Is this 10440 cell bad?

[crizyal]

I purchased 2 AW 10440 Li-ion batteries about 6 months ago. Neither battery has seen any abuse (deep discharge, overcharge, heat). I noticed that one of the cells is coming off of the charger (UltraFire WF-138) at 3.98V while the other seems normal coming off at 4.16V. I use both of these cells in a single cell light (LFX2T). Is this lower voltage cell displaying characteristics of a cell that should be recycled? I would like to continue to use this cell if it is considered to be reasonably safe. I would simply recycle the cell if the chances for venting are high. What do the battery experts think? Thank you.

 

[45/70]

One thing you may want to make sure of, is the cell that comes off the charger at 3.98V making proper contact with the contacts in the charger?

I don't know whether you have AW's newer Soshine 10440's, or the older blue wrapper ones, but the older blue cells are basicaly "flat tops" and sometimes it is difficult to ensure proper contact in the charger. I have no experience (yet) with the Soshine 10440's, but they may have the same problem.

If the cell is making proper contact in the charger, then yes, that is a sure sign that it's time to discard/recycle the cell. If a LiCo Li-Ion cell won't hold at least 4.00 Volts, it is at EOL.

Dave

 

[crizyal]

It is a blue wrapper cell. I do believe that it is making good contact because the charger does charge the cell some. Right after the charger terminates I get a reading of 3.98V. I am not sure if it is a good idea, but I did put the cell back into the charger and it started the charging sequence again. When the charger terminated the second time, I measured 3.98V again. I must have just been unlucky with this cell, the other cell purchased at the same time and cycled the same is in great working order. By the way these cells probably only have 8 cycles on them. How many cycles should I expect with a cell like this?

 

[crizyal]

After letting the cell rest for an hour, the voltage dropped to 3.95V. I will recycle this cell. Thank you!

 

[45/70]

After letting the cell rest for an hour, the voltage dropped to 3.95V. I will recycle this cell. Thank you!

Yeah, sounds like it's all over for that cell.

As for your question as to how many cycles you should expect to get from these cells, I have two of the "LC" (blue wrapper) 10440's I got from AW about 4 years ago for my Extreme III's. These cells probably have about 40-50 partial cycles on them. They have never been discharged to below 3.7 Volts OC (I usually try to stop at 3.8 Volts), and when unused are stored in the fridge with a ~40% charge at 35-40F. When charged to 4.20 Volts and then "rested" for a day, they both read ~4.16 Volts.

It is often said that LiCo Li-Ion cells nowadays have about a 5 year calendar life. With proper care, and depending on how they are used, it appears that this can be extended considerably. I have other LiCo cells that have been cycled more, and used under higher than recommended current loads, that still hold 4.05 Volts. Some of these cells are close to 5 years old. There are a lot of variables that determine how long LiCo cells will last, but I'd say you probably just had a bad cell.

Dave