OH CHEET!

[PlayboyJoeShmoe]

I got a pair of Ultrafire 2400 un-protected at LightHound today.

Just checked them and found one at .9V

It is ruined isn't it?

I have it by itself on my DSD charger right now. But if it's toast I'll see about getting it replaced.

 

[cheetokhan]

I got several different cheapo RCR123 cells from DX a while back so I could play with my West Mountain CBAII battery tester. 3 of the cells arrived with very low charge but I was able to get them to recharge. They had very low capacity and they all died completely after just a few charge cycles.

 

[moldyoldy]

Kaput? not necessarily. charge it and try using it first.

Based on the "2400" capacity, that must be the Ultrafire unprotected 18650 cell. I have unfortunately used/abused the unprotected Li-Ion cells in a __single__ cell light down to well below the accepted minimum without any obvious problem. However, do NOT deep discharge Li-Ion cells with any lights using two or more Li-Ion cells!! Not recommended! normally as soon as the light dims with unprotected cell(s), swap cells! I normally do not carry a backup cell, so when the runtime is "gone", I still have some light left rather than being left in the dark by a protected cell that cut out.

 

[metlarules]

I would definitely have it replaced.

 

[BVH]

I'd play it safe and get it replaced.

 

[Fallingwater]

The cell is damaged, but not necessarily dead.
The safe thing to do would be to ask for a replacement and toss it; the less safe thing to do is to use a variable power supply to *slowly* bring it back to 3 volts, then put it in a charger and hope for the best. Note that it's conceivable this could cause the cell to blow, so you're doing it at your own risk - please take the proper precautions.

 

[supergravy]

Just be happy you bought it where you did. :thumbsup:

 

[LuxLuthor]

I know that quite a few Li-Mn Ion battery (using Sanyo, Emoli, Sony cells) packs for various power tools (i.e. Ridgid, Ryobi) ship intentionally with very low voltages like this. Their rationale in product circular was to avoid accidental high voltage/amp discharge events. I do know that they all charged up normally, and appear to have the expected, advertised mAh & amp output characteristics. I do not know if their total number of cycles will be reduced...but this is a standard practice with at least some of these pre-built tool packs.

I don't know if Ultrafire has the same strategy or quality control.

 

[PlayboyJoeShmoe]

DSD had it up to 3.87 just a bit ago.

DSD always stops at no more than 4.1.

I run these as singles. Not in pairs. I'll see how it goes.

Cheap enough to buy more. Will know to check 'em before buying next time!

 

[mdocod]

Think of a li-ion cell like a swimming pool. Think of voltage like pH (sort of). When the voltage goes above 4.20V, or below 3.5V, think of it like the acidity of the pool water going too high. The longer the pool waters remains acidic, the more damage is done to the heat exchanger (which is made of copper). Now imagine that the separator materials within a li-ion cell are like the heat exchanger for the pool heater. But in the case of the li-ion cell, if the separator materials are compromised, you can develop an internal short, the final failure is most likely to happen during charging.

I would not even take delivery on a lithium cobalt cell measuring less than 3.6V.