Lithium-ion batteries wear fastest when they sit full. Battery University's tables: a battery stored at 100% for a year at room temperature keeps about 80% of its capacity, against 96% at 40%; and charging to about 80% instead of full roughly doubles the number of charge cycles (600 to 1,000 against 300 to 500). A MacBook that lives on its charger sits at 100% most of the day. This free, open source tool stops it at 80%.
Here is what you get, how to set it up, and the catch.
What you get
- Charging stops at 80% and the battery is held there, even while your MacBook stays plugged in.
- If the battery is above 80% when you start, it lets it drain down to 80% while plugged in.
- The limit stays on after a restart, and after you close the menu bar app.
- Want a different number? The command line lets you pick any level or a range, like 70 to 80.
- Need a full battery for a trip? One command charges it to 100% first.
Free, for your email
Get the full setup steps + the copy-paste setup prompt
The rest of this guide (5 more sections) opens right here. The setup prompt, one paste into Claude that sets it all up, comes by email only. Use your real address.
Unlocks: Step 1: check your Mac · Step 2: set it up with Claude · The catch · A prompt to start · Sources
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