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Glossary

Glossary · 用語

Battery health.

Battery health is the current maximum capacity of your MacBook’s battery, expressed as a percentage of its original design capacity. A new battery starts at 100%; macOS marks it “Service Recommended” at 80%.

Battery health is easy to confuse with state of charge, which is how full the battery is right now. Health is the ceiling; charge is the level. A perfectly healthy battery can be at 12%, and a heavily worn one can be at 100% — they’re measuring different things.

Health drops gradually. A typical curve looks roughly like 95% at 200 cycles, 88% at 500, and 80% at 1,000 — the design target. Heat and time spent at high charge push the curve down faster.

macOS surfaces two values in Settings → Battery → Battery Health: Maximum Capacity (the percentage) and Condition (Normal or Service Recommended). Apple replaces the battery at no charge if it’s below 80% during a valid AppleCare plan — see Apple’s service notes. Below 80% doesn’t mean the battery is broken; it just means it holds less of what it used to.