recovering dead ducks 0V LiFePO4's what's your best guess on procedure?

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terramir
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recovering dead ducks 0V LiFePO4's what's your best guess on procedure?

now this is a real interesting question, after that cell blew up (popping noise smoke probably black particulates) I went the way of turning things down (chargers to 3.55V from 3.65V and precharger down to 75mA constant current vs 100mA before).
But here's the thing I wasn't thinking of the charger where the cell blew was limping anyways, it was running at a voltage input which caused the current to be 130mA max instead of a healthy 485mA max. So maybe the constant slow current didn't give the cell a chance to really recover in the internal chemistry and this might have been what caused it to blow, instead. maybe I trickled that cell to death LOL.

three proposed procedures here:
A: charge with the pre-charger @ 100 to 120mA (comments welcome if it should be the highest possible for this circuit) until it reaches between 3.2 and 3.38V (the cutoff point varies a bit with this circuit I just discovered) and then charge it with the charger that has a constant voltage of 3.65V but ensure that the current is high untill the cell decides to lower it itself.
B: pre-charge with a slower rate (50 to 75mA) and then ensure the charger has no more than a 250mA current rate.

At this time I'm open to suggestings since the cells seem to be taking forever to charge
Other choice would be lower cut-off voltage on the precharge( like somewhere in the 2V range) and well then the options for regular charging stay pretty much the same.
terramir

Mik
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Re: recovering dead ducks 0V LiFePO4's what's your best ...

Maybe you can put all your 0V cells in parallel and then connect them to a 3V DC power supply.

Those cells that recover will not get over charged that way. You can leave them connected for weeks or months and check every now and then if any of them have been resurrected to more than 0V. The charge the recovered ones up at a faster rate and leave the others on the 3V supply until you are sick of waiting...

What voltage does your pre-charger need to apply to get 100mA (or 75mA) to flow through the dead cells?

This information may be used entirely at your own risk.

There is always a way if there is no other way!

terramir
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Re: recovering dead ducks 0V LiFePO4's what's your best ...

it's opamp forced so I don't really know the total voltage is 4.7V to 5.15V and the voltage rises as it pleases. i.e. as the cell goes up. as for the regular charger it can supply a max of about 1/2amp and it supplies whatever voltage I set meaning up till now exactly the cut-off voltage (max voltage 3.65V) however the cells stop pulling current around 3.62 to 3.64V and once taken out of the charger start dropping slowly if full in a day or two there down to 3.35 to 3.29 volts.
I was actually thinking about putting a metal plate in the bottom of the box and putting electrodes screws at the top (so I can measure each cell) of the cardboard box 50 come in a box LOLz and charging em with the 3.3V rail of the psu I use. Well I wonder how many cells will charge that way LOL.
Any other suggestions?
terramir

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