I managed to disassemble and repackage the li-ion cells from one
of these toshiba PA2487U battery packs. The case is removed and
I have three groups of three cells connected together with some
stranded wire. The original contacts that mated with the charger
have been removed, and I now have a four foot cable between the
battery and charger, stranded wire for pos and neg, ribbon cable
for the data pins (8 conductors). I was able to solder all of
these wires right onto the small PCB inside the battery pack.
The original battery pack protection/control circuit is still in
place, and the original charger is charging it right now. I will
be adding a quick-disconnect on the cable just to prove that
this concept is viable (modifying existing charger/packs). I
noticed that the cells are laid out in an interesting way inside
these battery packs, like this:
|-----------------> | |
+ + + - - - | + + + | |
-------------------------| ---------------> | |
| | | | | | | | | | C |
C C C C C C C C C | I B|
E E E E E E E E E | R O|
L L L L L L L L L | C A|
L L L L L L L L L | U R|
| | | | | | | | | | I D|
----------| ----------------------------> | T |
- - - | + + + - - - | |
|--------------------------------> | |
Notice that each group of three cells is parallel connected.
This implies that each cell is 3.6V 1200 mah, three parallel
are 3600 mah. Then the three groups are connected in serial
to get to 10,8V. But the groups of three cells are not just
wired together as a chain of positive-to-negative, instead
that connection is made on the little circuit board inside
the pack. Its interesting how the first group of cells is
wired serially to the second group (only on one pole) and the
second group is wired to the third (only on one pole). I am
guessing that this is for safety, the final connection will
only be made (on the pcb) if the conditions are right (temp,
voltage, current, etc). Has anyone popped open a NP-F960 to
see what's inside?
-- Doug
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