After three years an M2 MacBook Air sat at 89% battery health. Not a crisis. Enough to ask whether leaving it on the charger at 100% all day was the whole story. Lithium-ion cells age faster at the top of the range. Apple’s Optimized Charging is supposed to help. It is also a black box. I wanted a number I set, not a guess.
Two different jobs get mashed together in this category: capping charge, and reading health. Most “battery menu bar apps” only do the second.
Battery Toolkit — the cap
Battery Toolkit (Free, open-source) is the control I actually use. Apple Silicon only. Maximum charge (floor 50%) and a discharge floor (20%). It can disable the adapter in software so you can force a cycle without yanking the cable.
Install is the unpolished part: brew tap mhaeuser/mhaeuser && brew install battery-toolkit, allow an unsigned helper, turn off Optimized Charging in System Settings. After that it sits in the menu bar and holds the line. I run 80% max, 40% min on a desk-bound Air.
AlDente is the commercial version of the same idea — nicer UI, freemium. It is not in this directory. If unsigned GitHub tools are a non-starter, that is the other door. coconutBattery covers health history on older macOS if Bettery’s 15.2 floor is too new.
Bettery — the readout, not the cap
Bettery ($9.99) puts percentage in the icon and, on click, watts, temperature, cycle count, and health. History graphs whether the 80% cap is doing anything or you are optimizing a rounding error.
It does not limit charging. Pair it with Battery Toolkit or ignore the graphs. macOS 15.2 required.
Battery Buddy (Free) replaces the system icon with emoji so the red low-battery tint is not in your face. Fun, not a charge limiter.
What I would not do
I would not install three monitoring apps and skip the cap. Optimized Charging is fine if you never think about this. If the machine lives on a desk, a hard 80% is the only control that matches the chemistry. Whether it saves a replacement in year five is still a bet. Sitting at 100% for years is the worse bet.