Your MacBook’s Battery Is Slowly Degrading Because You Skipped One Setting

Your MacBook’s lithium-ion battery starts aging the moment you charge it to 100 percent and leave it there. macOS Tahoe 26.4 introduces a Charge Limit slider that caps your maximum battery level anywhere between 80 and 100 percent, and the difference it makes over two or three years of ownership is dramatic. The catch is that Apple buried this setting behind a tiny info button inside System Settings, and the default behavior still charges straight to full.

I’ve been watching Apple add charge management features to the iPhone since iOS 13, and the MacBook has been conspicuously left out of that conversation until now. Optimized Battery Charging has existed on Macs for a while, but it only delays the final push to 100 percent based on your routine. It never actually stops the charge from hitting the top. Charge Limit is the feature that finally draws a hard line.

Here’s where to find it, what each setting actually does, and why the number you pick matters more than you might expect.

How to Enable the Charge Limit Slider in macOS Tahoe 26.4

Open System Settings, click Battery in the sidebar, and look for the word “Charging” with a small circled “i” icon next to it. Click that icon. A panel slides open with a slider ranging from 80 percent to 100 percent in five-percent increments: 80, 85, 90, 95, or 100.

Set your desired limit, close the panel, and your MacBook will stop charging once it reaches that threshold. That’s it. No restart required, no terminal commands, no third-party apps.

One detail worth knowing: when you drag the slider back up to 100 percent after using a lower limit, macOS asks whether you want to keep it at 100 permanently or just charge to full this one time and revert tomorrow. That’s a thoughtful touch for the “I need a full battery for this flight” scenario without undoing your long-term strategy.

Why 80 Percent Is the Magic Number

Lithium-ion batteries degrade faster at higher charge states. The chemistry is straightforward: when lithium ions pack tightly into the graphite anode near full capacity, the voltage required to push them in rises. Higher voltage generates heat. Heat accelerates chemical aging. According to iFixit’s battery research, charging to 80 percent instead of 100 percent can multiply the total energy a battery delivers over its lifetime by roughly four times.

That number sounds impossibly large until you consider what “lifetime” means here. Apple designs MacBook batteries to retain 80 percent of their original capacity at around 1,000 full charge cycles. If you consistently charge to 80 instead of 100, each cycle puts less stress on the cells, so you reach that 80-percent-of-original-capacity threshold much later. You’re not getting four times more battery per charge. You’re getting four times more useful months out of the battery before it noticeably weakens.

For anyone who keeps their MacBook plugged into a monitor and power adapter for eight or ten hours a day, this matters enormously. Those machines sit at 100 percent for the vast majority of their lives, which is the single worst thing you can do to a lithium-ion cell.

How Charge Limit Differs From Optimized Battery Charging

Optimized Battery Charging is a machine learning feature that has existed on Macs since macOS Catalina. It learns your charging routine and delays the final 20 percent of charging until just before you typically unplug. The idea is smart: if you always unplug at 8 AM, it charges to 80 percent overnight and tops off to 100 right before you leave.

The problem is that it still charges to 100. Every time. It just changes the timing. And if your schedule is unpredictable, the feature often doesn’t engage at all. I found that Optimized Battery Charging required at least 14 days of consistent habits and at least nine charges of five hours or more in the same location before it reliably kicked in. That’s a lot of routine for a feature that’s supposed to be automatic.

Charge Limit is different. It doesn’t learn. It doesn’t predict. It draws a ceiling and enforces it. Set it to 85 percent, and your MacBook will never charge past 85 unless you manually override it. Both features can work together: you can set Charge Limit to 90 and leave Optimized Battery Charging enabled, so the Mac delays even the climb to 90 based on your patterns.

The one caveat Apple documents is that your MacBook will occasionally charge to 100 percent even with a lower limit set, in order to recalibrate the battery’s state-of-charge estimate. This is normal. The battery management system needs an occasional full cycle to report accurate percentages. It happens infrequently enough that it won’t meaningfully affect battery longevity.

What Percentage Should You Actually Choose

This is where most articles stop: “set it to 80 and walk away.” That’s fine advice if your MacBook lives on a desk. But not everyone uses their laptop like a desktop.

For desk-bound MacBooks plugged in most of the day, 80 percent is ideal. You’re sacrificing 20 percent of portable runtime in exchange for significantly slower battery aging. If you only unplug for meetings or to move between rooms, that trade-off is easy to make.

For hybrid users who split time between a desk and mobile work, 85 or 90 percent offers a better balance. You keep enough charge for a few hours of unplugged use without pushing the battery into the high-stress zone above 90.

For frequent travelers who rely on full battery capacity, 95 percent preserves most of the longevity benefit while giving up only 5 percent of total runtime. Even that small reduction in peak charge voltage meaningfully reduces cell stress compared to sitting at 100.

The flexibility here is the whole point. Apple chose five-percent increments for a reason: there’s no single correct answer, and the right limit depends on how you actually use your machine.

Automating Charge Limit With Shortcuts

macOS Tahoe 26.4 also exposes Charge Limit to the Shortcuts app, which opens up some genuinely practical automations. You could build a shortcut that sets the limit to 80 percent when you arrive at your home office and bumps it to 95 when you’re packing for a trip.

The Shortcuts action is called “Set Charge Limit” and accepts any value from 80 to 100 in five-percent steps. Pair it with a time-of-day trigger or a Focus mode automation and you have context-aware battery management without thinking about it.

This is the kind of quiet automation that macOS Tahoe does well. If you’ve been exploring other ways macOS Tahoe streamlines your workflow, our guide to hidden macOS Tahoe settings covers several more buried features worth enabling on day one.

What This Means for Long-Term MacBook Ownership

Battery replacement on a MacBook isn’t cheap. Apple charges between $199 and $249 depending on the model, and the process requires mailing your machine in or visiting an Apple Store. Third-party replacements exist but void any remaining warranty.

Charge Limit doesn’t eliminate battery degradation. Every lithium-ion battery has a finite lifespan regardless of how carefully you treat it. But the difference between a battery that retains 85 percent of its capacity after three years and one that’s down to 75 percent is the difference between a MacBook that still feels responsive and one that sends you a “Service Recommended” warning.

If your MacBook also feels sluggish after the macOS Tahoe update, the battery settings aren’t the only place to look. Our guide to fixing a slow Mac covers the performance side of the equation, from Spotlight reindexing to login items that silently eat resources.

Set the limit, forget about it, and check your battery health in a year. The numbers will speak for themselves.