Battery charge and Q2E42
Richard A. Smith
richard at laptop.org
Wed Feb 17 14:48:25 EST 2010
On 02/17/2010 12:25 AM, Mikus Grinbergs wrote:
> As I said, it may be the battery. But I am surprised at how RAPIDLY
> that battery went from nearly fully charged (at the beginning) to nearly
> empty (with Q2E42, etc.), and how RAPIDLY that battery went from 18%
> charged (on Q2E42b) to 80% charged (on Q2E41, different machine).
The EC code between q2e41 and q2e42* are binary identical so its not
anything introduced by new firmware. I'm not going to introduce any EC
instability into the mix until later.
State of charge has a lots of different ways that it can get out of sync
with reality. There are some sync points where the EC will try to
correct the % value to specific values based on various criteria.
A month or so ago while in China I fixed a EC XO-1.5 bug where on
battery recognition after a EC reset it can mess up the SOC %. This bug
is also present in current XO-1 firmware. You don't see it much since
you don't reset the EC much. Flashing firmware resets the EC. So its
possible you hit that bug.
Rapid changes in SOC are usually a sign that the EC detected that SOC is
out of sync with the battery and is trying to correct.
If you want to investigate further then you can use olpc-pwr-log in a
terminal to look at whats going on.
More info here:
Richard A. Smith <richard at laptop.org>
One Laptop per Child
More information about the Devel