What is battery health?
The short answer
Battery health is a percentage that tells you how much charge your battery can hold compared to when it was brand new.
What does the percentage mean?
When your phone or laptop is new, its battery health is at 100%. Over time, every charge cycle wears the battery down slightly, and that number drops.
- 100-90% — Your battery is in great shape. No action needed.
- 89-80% — Normal wear. You might notice slightly shorter battery life.
- Below 80% — Your battery has degraded significantly. You will likely notice your device dying faster than it used to.
For example, if your battery health is at 85%, it can only hold 85% of the charge it could when it was new. A phone that once lasted all day might now need a top-up by mid-afternoon.
How to check it
- iPhone — Go to Settings > Battery > Battery Health & Charging.
- Android — Go to Settings > Battery > Battery Health (varies by manufacturer).
- Mac — Hold Option and click the battery icon in the menu bar, or check System Settings > Battery.
- Windows — Open Command Prompt and run
powercfg /batteryreport, then open the generated report.
When should you worry?
You should start thinking about a replacement when battery health drops below 80%. At that point:
- Your device may shut down unexpectedly at low charge levels
- Performance may be throttled to prevent crashes
- You will need to charge more often throughout the day
How to keep it healthy longer
- Avoid extreme heat — heat is the number one battery killer.
- Don’t charge to 100% constantly — keeping it between 20-80% helps.
- Use optimized charging if your device offers it — it learns your routine and slows charging overnight.
- Avoid cheap, uncertified chargers — they can deliver inconsistent power.
Battery degradation is normal and happens to every rechargeable battery. You cannot reverse it, but you can slow it down with good habits.