Quote:
Originally Posted by mr emily
I read with interest all of the comments and recommendations about charging lipos. Makes you a bit wary about these things, although I recall the odd nmhi going pop. Not as catatophic unless you were close by!!
What I want to know is when should you dispose of a lipo. How much swelling is acceptable, any at all? What other defects commonly occur which render them suspect.
Do the BRCA ,Electric Board, have guidlines?
Keith
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Keith,
My research so far suggests that the most common cause of cell failure during early life is manufacturing faults. These manifest themselves in the early life of a cell. Bearing in mind cells are designed for lives of 300 to 500 cycles, our use at race meetings, where we might get 20 uses in a month at best, counts as early life.
Swelling has multiple causes. Cathode materials can vaporise and decompose, gases can be released at temperatures above 60C in both charge and discharge cycles and local shorting can occur where the polymer separator material melts and prevents a short, but releases gas.
No one, not even the Government departments in UK, US and Japan know for sure what amount of swelling is 'acceptable'. For as many opinions there are as many counter-opinions. We simply do not know.
This thread is getting to the point where people might think we are all going to hell in a handcart. We are not. This technology is good for our sport and in the wider commercial market (something like 6 billion Li-ion-technology cells were shipped around the world last year either individually or in products with less than 20 reported incidents) the risks are considered acceptable for use to use, and aircraft to ship. Let's keep it in proportion and talk about reducing risk, not eliminating all possible incidents.