Would you use this cells?

K

Klommer

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Nov 16, 2017
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Hey all,

yould you use cells that has been discharged arround 2,2 -> 2,5V?

They are Panasonic NCR18650A build in those packs and where discharges over ~ 2 years of an attached bms.


image_spzrrk.jpg



Regards


Carsten
 
Of course. 90% of my cells have been below that before they got in use and no problem.

I dont care of initial voltage as such more than lower ones could potentially yield in lower capacity results.
 
Absolutely, 2.2V to 2.5V isn't that low actually, they don't even need a special treatment to get going again. Just charge them up und they are ready to go!
 
Okay, but where do you put your border? 1,5V? 1,0V? Or would you measure the capacity and decide on this parameter?


Regards


Carsten
 
The border is where a cell doesn't take a charge or has poor capacity after charging or it gets hot each time it's charged or the cell reads 0V and has no continuity. Even a 0V cell can be revived
 
Ok ill see what they are able to bring. Sounds like no body if afraid of getting a thermal runaway or do you all put the trust into the cells CID?
 
For cells with very low voltage (for me I choose this to be <2 v), I charge at 70 - 100 mA until they reach at least 3v. If they reach 3v, I finish off charging them at 250 - 500 mA to 4.2v. For me this is just a recovery charge to get them going ok. I fully discharge (for me this means 3v), then recharge before I do a capacity test.

As I'm writing this, I have 2 cells charging that read under 200 milivolts. They are taking the charge just fine.
 
No thermal runaway as long as you charge them slowly and just keep track of the temperature. I only threat cells below 1v with special needs. All others are dealt with the opus chargers since they start slow charging at 1v.
 
It is not easy to reach a thermal runaway, even if you deliberately try to do it. This is nothing which happens just so. Seems like you are concerned about it though. Any particular reason?
 
Mhh just because im just starting with the diy-power-wall and my wife just little afraid about our house. The wall shall be installed in our garage and i just want to minimize the risk. Therefore i ask this questions.

anyway i think this questions got asked many times and i still got to read more here.

btw: how to add new cells to the cell-DB? I got some Panasonic NCR18650PF, Panasonic NCR18650BD and LG INR18650MH1
that are not listed there
 
I think realistically you need to be more concerned about shorting out a cell when you are salvaging it. Because the negative shell is so close to the positive terminal, the nickel strip can slice through the wrapper and contact both at the time. I've had this happen a couple of times.

Once was fairly scary as it happened when the laptop pack was still 60% unopened. I still don't know what happened, but in less than a second one cell super-heated, melted through the battery pack AND the glove I was wearing. Left me a nice charred burn on my palm. Adrenaline helped me get that pack ripped apart and all cells separated in about 5 seconds so I could find and break the short. Even so, that cell and 2 others heated enough to blow their seals and leak.

Those cells now sit on my bench as a reminder to take my time and pay attention.

Charging/discharging I've had a few get hot, but nothing even close to the short.

Eric
 
Yep no problem with those cells at all.
Even manufacturers often list a revive current in their spec sheets. Usually its around 100mA until the cells reaches about 3V.

What where those packs from? Thats a lot of great cells in one pack :)
 
These are excellent cells. Even at 2V, I would try reviving them, as having 3000mAh cells at max would still be super duper.
 
I got them from my work, they where used to dev a modular bms for a HV application for a solar inverter ^^

But that project was chanceled by the leadership due to high risk because of dependencys from the cell manufacturer
 
Klommer said:
I got them from my work, they where used to dev a modular bms for a HV application for a solar inverter ^^

But that project was chanceled by the leadership due to high risk because of dependencys from the cell manufacturer
Click to expand...

Nice, whats their configuration, looks like you could just use it as is. Maybe just revive the whole pack and be done with it :)
how many did you manage to get?
 
I will get them out of this pack because i also got some other packs with NCR18650PF

In the blocks they are 14S5P but ill go on something different. not sure what ill use, 7s or 14s. not decided this yet

also not sure on what pip i shall go
 
If you havent decided go 14s. You already got packs premade :)
 
Y maybe ill do this but one problem for me is that the pip is using then much more stdby power then the 24V pip. I dont have the option to go to a 10->15kWh system due to limted space to compensate this. My solar ist only 5,6kWp and i got already an inverter. So my battery shall become an AC-couppled one with my PV and then effiency is what counts to me :)

Btw: did someone recorded some effiencycurves of the pip inverters?
 
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