Generally speaking, it is safe to leave a MacBook plugged in all the time. A huge number of MacBook usage are in scenarios where a MacBook is sitting on a desk, connected to a charger, and often to an external display, keyboard, and mouse too. These “use a laptop as a desktop” situations are incredibly common in the workplace and school with Apple laptops, and for many home users as well.

When a MacBook is plugged in and charging, it will typically perform at it’s best, since there is no need to engage in energy conservation or battery life extension. It’s not totally unusual for some MacBook users to have discovered their laptop feels like it’s running slower than usual when running on battery particularly when battery life is relatively low, and in fact it often is running slower because of the Low Power Mode feature, which directly throttles performance to extend battery life.

While there’s nothing wrong with keeping a MacBook plugged in all the time, and you’ll often have the best CPU performance by doing so, there are a few things to keep in mind that may contribute to the broader battery health and battery longevity of your MacBook, so it’s important to keep those in mind.

Important considerations for keeping MacBook plugged in

Most modern laptop and gadget batteries are lithium-ion based, including those that are found in MacBooks, which means they degrade over time and with usage. The battery in a MacBook is designed to be used. Keeping a lithium-ion battery at 100% charge constantly may reduce the overall lifespan of a battery, but modern Macs include battery maintenance features that help to prevent this. Nonetheless, it’s still good practice to use your Mac laptop as a laptop from time to time, and let the battery discharge to 20%-30% or so, and then charge it again.

Apple explains the various factors that can contribute to Mac battery health and battery lifespan as follows: “All rechargeable batteries are consumable components that become less effective as they get older—and their age isn’t determined only by time. A battery’s lifespan depends on its chemical age, which is affected by factors such as its temperature history and charging pattern. As your notebook’s battery ages chemically, its charging capacity gets smaller.”

Let’s pay particular attention to the ‘temperature history’ and ‘charging pattern’, because those are both often directly controllable by MacBook users.

Modern versions of MacOS have built-in battery optimization features that aim to extend the lifespan of the devices battery. One of the primary means of doing this is by learning your laptop usage and charging habits, and then delaying the amount of time the MacBook spends fully charged. For example, let’s say you get to your desk every day at 8am, plug in your MacBook, and then leave your desk every day and disconnect the MacBook at 4pm – macOS battery optimization will observe and learn this schedule, and then hold your laptop battery at an 80% charge level until the end of the day, when it will then charge the battery to 100%. Apple Silicon Mac laptop batteries will use fast charging tech to get to 80% capacity, and then they automatically switch over to a slower charging style referred to as ‘trickle charging’, where the remaining 20% will charge much slower, at a defined time, or sometimes not at all.

Battery Optimization is enabled by default on every modern Mac, but you can confirm it is enabled on your particular Mac laptop by going to  Apple menu > System Settings > Battery > Battery Health > clicking the tiny (i) button next to Battery Health make sure “Optimized Battery Charging” is enabled. Battery Optimization should be enabled on Mac laptops for best performance and longevity.

Avoid extreme heat

Extended exposure to high heat or extreme heat can negatively impact battery health and battery life, and it’s also not great for any tech in general. Heat can directly damage lithium-ion batteries. Keep the MacBook Air or MacBook Pro out of direct sunlight, and away from heat sources. Do not smother the laptop, which can prevent heat from dissipating as designed.

Additionally, if you run the MacBook in clamshell mode (meaning closed, but still on and connected to an external display), you will want to make sure it is well ventilated around it, particularly with the modern MacBook Air since it does not include a cooling fan. The fan-less design of the Apple Silicon MacBook Air series makes it a very power efficient and silent computer, but it is known to throttle performance when overheating or in clamshell mode and under heavy usage.

Aside from potential battery issues, high heat will often cause CPU performance to reduce and throttle. If you’ve ever used a MacBook outside in the sun on a warm day, felt the computer get very hot to the touch, and then suddenly become almost unusably slow with beachballs, it’s likely because the Mac is overheating and the system is reducing performance and other activity to try and cool things down. There are a variety of helpful ways to keep a MacBook cool in hot weather and high temperatures if you want more specifics, but a little common sense goes a long way.

Keep macOS updated

It’s important to keep up to date with macOS software updates and install those updates when they are available. Not only do macOS system software updates routinely fix bugs and security issues, they may also address any known issues with energy usage, battery optimization and usage, or other power management related circumstances. You can update macOS by going to  Apple menu > System Settings > General > Software Update.