バッテリー状況の確認。

$ cat /etc/debian_version 
9.3

$ ls /sys/class/power_supply/
AC  BAT0

$ cat /sys/class/power_supply/BAT0/
alarm               cycle_count         status
capacity            device/             subsystem/
capacity_level      manufacturer        technology
charge_full         model_name          type
charge_full_design  power/              uevent
charge_now          present             voltage_min_design
current_now         serial_number       voltage_now

$ cat /sys/class/power_supply/BAT0/uevent 
POWER_SUPPLY_NAME=BAT0
POWER_SUPPLY_STATUS=Full
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_CYCLE_COUNT=0
POWER_SUPPLY_VOLTAGE_MIN_DESIGN=14400000
POWER_SUPPLY_VOLTAGE_NOW=15734000
POWER_SUPPLY_CURRENT_NOW=0
POWER_SUPPLY_CHARGE_FULL_DESIGN=2000000
POWER_SUPPLY_CHARGE_FULL=181000
POWER_SUPPLY_CHARGE_NOW=181000
POWER_SUPPLY_CAPACITY=100
POWER_SUPPLY_CAPACITY_LEVEL=Full
POWER_SUPPLY_MODEL_NAME=42T4646
POWER_SUPPLY_MANUFACTURER=SANYO
POWER_SUPPLY_SERIAL_NUMBER= 1864

$ cat /sys/class/power_supply/BAT0/charge_full_design 
2000000
$ cat /sys/class/power_supply/BAT0/charge_full
181000

$ grep CHARGE /sys/class/power_supply/BAT0/uevent |awk -F= 'NR==1{des=$2}NR==2{full=$2}{print $1 " \t= " $2}END{print "CHARGE_FULL / CHARGE_FULL_DESIGN = " full/des}'
POWER_SUPPLY_CHARGE_FULL_DESIGN 	= 2000000
POWER_SUPPLY_CHARGE_FULL 	= 181000
POWER_SUPPLY_CHARGE_NOW 	= 181000
CHARGE_FULL / CHARGE_FULL_DESIGN = 0.0905

(ヽ'ω`)設計値の9%...だと...
まあ元がジャンク品に付いとったものじゃからのう...と思ったのであった
参考: https://superuser.com/questions/808397/understanding-the-output-of-sys-class-power-supply-bat0-uevent