What Constitutes a Puffed Lipo?
Every time I go back and review the horror stories about damaged lipos going off, It gives me a renewed sense of fear and dread. I have especially become fearful of storing a good number of the batteries I have been using regularly, which not that long after use have developed a slight puffiness. My battery habits are good except for one area...I am guilty of leaving charged batteries unused for periods of days-to-weeks. If my batteries are indeed puffed, I would suspect this may be the cause.
My problem is that I am not sure how one defines a battery as being swollen, or puffed. These batteries exhibit no real operational issues, and seem to charge and discharge in a normal manner. Is an acceptable battery considered to be one that exhibits absolutely NO swelling at all? Does even a slight bit of puffiness dictate disposal?
The half dozen batteries in question get regular use, and all have developed what I would have to describe as a very slight bit of puffiness. If I squeeze them, they depress perhaps 1/8" to 3/16." They seem to have settled into their current state, and don't appear to show increasing puffiness.
The photo shows a disassembled DBY 3S 30C 1000mah battery, one of two that I fly frequently. Both exhibit the same degree of very slight puffiness. I also show the other battery on it's side. The puffiness is hard to detect, and is most evident by squeezing it. The other one is a Turnigy nano-tech 2s 950mah 25-50C that exhibits the same very slight puffy condition.
Even in the split battery it is hard to see the puffiness, and it's more evidenced by squeezing. A slight bit of the "puffy" look of the middle cell is actually from the force of pulling the cells apart and freeing the adhesive.
So I guess the essential questions are, Does a truly healthy battery remain absolutely flat throughout most of it's life? Is even a slight puff a sign of danger that requires disposal...even though the operational characteristics appear normal?