1100mAh 3.2V LIFePO4 rescue if there stored to 0V (selfdischarge new cells)
Question here is the follwoing I can get my hands on many LiFePO4 cells HW 18650P 3.2V 1100mA GD25 Anyway I can get some dirtcheap as in for next to nothing one catch they were not charged during storage and self discharged to 0V the people told me I should be able to rescue about 15% of the cells with a capacity of maybe 600 to 800 mAh.
Any rescue techniques/ experiances with 0V LiFePO4's of the cheaper variety, I know the 123 system batteries have survived that (at least from posts on RC forums).
Please let me know what you know, and what recommendations you have for rescue attempts like for example: charging at like 5mA till it reaches a certain voltage etc.
terramir
0v is way far below the low voltage cutoff of LiFePO4 cells. As I understand it when the voltage falls below the low voltage cutoff the chemicals change state to where they cannot be recharged.
I would suppose you could charge those cells and if some hold a charge then they are okay at diminished capacity, as you say. But I doubt you'll get many usable cells and they won't behave as well as usual.
I tried this recently with the Headway battery pack I have. Two of the cells arrived reading at 0 volts. I took one of the spare wallwarts lying around, it was one that produced 5v at 100mA or so and hooked it up to the battery. Over a few hours the voltage rose to a reasonable level and then the regular pack charger and BMS began to work. It managed to hold a charge for a short time but within a couple hours of removing the charger the cells read 0v again.
I had a mishap with a couple of my thundersky 40ah cells. They got shorted briefly and when I checked the voltage they were at 1.15v and 1.1v. I trickle charged them with a hobby charger till I got them to about 2.5v then I put them back in the pack (which I discharged first) and then charged them with my Thundersky charger. They have been behaving fine so far but I'll keep an eye on them.
well investing 40 bucks for 200 cells is not much and it will be worth it if I only get like 30 usable cells but it definetly be worth it just for the learning experiance. I wonder if methods would have any influance on the cells
terramir