rottenray:
I read somewhere that temp sensing is overall, rather than cell by cell.
A temp sensor per cell becomes more important where fast charging is used.
There will be significant temperature rise and that coupled with a low
max temp of 65 C means that a single temp sensor to cover such a large
area is not enough. From what i've read, the fast charge timescale is about an hour
30mins.
Given the relatively "light" weight of these cells, and the
corresponding lower rate of thermal inertia, I'd guess that a cell could
overheat in one area before a sensor located on the opposite side could
sense the climb. Perhaps thermal curves could be modeled to predict
this, but if I were designing the bugger I'd certainly have at least 2
sensors per cell.
2 would provide redundancy, but if the temp and voltage sensing were
combined into a single chip device, it could be embedded into the cell
casing at very little cost and have enough diagnostics to detect either
the voltage or temp sensor's failure.
There's another point as well: It looks like there are printed circuit
boards inside the battery casing. Hmm: pcb's + electrolyte = trouble,
even if the boards have a conformal coating. You only need a single cell
case to split, for whatever reason and you have electrolyte and vapour
which could play havoc with electronics. Inside a battery casing is
the last place I would put a pcb, especially if that is handling the
sensors
Regards,
Chris