Check laptop battery on linux

Use the upower command. UPower provides an interface to enumerate power sources on the system and control system-wide power management. Click here for more information.

At the command line run  upower -e to enumerate the the object paths of the available devices (including battery). Then run upower -i <object_path> to get the info. For example (in my laptop):

$ upower -i /org/freedesktop/UPower/devices/battery_CMB1 
  native-path:          CMB1
  vendor:               Fujitsu
  model:                CP656340-01
  serial:               02B-S170905000249S
  power supply:         yes
  updated:              Πεμ 04 Οκτ 2018 11:39:20 μμ EEST (52 seconds ago)
  has history:          yes
  has statistics:       yes
    present:             yes
    rechargeable:        yes
    state:               fully-charged
    warning-level:       none
    energy:              70,0312 Wh
    energy-empty:        0 Wh
    energy-full:         70,0312 Wh
    energy-full-design:  72 Wh
    energy-rate:         0 W
    voltage:             12,819 V
    percentage:          100%
    capacity:            97,2656%
    technology:          lithium-ion
    icon-name:          'battery-full-charged-symbolic'