From: Fustos Janos (janos6662000_at_yahoo.com)
Date: Wed Aug 14 2002 - 17:42:10 EDT
I borrowed a battery for my 770Z and haven't used it
for a while, let's say 3 weeks. The battery worked OK,
provided about 3 hours of use.
Yesterday i wanted to use it again, no power.
Connected it to charger, charging starts, indicates 0%
but stops after a few seconds.
I left it overnight, but still nothing.
Today i took apart the battery. (I am a hardware
engineer).
The battery pack is made of 9 cells, every 3 cells
linked in parallel, and after the 3 groups in a serial
connection.
One of the 3 cell battery groups has negative
voltage!!!
The polarity is marked in clear on every cell, but now
on the positive side i have negative voltage, related
to the other side.
If i apply a supply voltage, any small current ( i
tried to apply the voltage through a 10MOhm resistor),
the voltage becomes normal, after i cut the supply
voltage becomes negative again.
Oh, i forgot to say, i desoldered the cells from the
PCB, not to ruin any of the control electronics.
Any ideas?
How can a Li-Ion cell invert its voltage?
Any chance to save the battery pack? Maybe to "format"
it again under correct parameters?
Thanks in advance,
Janos
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