNMC!

Or should I just go apeshit, and save all the packs? At ~6,6kWh each, ~110kW peak discharge and 24s they have to be usable for some projects right..?
Click to expand...
If you decide not to revive them, I'd be curious what it might cost to get some of the likely-revivable ones (those without physical issues) from you to me, here in Phoenix, AZ...I will always need large-capacity batteries, and my bikes are large enough to carry packs made with cells that large. :)
 
I had opened many laptop batteries, kept the good cells and set the 0v's aside. I found that paralleling them for about a minute with a good cell would jump some of them right up to 3-3.5v, most would sit there and then work well and some would slowly drain back down. Haven't done any tests on the recovered one's but I think it is just because they sat for so long and the ions or whatever just became inactive until they received a small jump start. Not at all saying it is a good thing to do but no fires or nothing for the year or so they have been sitting.
 
For ye who doubted :p

Currently working on building a more potent charger.. 24V 121A, so that this wont take foreeevar..

Have tried one cell tho, it somewhat holds charge.. Force it gently up a couple of times, and for each time the voltage stabilizes at a higher level.
1st test cell currently holding @ 3,8V

S20150424_144244.jpg
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1415891425155.jpg
Bananananana.jpg
chrg.jpg
 
if all of your cells are of the same origin and have been charged together for this period then it would be best to charge them all together instead of charging one at a time so you should just allow the BMS to balance the pack and use the bulk charger you buy for the pack. if you use a single cell charger they will all be so far outa balance it will take the BMS forever to balance the pack.

your charger looks more like a discharger it is nothing but resistors in the pictures.
 
True dat, however this is to attempt to revive the cells using high current for a shorter period of time. Also I have charged some groups in bulk, and the cells came out VERY unbalanced. Wierd shit apparently happens when lithium goes 0.004V The resistors are for disch. Just a mock up to provide 30A through a psu.
 
the problem with pushing high currents into a discharged cell is that there is nothing inside the cell to conduct the current when the cell is discharged below 2.5V.

there are no free ions to use to carry the current in the cell so all a high current can do to a totally discharged cell is make heat just like your resistor.

so high current charging from low voltage is just about the only way to make it worse.
 
dnmun said:
the problem with pushing high currents into a discharged cell is that there is nothing inside the cell to conduct the current when the cell is discharged below 2.5V.

there are no free ions to use to carry the current in the cell so all a high current can do to a totally discharged cell is make heat just like your resistor.

so high current charging from low voltage is just about the only way to make it worse.
Click to expand...

Naturally. I bring them up to >3V first @<1\20C. Batteries are 75Ah, so charging after they have stabilized takes waaaaay to long :)
 
ok, i will repeat. you do not wanna charge up each cell individually. use the bulk charger and BMS to charge the battery up.

if you have charged them up to 3V then connect them all in parallel and charge them all up in parallel if you only have a single cell charger.

but once they are balanced by connecting in parallel then you can put them into the pack and charge and balance them with the bulk charger and BMS.
 
dnmun said:
ok, i will repeat. you do not wanna charge up each cell individually. use the bulk charger and BMS to charge the battery up.

if you have charged them up to 3V then connect them all in parallel and charge them all up in parallel if you only have a single cell charger.

but once they are balanced by connecting in parallel then you can put them into the pack and charge and balance them with the bulk charger and BMS.
Click to expand...

As will I: I have allready bulked them. they differ. Yes BMS could handle that at lower currents, but it would take freakin ages. And that is if I could get a hold of a 100,8V cc/cv supply for cheap. What I have done, and what I can confirm works, is to gradually "cycle" them higher, whilst carefully monitoring the temperature, until they no longer self discharge @ 4,2V. Letting them rest between cycles, has prooven effective.

So in short: I charge while monitoring. When calometric efficiency goes to shit, I rest them and let them self discharge to where ever they end up. Point here, is that they always go higher than the previous cycle. Unless ofc I let them get too hot. Then hindenburg.

Trial and error bruh. And I still have 143 out of 152 subjects left.
 
Man-o-man... how does one position ones' self to come across such an incredible freebie??
 
varntzberg said:
dnmun said:
ok, i will repeat. you do not wanna charge up each cell individually. use the bulk charger and BMS to charge the battery up.

if you have charged them up to 3V then connect them all in parallel and charge them all up in parallel if you only have a single cell charger.

but once they are balanced by connecting in parallel then you can put them into the pack and charge and balance them with the bulk charger and BMS.
Click to expand...

As will I: I have allready bulked them. they differ. Yes BMS could handle that at lower currents, but it would take freakin ages. And that is if I could get a hold of a 100,8V cc/cv supply for cheap. What I have done, and what I can confirm works, is to gradually "cycle" them higher, whilst carefully monitoring the temperature, until they no longer self discharge @ 4,2V. Letting them rest between cycles, has prooven effective.

So in short: I charge while monitoring. When calometric efficiency goes to shit, I rest them and let them self discharge to where ever they end up. Point here, is that they always go higher than the previous cycle. Unless ofc I let them get too hot. Then hindenburg.

Trial and error bruh. And I still have 143 out of 152 subjects left.
Click to expand...

i am trying to help you since you know nothing about batteries. the BMS does not limit the charging rate unless you have a small BMS which you will not if you are using these cells. you can charge at 50A with no problems using the D131 and charge at 100A if you use two of them.

what does calorimetry have to do with anything? you do not have to find a 100.8V charger. you can use a power supply in series with a charger to regulate the charging current through the power supply to get to 24S lipo. i use 101V as the final voltage for 24S lipo to balance.
 
dnmun said:
varntzberg said:
dnmun said:
ok, i will repeat. you do not wanna charge up each cell individually. use the bulk charger and BMS to charge the battery up.

if you have charged them up to 3V then connect them all in parallel and charge them all up in parallel if you only have a single cell charger.

but once they are balanced by connecting in parallel then you can put them into the pack and charge and balance them with the bulk charger and BMS.
Click to expand...

As will I: I have allready bulked them. they differ. Yes BMS could handle that at lower currents, but it would take freakin ages. And that is if I could get a hold of a 100,8V cc/cv supply for cheap. What I have done, and what I can confirm works, is to gradually "cycle" them higher, whilst carefully monitoring the temperature, until they no longer self discharge @ 4,2V. Letting them rest between cycles, has prooven effective.

So in short: I charge while monitoring. When calometric efficiency goes to shit, I rest them and let them self discharge to where ever they end up. Point here, is that they always go higher than the previous cycle. Unless ofc I let them get too hot. Then hindenburg.

Trial and error bruh. And I still have 143 out of 152 subjects left.
Click to expand...

i am trying to help you since you know nothing about batteries. the BMS does not limit the charging rate unless you have a small BMS which you will not if you are using these cells. you can charge at 50A with no problems using the D131 and charge at 100A if you use two of them.

what does calorimetry have to do with anything? you do not have to find a 100.8V charger. you can use a power supply in series with a charger to regulate the charging current through the power supply to get to 24S lipo. i use 101V as the final voltage for 24S lipo to balance.
Click to expand...

Oh lawdy, the pretentiousness in your last comment is quite frankly astounding.

I'm starting to doubt you even read the first post. So let me try to get your attention for more than the last few lines of text.

So you may understand the issue_

If you have the capacity.

>>I am trying to revive the cells.
>>Problem is that as cell voltage rises, it comes to a point where the energy I supply the battery with, no longer is charging the cell and only contributes to heat.
>>Hence "calometric efficiency gone to shit".
>>Counter this by resting the batteries when dV/dt = 0 @ CC
>>Your setup with charging on a lipo balancer is cute, but I must remind you that the cells are 75Ah.
>>And the point at where they stop taking charge and develope heat instead, differ ENORMOUSLY.
>>This happens quickly.
>>I cannot leave whilst charging which would mean that I'll see you sometime next year using your method.
>>Which still does not work.
>> doing 6 cells at the time at higher current, will let me more easily monitor both temp and individual dV/dt

/endrant

Because of the huge difference in SOC the batteries take before they start heating up, I do not dare not to monitor them individually (temp wise).
Besides, I prefer to do it small scale on a smaller batch at the time, until I find a process that is suitable.

Therefore 24V 121A

Also the level at which they stabilize afterwards differ hugely, so either way they end up insanely unbalanced.
Whiiich in turn means that it does not take long before some cells kill charge current because 4,2V and some r still ded.

I would love to bulk/bms charge them, but it's not suitable. Some cells might survive, but it's simply not suitable, I know, I tried.

/endrant v2.0

Now as for autistic bickering on forums, for the sole purpose of bickering; count me out.

General advice on reviving dead lithium (on a cell-level) is much appreciated!

Lastly: I appreciate your help but implying anyone knows nothing on a subject, simply because they disagree is rather counter productive.


Tl;dr

What CC/CV charger I use is irrelevant, unless it can monitor dV/dt + temp and kill charging on individual cells.


*Edit: parts of my post probably came across as more rude than I intended :oops: . Sorry bout' that. Hot-tempered + internet = bad combination :p . *
 
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