Feature · 電力
Per-app battery drain.See which apps cost the most.
On the Saga page, Sensei ranks the top power users. Flip between right now (live), the last 3 hours, or 5 days — and toggle each value between percent of a full battery and watts (live draw) or watt-hours (over a window). Each app gets an Activity-Monitor-style energy impact score (CPU time blended with idle wake-ups), an impact label (Low / Moderate / High / Very high), and a search filter so you can find every Chrome helper in the list. History is sampled every 5 minutes; the live Now view refreshes about every 10 seconds. No system extension, no kernel hooks.
Why it matters
Battery loss is almost never the battery's fault. It's a hung helper, a sleepless tab, a video call that won't release the GPU. Knowing which app costs you the most is the difference between a 4-hour day and a 7-hour day.
How the energy impact score works
Activity Monitor calculates an energy impact score per process — a composite of CPU time, idle wake-ups, and a few less-public metrics that influence how much battery a process is actually costing you. It’s the same number macOS uses to flag "apps that draw significant energy" in the battery menu, except surfaced live and rankable.
Sensei pulls this score from per-process resource usage — no system extension, no kernel hooks, no privileged operations. The live Now view refreshes about every 10 seconds (smoothed over the last ~30 seconds) while you’re watching it, so the watts you see track what’s happening right now; the 3h and 5d windows lean on a 5-minute history. The numbers are exactly what Activity Monitor would show if you opened it at the same moment, just gathered continuously so you can see trends.
Each row shows the share of a full battery the app spent, or — one toggle away — an estimate in watts (live draw on Now) or watt-hours (energy consumed over the 3h / 5d windows). Same data, the unit that fits the question.
What to look for
- Background tabs. Browsers are the single biggest category — and within them, a small handful of tabs usually dominate. Search "chrome" or "safari" and watch every helper process line up.
- Hung helpers. An app whose energy score keeps climbing while you’re not using it is the classic signal of a stuck process. Often it’s an analytics or update helper.
- Video calls that won’t let go. Hanging up doesn’t always release the GPU. If your battery drains 20% faster after a meeting than during, the meeting app is still holding context.
Cross-references
When energy impact spikes, the per-cell thermal state usually follows within a few minutes. The two readouts are paired in the menu bar so you can connect cause and effect — see the live watts in / out number for the cleaner version of "how fast is the battery going."
For the deeper question of whether plugged-in or unplugged is better in the first place, see should I keep my MacBook plugged in?
Frequently asked.
- How often does it refresh?
- The live "Now" view resamples about every 10 seconds — smoothed over the last ~30 seconds — and only while that view is open, so you get a current read without spending battery to measure battery. The 3h and 5d history windows are sampled every 5 minutes; Activity Monitor’s energy impact is already a moving average, so finer history wouldn’t show more, just cost more.
- Does this require a system extension or root privileges?
- No. Sensei reads per-process resource usage through standard, sandboxed APIs. No kernel hooks, no special permissions, no privileged operations.