AW LiFePO4 Voltages

[awyeah]

Just got some AW LiFePO4 16340-sized cells and tested them out.

I ran one in my Eagletac D25C until it dimmed significantly - and when I pulled it out of the flashlight, it measured at about 1.5 volts, but quickly recovered to 2.44 volts. AW says not to discharge below 2V - but the 1.5V measurement was under load. Is this cell still okay?

I know we have a general mapping for li-ion cells for voltage vs. capacity - what about for LiFePO4s?

 

[Shadowww]

LiFePO4 is "still okay" no matter what you do to it, at worst you'll lose some capacity. But it'll never turn into a time bomb waiting to explode, unlike Li-Ions.

 

[awyeah]

LiFePO4 is "still okay" no matter what you do to it, at worst you'll lose some capacity. But it'll never turn into a time bomb waiting to explode, unlike Li-Ions.

True, I'm aware of that. I'm just unfamiliar with how they work - I don't mind losing a little capacity here and there, as I've got tons of primaries stored away for emergencies... but the voltage sag and subsequent recovery has me scratching my head. What's the proper way to measure these things?

 

[awyeah]

You know, I might have just answered my own question. On the CPF Marketplace thread where AW is selling these cells, he states:

If you accidentially goes lower than 2V and it recovers after rest, they are still good. I have tried draining them down to 1.5V and they recovers OK. I drained one further down to 0.5V and it was dead and wouldn't accept charge.

So I guess it's okay. And, even if I do accidentally kill a cell to the point where it won't accept charge... I'm not too worried, they're inexpensive and after just a few charge cycles they've paid for themselves anyway.

 

[BenChiew]

I killed one of mine. Ran 3 cells configuration on a 600ma light. Lasted 45minutes till it dimmed significantly. The one that died had only 0.22v and would not charge. And that is immediately pulling out from the light.

 

[HKJ]

I ran one in my Eagletac D25C until it dimmed significantly - and when I pulled it out of the flashlight, it measured at about 1.5 volts, but quickly recovered to 2.44 volts. AW says not to discharge below 2V - but the 1.5V measurement was under load. Is this cell still okay?

It is not "under load" when you take it out of the light, it will immediately recover some voltage.
This kind of discharge might have cost some of the cells capacity.

 

[awyeah]

It is not "under load" when you take it out of the light, it will immediately recover some voltage.
This kind of discharge might have cost some of the cells capacity.

That's true - I should have said "it was just under load" ;)

 

[Viking]

I just ran one down to 1.1 volt the other day. It also quickly recovered , and accepted recharge.

 

[MattSPL]

I ran one down to 0.8v before and it still works fine.

 

[scaru]

I left mine in a dead short over night and it still charged up fine. :P

 

[TEEJ]

I crucified mine, and put it in a cave with a giant rock across the opening after it died. Later, I discovered it had moved the rock, and must have been alive again.

:D

 

[MattSPL]

:crackup: