Glossary · 用語
Watts in / out.
Watts in / out is the real-time rate of energy flowing into or out of your MacBook’s battery, in watts. Positive watts in = charging; positive watts out = running on battery; near-zero balance = the system is pulling exactly what the adapter provides.
macOS doesn’t surface this number natively — only the abstracted “time until full” or “time on battery” estimate. Sensei reads the wattage directly via IOKit and shows it live in the menu bar.
Three reasons to care about the raw watts number:
Diagnosing an underpowered adapter. If the laptop pulls more than the adapter supplies under load, the balance is zero or negative — and the battery drains while plugged in. Watts in / out makes this visible in seconds. Spotting a hung app. When watts-out spikes with no obvious cause, an app is doing background work it shouldn’t be — pair with energy usage to identify the culprit. Validating charging speed. MacBook Pro 14" typically charges at 60–96W; lower numbers point to a weak adapter, a cheap cable, or a thermally throttled charge port.