GTA02 Battery Capacity (Was: Re: More about the GTA02)

Andy Green andy at
Thu Feb 14 17:43:30 CET 2008

Hash: SHA1

Somebody in the thread at some point said:
> On Thursday, Feb 14, 2008, "Kyle Bassett" writes:
>> There is talk about pushing startup power control of the internal devices
>> (wifi, bt, gps, mmc, etc.) to user level, as every user may or may not want
>> certain devices available at bootup/all the time (availability vs.
>> duration).
> Indeed, this along with good realtime stats on power usage and current
> battery level would let people have reasonably accurate predictions of
> their battery life.  It'd be interesting (to me at least) to turn
> on and off the various peripherals and watch my projected battery life
> go up and down accordingly.

GTA02 is capable to dialogue with a "smart battery" that will allow you
to see the battery actual voltage and current flow (together: actual
power) in uA down /sys in realtime, it uses the linux "Power Supply"
class to expose it so it is generic.  (I don't know for sure if it will
ship with such a battery since it is decided in .tw according to
availability and so on, but I hope it will.)

The battery itself learns its cell performance over load and also makes
available its "time to full/empty" estimate down /sys as well in
seconds.  You can see what data is available here:

You can see stuff like this

for i in capacity charge_full current_now present status technology temp
time_to_empty_now time_to_full_now type voltage_now ; do echo -n "$i
" ; cat /sys/devices/platform/bq27000-battery.0/power_supply/bat/$i ; done

 capacity    0
 charge_full    1215585
 current_now    183375
 present    1
 status    Discharging
 technology    Li-ion
 temp    276
 time_to_empty_now    0
 time_to_full_now    3932100
 type    Battery
 voltage_now    2761000

- -Andy
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