The newly released macOS 26.4 Tahoe introduces a couple of helpful battery features for MacBook users. There’s now a Slow Charger indicator that lets you know when your charger isn’t delivering enough power, and a new Charge Limit feature that allows you to cap your battery charge anywhere between 80% and 100%.
Both updates are part of Apple’s ongoing effort to extend battery lifespan. Understanding how they work and when to adjust them can help you avoid confusion and get more life out of your MacBook battery.
Why Apple Limits Charging
Battery lifespan is tied to what Apple calls “chemical age,” which is influenced by how often and how long a battery stays fully charged, along with how much heat it generates. Lithium-ion batteries wear down faster when they sit at 100% for long periods or get too warm while charging.
This is especially relevant for MacBooks that spend most of their time plugged in at a desk. Without any limits in place, the battery would stay at 100% constantly, which over time reduces its overall lifespan.
Optimized Battery Charging
Apple’s Optimized Battery Charging uses on-device learning to understand your daily routine. The goal is to have your Mac fully charged right when you need it, not hours before.
If your MacBook is usually plugged in, you might notice it holding at around 80% for a while, then topping off closer to when it expects you to unplug it. When this is happening, you’ll see Charging On Hold in the battery menu.
This same idea exists on iPhone, iPad, and Apple Watch, where devices learn when you typically disconnect from power and delay charging past 80% until just before that time.
The New Charge Limit Feature
The new Charge Limit setting gives you more direct control. Instead of relying on predictions, you can choose exactly how high your battery charges.
You can set a limit between 80% and 100% in System Settings > Battery, then click the ⓘ next to Charging. Once set, your Mac will stop charging once it reaches that level and only resume if the battery drops a few percentage points below it.
This is especially useful if your MacBook rarely leaves your desk. Keeping it at 80% can significantly reduce long-term battery wear while still leaving you with enough charge for short periods away from power.
When You Need a Full Charge
There are still times when you’ll want a full 100% charge, like before a long travel day or when you’re not sure when you’ll have access to power. You can override these settings when needed:
- For immediate use: Click the battery icon in the menu bar and choose Charge to Full Now
- To temporarily disable limits: Go to System Settings > Battery, click the ⓘ next to Charging, turn off Optimized Battery Charging, and choose Turn Off Until Tomorrow. Set Charge Limit to 100%
- To disable permanently: Follow the same steps, but choose Turn Off instead. Keep in mind this will reduce long-term battery health
Similar options are available on iPhone and Apple Watch if you want more control there as well.
About That Slow Charger Warning
The new Slow Charger alert helps explain why your Mac might be charging slowly or even losing battery while plugged in. If your charger isn’t providing enough power for your Mac model, you’ll now see a warning in the battery menu and in System Settings.
You can check your charger’s wattage by looking at the adapter itself or by opening System Information and checking the Power section. It’s fine to use a higher-wattage charger than required, but going below the recommended wattage can cause issues.
For optimal charging, use an adapter that delivers at least the minimum wattage recommended for your Mac:
- MacBook Neo: 20 watts (no fast charging available)
- 13-inch MacBook Air: 30 or 35 watts standard, 67 watts for fast charging
- 15-inch MacBook Air: 35 watts standard, 70 watts for fast charging
- 14-inch MacBook Pro: 70 watts standard (or 96 watts for M4 Pro and M4 Max chips); 96 watts for fast charging
- 16-inch MacBook Pro: 140 watts for both standard and fast charging
Using your iPhone’s 20W charger with a MacBook Pro might technically work, but you’ll now be warned that it’s not delivering adequate power.
Finding the Right Balance
Apple’s battery features are all about balancing convenience with long-term battery health. For most people, leaving Optimized Battery Charging on is the easiest path, since it adjusts automatically based on your habits.
If your routine is less predictable, or your Mac stays plugged in most of the time, the new Charge Limit gives you a simple way to take more control.
Either way, it’s helpful to remember that keeping your battery at 100% all the time will wear it down faster. Whether that trade-off matters depends on how you use your Mac and how long you plan to keep it. If you’re not sure how your MacBook is currently set up or want help finding the right balance, feel free to reach out. We’re happy to take a look with you.
(Featured image by iStock.com/shirophoto)
