How to Monitor Laptop Battery Health Over Time in Python

import time
import json
from pathlib import Path
from datetime import datetime

try:
    import psutil
except ImportError:
    print("psutil required: pip install psutil")
    exit(1)

LOG_FILE = Path("battery_health_log.json")

def monitor_battery(log_interval=60, duration=300):
    """Log battery percentage and remaining time every `log_interval` seconds."""
    if not LOG_FILE.exists():
        with open(LOG_FILE, "w") as f:
            json.dump([], f)

    start = time.time()
    while time.time() - start < duration:
        battery = psutil.sensors_battery()
        if battery is None:
            print("No battery detected.")
            break

        entry = {
            "timestamp": datetime.now().isoformat(),
            "percent": battery.percent,
            "power_plugged": battery.power_plugged,
            "secs_left": battery.secsleft if battery.secsleft != -1 else None
        }

        with open(LOG_FILE, "r+") as f:
            data = json.load(f)
            data.append(entry)
            f.seek(0)
            json.dump(data, f, indent=2)

        print(f"Logged: {entry['percent']}% | Plugged: {entry['power_plugged']}")
        time.sleep(log_interval)

if __name__ == "__main__":
    monitor_battery(log_interval=10, duration=30)  # Short demo: 3 entries over 30 seconds