[arch-general] POWER_SUPPLY_CHARGE_FULL(_DESIGN) semantics

[Chrisitan Burkard]

Hi,

I am wondering what the semantics of POWER_SUPPLY_CHARGE_FULL(_DESIGN)
are. I am using a ~3 years old thinkpad with its first battery so aging
is something normal I guess. (see below).

[watnuss at tp ~]$ cat /sys/class/power_supply/BAT0/uevent
POWER_SUPPLY_NAME=BAT0
POWER_SUPPLY_STATUS=Unknown
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_CYCLE_COUNT=0
POWER_SUPPLY_VOLTAGE_MIN_DESIGN=11100000
POWER_SUPPLY_VOLTAGE_NOW=12484000
POWER_SUPPLY_CURRENT_NOW=0
POWER_SUPPLY_CHARGE_FULL_DESIGN=7800000
POWER_SUPPLY_CHARGE_FULL=5052000
POWER_SUPPLY_CHARGE_NOW=4551000
POWER_SUPPLY_CAPACITY=90
POWER_SUPPLY_CAPACITY_LEVEL=Normal
POWER_SUPPLY_MODEL_NAME=42T4799
POWER_SUPPLY_MANUFACTURER=SANYO
POWER_SUPPLY_SERIAL_NUMBER= 5878

As I understand POWER_SUPPLY_CHARGE_FULL_DESIGN would be the capacity of
a fully charged new battery and POWER_SUPPLY_CHARGE_FULL is the maximum
capacity of the battery today.

I am asking because I am using i3status to show my battery loading state
and it shows me 58% which would be (CHARGE_NOW / CHARGE_FULL_DESIGN). If
I understand correctly this doesn't make any sense if I am not able to
reach the CHARGE_FULL_DESIGN capacity anyways, today.

So if anyone with a bit more knowledge about this mechanic could confirm
my guess I would contact upstream what they think about it. (In my
opinion they should read CHARGE_FULL to determine the current battery %)

Another issue I have is that the POWER_SUPPLY_STATUS shows 'Unknown' on
AC but 'Discharging' on Battery. Do you have any idea why? My guess is
that i3 uses this property to show the battery/AC state in i3status and
because of the 'Unkown' value I don't get updates on the state there.

Best regards and thanks for your help

Christian