power consumption after shutdown

pgf at laptop.org pgf at laptop.org
Fri Feb 13 23:35:39 EST 2009

benjamin m. schwartz wrote:
 > Hash: SHA1
 > Mikus Grinbergs wrote:
 > > I take this to mean that *something* was draining some 
 > > power for the two days the XO was sitting in its "shut down" state.
 > All rechargeable batteries lose stored energy over time.  The phenomenon
 > is called "self-discharge".  It is sometimes modeled as a large (but not
 > infinite) resistance in parallel with the battery.

but self-discharge takes place whether a battery is installed in
the laptop or not.  i suspect what mikus is seeing is the effect
of the embedded controller (the "EC") needing a small amount of
current in order to be able to observe the power button press,
which tells it to turn the rest of the system on.

mikus -- when you power up the system after two days, what does
sugar, or olpc-pwr-log, tell you about the state of the battery? 
i suspect it's pretty close to full, but that it needs a small
"top up".  (which is why the light turns yellow.)

(i'm sure richard has numbers for the power-off drain from the
EC, and for the powered-off shelf life of a fully charged

 paul fox, pgf at laptop.org

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