def get_battery_energy_full(battery_id):
    """
    Get the maximum energy stored in the battery

    :param battery_id: Battery ID/Number e.g. BAT0
    :return: maximum energy (int)
    """
    with open(f'/sys/class/power_supply/{battery_id}/energy_full') as f:
        battery_percentage = int(f.read())
    return battery_percentage