This Hidden MacBook Feature Tells You Exactly When The Battery Needs Replacing

Contrary to popular belief, you can't recharge lithium-ion batteries an infinite number of times, not even in MacBooks. Sooner or later, you will need to replace the battery in your laptop if not your entire laptop – sooner if you have bad daily habits with your laptop. While there are many warning signs that your battery is about to die, MacBooks can actually tell you how long your battery has left. Or at least estimate it based on the number of power cycles. According to Apple, you can get a good feel of your laptop battery's remaining life in the computer's System Information menu. To access this information:

• Hold down the Option key and click on the Apple menu.
• Select "System Information."
• Open the "Hardware" dropdown menu, and then select "Power."

The information you are looking for is labeled "Cycle Count," underneath "Health Information." This page will also tell you the battery's condition and whether it's losing charge capacity (under "Maximum Capacity").

The "Cycle Count" information is quite simple, as it only provides a number. Apple also provides an exhaustive list of the "Maximum Cycle Count" of every available MacBook model, which is exactly what you think: the maximum number of times you can safely charge the battery. For instance, if you have an M5 Max MacBook Pro (arguably the best model currently available), and your "Cycle Count" is at 126, you've got quite a ways to go until you need to replace your MacBook's battery.

When you hear the word "battery cycle," you might assume it means that every time you charge your battery, it counts as one cycle. However, the chemistry of a rechargeable lithium-ion battery doesn't work that way. Apple states that a battery charge is determined by the amount of power the charger replenishes. Let's say that one day you use 90% of the MacBook's battery and then charge it overnight. That's not one full battery cycle, but 90% of one — not that the System Information menu will tell you. 

However, the next time your laptop runs on battery power and is subsequently plugged in, so long as you use at least 10% of the stored charge, your MacBook will register it as one new battery cycle. While many people might say you shouldn't leave a laptop plugged in all the time, you can, so long as your MacBook is running on macOS Catalina 10.5.5.

This update offers the option to turn on an "optimized battery charging" setting, which caps the battery level at 80%. You will have to charge it more often when you eventually unplug the laptop, but battery cycles won't stack up as quickly because the computer isn't charging to full. Always make sure your MacBook is installing the latest macOS (and fix it if it isn't) to get more helpful updates like this.