Lithium-ion batteries age fastest when held at a high charge in heat. If your MacBook lives on a charger, capping the charge is the single most effective thing you can do for its long-term health.
The “80% rule,” briefly
Keeping the battery roughly between 20% and 80% — and cool — minimizes stress. You don’t need to obsess; the big win is simply not parking at 100% all day, every day.
What macOS does on its own
macOS includes Optimized Battery Charging (System Settings → Battery → Battery Health). It learns your routine, holds around 80%, and finishes to 100% shortly before you normally unplug. It’s on by default and genuinely helps — if you sometimes see “Not Charging” while plugged in, this is often why.
What macOS doesn’t do
There’s no built-in setting for a fixed cap (e.g., “never charge past 80%”). Optimized charging is adaptive, not a hard limit, and it won’t help if your schedule is irregular.
How to set a real limit
A charge-limiting app can hold the battery at a level you choose and let you top up to 100% when you need full runtime. Mac 4 Breakfast includes charge limiting and “sailing” (discharge to a target) alongside health and insights — so you’re not running a separate limiter app on top of a separate health app. It also tracks cycle count so you can see the payoff over time.