[Gta04-owner] Now that 3.2-final is out...

[Flemming Richter Mikkelsen]

On Sun, Jan 15, 2012 at 22:36, Neil Jerram <neil at ossau.homelinux.net> wrote:
> Neil Jerram <neil at ossau.homelinux.net> writes:
>
>> I just compiled a new kernel from 3.2-gta04 (bb54650b).
>
> I did an experiment to measure how long my battery will last for, with
> the Phoenux on -- not suspended -- but not doing anything and with all
> RF killed; and also to look for any strange patterns that might indicate
> that my battery is no good.  I'd appreciate if battery-knowledgeable
> people could take a look and let me know if they see any cause for
> concern here.
>
> The battery lasted 264 minutes before the Phoenux switched off.  The
> attached graphs show voltage, discharging current and capacity (all from
> /sys/class/power_supply/bq27000-battery/uevent) against time in minutes.
>
>
>
> For what they're worth, my observations are as follows.
>
> - The gradual decrease in voltage (over most of the time period) matches
>  how people have said the battery behaves - in particular in connection
>  with needing >= 3.8V for the Phoenux to boot up.
>
> - I guess that the gradual increase in current is to compensate for this
>  decrease in voltage, assuming that the components in the system
>  require a constant amount of power.
>
> - I have no idea what causes the much sharper decrease in voltage, and
>  matching increase in current, a few minutes before the Phoenux
>  switches off.

This looks like an effect caused by internal resistance changing and to
me it looks exactly as I expected.

Anyway, I am not an expert in this...  maybe you find a chemical explanation
at wikipedia (if you look up this battery type)?