Battery Charge Estimation Fix

Battery Charge Estimation Fix | Generated by AI

Home 2025.08

The error Cannot estimate time to full charge (sysfs files not found) indicates that the script couldn’t find the expected battery information files in /sys/class/power_supply/BAT0/. This can happen if:

The battery is named something other than BAT0 (e.g., BAT1 or another name).
The specific files (charge_now, charge_full, current_now) are not available or have different names on your Lenovo laptop.
The user running the script lacks permission to access these files.

Here’s a fixed Python script that dynamically detects the battery name and handles variations in sysfs file names (e.g., energy_now instead of charge_now for some systems). It also includes better error handling and permission checks:

import psutil
import os
import glob

def find_battery_path():
    """Find the battery directory in /sys/class/power_supply."""
    battery_paths = glob.glob('/sys/class/power_supply/BAT*')
    if not battery_paths:
        return None
    return battery_paths[0]  # Return the first battery found (e.g., BAT0 or BAT1)

def get_battery_info():
    try:
        # Get battery information using psutil
        battery = psutil.sensors_battery()
        
        if battery is None:
            print("No battery detected.")
            return

        # Battery percentage
        percent = battery.percent
        print(f"Battery Percentage: {percent:.2f}%")

        # Check if battery is charging
        is_charging = battery.power_plugged
        status = "Charging" if is_charging else "Discharging"
        print(f"Status: {status}")

        # Estimate remaining time (only when discharging)
        if not is_charging and battery.secsleft != psutil.POWER_TIME_UNLIMITED:
            remaining_secs = battery.secsleft
            hours = remaining_secs // 3600
            minutes = (remaining_secs % 3600) // 60
            print(f"Estimated Time Remaining: {hours} hours, {minutes} minutes")
        elif is_charging:
            # Try to estimate time to full charge using sysfs
            battery_path = find_battery_path()
            if not battery_path:
                print("Cannot estimate time to full charge (no battery found in sysfs).")
                return

            try:
                # Check for charge or energy-based files
                charge_now_file = os.path.join(battery_path, 'charge_now')
                energy_now_file = os.path.join(battery_path, 'energy_now')
                charge_full_file = os.path.join(battery_path, 'charge_full')
                energy_full_file = os.path.join(battery_path, 'charge_full_design')
                current_now_file = os.path.join(battery_path, 'current_now')

                # Determine which files to use (charge or energy)
                if os.path.exists(charge_now_file) and os.path.exists(charge_full_file):
                    now_file, full_file = charge_now_file, charge_full_file
                elif os.path.exists(energy_now_file) and os.path.exists(energy_full_file):
                    now_file, full_file = energy_now_file, energy_full_file
                else:
                    print("Cannot estimate time to full charge (charge/energy files not found).")
                    return

                # Read battery data
                with open(now_file, 'r') as f:
                    charge_now = int(f.read().strip())
                with open(full_file, 'r') as f:
                    charge_full = int(f.read().strip())
                with open(current_now_file, 'r') as f:
                    current_now = int(f.read().strip())

                if current_now > 0:
                    charge_remaining = charge_full - charge_now
                    seconds_to_full = (charge_remaining / current_now) * 3600
                    hours = int(seconds_to_full // 3600)
                    minutes = int((seconds_to_full % 3600) // 60)
                    print(f"Estimated Time to Full Charge: {hours} hours, {minutes} minutes")
                else:
                    print("Cannot estimate time to full charge (current_now is 0).")
            except PermissionError:
                print("Cannot estimate time to full charge (permission denied). Try running with sudo.")
            except FileNotFoundError:
                print(f"Cannot estimate time to full charge (sysfs files not found in {battery_path}).")
            except Exception as e:
                print(f"Error estimating time to full charge: {e}")
        else:
            print("No remaining time estimate available.")

    except Exception as e:
        print(f"Error retrieving battery information: {e}")

if __name__ == "__main__":
    get_battery_info()

Changes Made

Dynamic Battery Detection:
- Uses glob.glob('/sys/class/power_supply/BAT*') to find the battery directory (e.g., BAT0, BAT1) instead of hardcoding BAT0.
- Returns the first battery found or None if no battery is detected.
Support for Charge and Energy Files:
- Checks for both charge_now/charge_full and energy_now/energy_full files, as some systems use energy-based metrics (in watt-hours) instead of charge-based (in microampere-hours).
- Selects the appropriate pair of files based on availability.
Improved Error Handling:
- Handles PermissionError separately to suggest running with sudo if access is denied.
- Provides specific feedback if sysfs files are not found or if current_now is zero.
Formatted Output:
- Limits battery percentage to two decimal places ({percent:.2f}) for cleaner output.

How to Use

Install psutil (if not already installed):
```
sudo pip3 install psutil
```
Save the Script:
- Save the updated script as, e.g., battery_info.py.
Run the Script:
- Execute in a terminal:
```
python3 battery_info.py
```
- If you get a “permission denied” error, try running with elevated privileges:
```
sudo python3 battery_info.py
```
Check Battery Path:
- To verify the battery name and available files, run:
```
ls /sys/class/power_supply
```
  Then, check the contents of the battery directory (e.g., BAT0 or BAT1):
```
ls /sys/class/power_supply/BAT0
```
- Look for files like charge_now, charge_full, energy_now, energy_full, or current_now. If they differ (e.g., energy_full_design instead of charge_full), the script should handle it, but let me know if you need further tweaks.

Debugging Tips

If the script still reports “sysfs files not found,” check the exact file names in /sys/class/power_supply/BAT*. Some Lenovo laptops may use non-standard names or have limited sysfs support.
If you see “permission denied,” running with sudo should resolve it, but be cautious with elevated privileges.
If the battery is detected but no time estimate is provided, it could be due to current_now being zero (common when the system isn’t actively reporting charging current). In this case, the script will fall back to indicating that no estimate is available.

Example Output

On your system (Lenovo XiaoXin-14-IAH8), you might see something like:

Battery Percentage: 49.62%
Status: Charging
Estimated Time to Full Charge: 1 hours, 45 minutes

Or, if files are still missing:

Battery Percentage: 49.62%
Status: Charging
Cannot estimate time to full charge (sysfs files not found in /sys/class/power_supply/BAT0).

If Issues Persist

If the script still fails to find the sysfs files, please share the output of:

ls -l /sys/class/power_supply
ls -l /sys/class/power_supply/BAT*/*

This will help identify the exact file names and permissions. I can then tailor the script further to match your system’s configuration.

psutil Documentation
Linux sysfs Power Supply

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