# [geeks] anyone know Vaios?

Jochen Kunz jkunz at unixag-kl.fh-kl.de
Fri Apr 6 05:52:56 CDT 2012

On Fri, 6 Apr 2012 05:05:03 -0400 (EDT)
Mouse <mouse at Rodents-Montreal.ORG> wrote:

> According to envstat -r, the battery is at 100% charge, but its voltage
> is only some 3.9V, vs a design voltage of 11.1V.
There is somthing fishy. 11.1 V / 3 = 3.7 V and this is the nominal /
average voltage of a LiIon cell. Minimal discharge voltage is,
depending on cell type, around 3 V. So you should have at least around
9 V when the pack is fully discharged. Max. charge voltage is 4.1 V
to 4.2 V, again depending on cell type. So a fully charged pack should
be around 12.6 V.

The cells in that pack are dead. The BMS detects this due to the
undervoltage. Charging these cells can be dangerous. Some LiIon cells
can burn or even explode when charged in this state. Now the BMS
refuses to charge the cells - fortunately. E.g. by cutting off the
charge current with a transistor. So the charge current is 0.0 A and a
charge current under a certain level is the criterion for a fully
charged cell. Hence the 100% charge output.

You need a new battery pack - or at least new cells for the old one.
--

\end{Jochen}

\ref{http://www.unixag-kl.fh-kl.de/~jkunz/}