XO power management

Paul Fox pgf at laptop.org
Thu Mar 24 08:50:42 EDT 2011

ismael wrote:
 > Hello everyone, I'm trying to perform some tests on XO battery life
 > performance and I have some questions which I couldn't find a clear answer
 > in the wiki or this list:

i'm sure richard will chime in, but here's a start.

 > - When the battery level is "critically low" the OS (Sugar 0.88 based
 > Dextrose) performs a safe shutdown. I would like to know what is the exact
 > condition that triggers this.

the answer to this depends on what version of powerd is running.  in
the latest powerd versions, we force a shutdown if the capacity is 1%
(or less :-), or if the battery voltage is 5.7V or less.  we don't
bother with these checks unless the capacity is below 40% (which may
be a pointless optimization).  these checks were slightly different
in powerd versions 27 and earlier, but i suspect dextrose is running
something newer than that.

 > - Likewise, at some level controlled by the XO EC, the battery led light
 > begins to flash orange/red. I would also like to know which is the exact
 > condition that triggers this. Is it the SOC, battery voltage, ACR... ? And

i believe this value is 5.7V.  (i.e., battery voltage)

 > what level triggers this condition? I would also like to know the level in
 > which the XO performs a "hard" poweroff.

5.5V on XO-1.5, 5.4V on XO-1.

also remember that the voltage at the battery will change, substantially,
between the suspended and running states -- so what the EC sees during
suspend may be several tenths of a volt higher during suspend than when
the system is running.


 > Any help is appreciated.
 > Thanks!
 > Regards,
 > Ismael
 > -- 
 > Ismael Schinca
 > Centro Ceibal - Depto. Técnico - I+D
 > Avda. Italia 6201 - Edificio Los Ceibos
 > Montevideo - Uruguay.
 > Tel.: 2601 57 73 Int. 2232
 > part 2     text/plain                 129
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 paul fox, pgf at laptop.org

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