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Are there any chance that enough could be recovered to make a usable pack? Sinopoly 200ah cells
 

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Are there any chance that enough could be recovered to make a usable pack? Sinopoly 200ah cells
I am trying to restore my 3.2v LiFePO4 260ah prismatic winston cells and I was told 3.2v at .1c charge rate should be ok, but i'm wondering if even less current would work.

i feel like the chemistry can be "coaxed" back into being at a reasonable lifespan/capacity (ie not that much damage to cell) with very low current, and an incremental "push pull" type charging where you trickle a little current in, then drain it out, trickle a little more in at slightly higher voltage, drain, rinse and repeat till its full. This would be very cumbersome and time consuming but might help save the cells because the damage IMO occurs when trying to charge it from dead, the slow act of it going dead doesnt damage it as much.
https://www.diyelectriccar.com/forums/showthread.php/charging-30-kwh-dead-lifepo4-pack-200207.html
 

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It would be good to see your results, but I decided against taking the risk on been lumbered with having to dispose of them should they be knackered.
 

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Say if coddled, the bank could have lived 4000 cycles before dropping to 70% capacity, EoL recycling time.

And now after being resuscitated, capacity is already at 40%, and you only get 50-100 cycles before it drops to 30%.

Plus **much** higher risk of "unexpected sudden failure events" beyond the ability of the TMS to cope with. BOOM bad!

Wanna give it a go? No worries, but please don't join my kids' carpool. . .
 

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My experience with a CALB pack (very similar to winston) is that you may be able to charge them to normal voltage but the ones that truly hit bottom (in my case there was a mix) will now self-discharge at varying rates.

At the very least that means your pack will be constantly getting out of balance. I think there's also some risk over time of a spontaneous runaway event with any one of those cells.

My cells that had any measurable significant self-discharge were drained back to zero and taken to the recycler. Unfortunately that was almost half the pack and now I'm running a Volt pack.
 

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wow thanks for all the replies despite the foreboding results I might expect. Thanks a lot guys! (no really I appreciate it!)

The battery was made with 0v wasnt it? How does a slow discharge to 0v damage it so irreversibly? Doesnt make sense and adds credence to my theory that most people are charging them wrong from 0v.

anywhere I can get some more tech info on charging dead batteries? I have a feeling using a method like mentioned above I can get a better result.
 

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wow thanks for all the replies despite the foreboding results I might expect. Thanks a lot guys! (no really I appreciate it!)

The battery was made with 0v wasnt it? How does a slow discharge to 0v damage it so irreversibly? Doesnt make sense and adds credence to my theory that most people are charging them wrong from 0v.
Unfortunately there's lots of testing and research out there that says otherwise.
One (of many):
https://download.atlantis-press.com/article/25846169.pdf
"The over-discharge has a huge impact on the utilizable capacity and cycle life of the batteries. In particular, overdischarge may completely damage the battery when the battery voltage drops to 0 V, but the battery does not
ignite, explode or smoke. "
 

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Actually when learning about LFP batts, one of the first level 101 things you learn is

don't let them go dead flat, likely to become irreversibly instant scrap.

Going below 3.0V on a regular basis is stupid and risky, even if no obvious damage done you're killing longevity.

Most mfg spec is 2.5V, but just like the 3.6V max, it's a "don't even think about" outer limit.

Personally I go to extreme length to ensure staying above 3.1V even in an emergency, and LVCs start cutting big or nonessential circuits at 3.15

Allowing 0V you might as well take an axe to them
 

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Unfortunately there's lots of testing and research out there that says otherwise.
One (of many):
https://download.atlantis-press.com/article/25846169.pdf
"The over-discharge has a huge impact on the utilizable capacity and cycle life of the batteries. In particular, overdischarge may completely damage the battery when the battery voltage drops to 0 V, but the battery does not
ignite, explode or smoke. "
They likely tested these batteries with devices to quickly drain the current to 0v. this is a slow discharge to 0v, so I still have hope.


An over-discharge experiment with the 200 Ah
LiFePO4 power battery pack was performed by a threephase asynchronous motor load on the experimental
platform. Batteries #10 through #13 were damaged (the
battery terminal voltage was 0 V), the terminal voltage of
batteries #14 and #15 was approximately 2.71 V, and the
other battery voltages were between 3.08 V to 3.26 V. All
battery voltages are shown in Table 2.
An over-discharge experiment..... [performed] with threephase asynchronous motor load...

well a 3 phase asynchronous motor load on batteries sounds pretty sudden and intense. therefore that study has really no relation to my issue but thanks for sharing anyway it was a very good article.
 

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At a high rate just leave for a short time and you will see V bounce back, showing the difference between SoC and Voltage.

But then zero SoC is 2.5V, and 3.0V is in practice functionally equivalent, and lots healthier.

When load testing, the protocol is to not allow the cell to sit at 0% SoC / 3.0V for long, get at least a slow rate charge going ASAP after hitting that dangerous low point.

And leaving at dead flat for more than a day will do more damage than a few hours, a week lots more than a day, etc.

A **slow** discharge rate just means more thorough flattening, just like using the same end-charge setpoint, a low amp rate gets to higher SoC than when fast charging.
 

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None of this is to say you should not test, just do not set expectations high.

Most batteries these days do have LVC protection internally, and self discharge rate for bare-cell LFP is well under 10% per year, at least in cold ambients.
 
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