macOS Battery Health Interpreter

Cycle count and condition from a report you already have, read correctly.

What you paste

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The Battery Information section from System Information, or ioreg output

How this reads your output

Cycle count, condition and capacity are read from the report, and health is computed as full charge capacity against design capacity where both are present, which is more informative than the rounded percentage macOS displays. The cycle count is set against the 1,000-cycle rating recent Mac laptops carry, with the important caveat attached: that rating is a design target rather than an expiry date.

What the results mean

Cycle count: Complete discharge equivalents, not charge events. Using 50% twice is one cycle, which is why the number rises more slowly than people expect.
Condition: The system own assessment. Anything other than Normal means macOS believes the battery may cause unexpected shutdowns under load.
Capacity against design: What the battery holds now compared to when it was new. Below 80% is noticeably shorter runtime; below 70% is usually worth replacing.

Common problems and fixes

Capacity dropped several percent in a week: Battery controllers estimate capacity and re-estimate after full charge and discharge cycles, so the reported figure moves in steps rather than smoothly. A sudden drop after a long period at a constant charge level is usually recalibration rather than degradation. Watch it over a month before drawing conclusions.
Cycle count is low but runtime is poor: Look at what is running before blaming the battery. A single process spinning in the background costs hours of runtime, and Activity Monitor has an Energy tab that names the culprits. Heat is the other factor: a battery that has spent its life at high temperature degrades faster than the cycle count suggests.

Frequently asked questions

What counts as a battery cycle?

The equivalent of one full discharge, accumulated in fractions. Using 25% four times is one cycle. That is why a machine charged constantly at a desk accumulates cycles slowly while a laptop used unplugged all day accumulates them quickly.

Should I let the battery run down before charging?

No. That advice belongs to nickel chemistry, which is long obsolete. Lithium cells prefer partial discharges and dislike being held at full charge, which is why macOS has optimised charging that pauses at 80% until you need the rest. Leave it on.

When is a battery worth replacing?

When the condition changes from Normal, or when capacity falls far enough that the machine no longer lasts through the work you do unplugged. Below about 80% of design capacity the difference is noticeable, and below 70% it is hard to ignore.

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