How to figure out if a MacBook power adapter or battery has gone bad

You plug in your adapter to your laptop, and the battery doesn’t charge reliably. Sometimes, your Mac dings to let you know it’s plugged in to power; other times, you have to plug and unplug, or even restart your computer. What’s up?

Battery charging involves three separate elements, so you have to go through a process of troubleshooting to identify which one is faulty.

The battery

For several releases of macOS, Apple has provided alerts and information about the health and status of a laptop’s battery. macOS warns you if something’s actively wrong with a battery when it determines this.

In macOS Catalina and earlier, you can Option-click the battery icon in the menu bar, and get a little more insight about the state of the battery. In macOS Big Sur, there’s a lot more detail about the battery available by default, but the condition is nested more deeply: go to the Battery preference pane, click Battery, and click Battery Health.

mac911 big sur battery dropdown IDG

Big Sur shows the current battery parameters, but not battery health. Click Battery Preferences for that.

The condition should be listed as Normal, but if the battery’s maximum capacity has dropped below a certain point (which Apple doesn’t specify), it might say Service Battery. You may also see one of a number of other messages that Apple doesn’t document, such as Service Recommended, Replace Soon, or Replace Now, all of which have a little more urgency, as the operating system has deemed the battery holds a charge poorly, or even not at all. If the battery dies entirely, an X appears through the battery icon, and the message reads No Battery Available.

In Big Sur through many earlier releases,  you can hold down the Option key and select  > System Information and click the Power item under Hardware in the left-hand navigation bar. Look for Condition there, where you can also see Cycle Count and, on certain models and versions of macOS, Maximum Capacity. The Cycle Count isn’t the number of times you’ve charged, but rather the total capacity of the battery divided by the total energy every used. The more cycles, the lower total capacity the battery has remaining, though it should be both years and…