DiePo4 - Can I bring a LiFePo4 cell back from 70mV?

[ahend]

Took off on my bike this morning and hit the cutout voltage about a 1/2 mile into the commute. I took apart my Golden Motor 36V 10Ah LiFePo4 pack and found a dead cell, well 70mV, dead enough. The pack seemed to charge and balance ok last night via the supplied balance charger and I do not see evidence of any direct shorts.

During the day I put the cell on a trickle charge, trying to resuscitate it. I started with 100mA @ 3V for a few hours until it hit a wall at 150mv. I then increased the current to 200mA with the same voltage and got it to 250mV in another couple hours.

I wonder if I’m wasting time here. Does any have a recipe to bring a LiFePo4 cell back from the grave? I cannot seem to locate any good information about this.

 

[kbarrett]

Once they go to zero or reverse polarity, you should probably consider that cell in the battery gone.

Maybe ask the vendor to send or sell you a replacement cell?

 

[ahend]

Maybe ask the vendor to send or sell you a replacement cell?

Yeah, I'm on that but it's like pulling teeth. The pack has a total of 5 cycles on it!

 

[ahend]

Very strange things afoot. I got the cell back home and noticed it was a bit warm. Checking the voltage I found that it went from 250mV to 2.88V during the transit home. Continuing to trickle at 100mA . . .

 

[pwbset]

 

[kbarrett]

Loose crimp, maybe?

 

[ahend]

Loose crimp, maybe?

I have the cell isolated and I'm reading voltage at the odes directly.

Voltage has now dropped back down to 125mV. Perhaps it was the last of the death throes. Head for the light little buddy!

Anyone have any spare 10Ah cells for sale. My cells are apporoximately 42mm in diameter and 109mm long. Max discharge current is 35A, max continuous discharge current is 20A. Im not sure what you would call the package.