Comment by Nephx

Simple command line utility to display charging (or discharging) rate in watts on linux. You might have to modify battery_directory and the status/current_now/voltage_now names based on laptop brand, but Lenovo, Dell and Samsung seems to use this convention.

    #!/usr/bin/python3

    battery_directory = "/sys/class/power_supply/BAT1/"

    with open(battery_directory + "status", "r") as f:
        state = f.read().strip()

    with open(battery_directory + "current_now", "r") as f:
        current = int(f.read().strip())

    with open(battery_directory + "voltage_now", "r") as f:
        voltage = int(f.read().strip())

    wattage = (voltage / 10**6) * (current / 10**6)
    wattage_formatted = f"{'-' if state == 'Discharging' else ''}{wattage:.2f}W"

    if state in ["Charging", "Discharging", "Not charging"]:
        print(f"{state}: {wattage_formatted}")

Output:

Charging: 32.15W

Discharging: -5.15W