Most MacBook batteries are lithium-ion, which are designed to retain about 80% of their original capacity after 1000 charge cycles, meaning they can last several years with proper usage.
To check battery health on a MacBook running macOS Ventura or later, navigate to System Settings, then select Battery.
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Here, you can see the Battery Health and Maximum Capacity.
The maximum capacity percentage denotes how much of the original capacity the battery can hold; for example, a battery at 80% maximum capacity can only hold 80% of the energy it could when new.
A battery cycle is defined as using 100% of your battery's capacity, but this doesn't need to happen all at once.
For instance, using 50% of the battery one day and recharging it fully, then using 50% again the next day counts as one cycle.
The Battery Condition section in the System Settings will provide terms like "Normal," "Replace Soon," "Replace Now," or "Service Battery," indicating the current health status of the battery.
Holding the Option key while clicking the Apple menu allows you to access the System Information, where you can find detailed battery statistics, including cycle count and health status.
The science behind battery health involves the gradual degradation of the electrolyte and electrodes within lithium-ion batteries, which affects their ability to hold a charge over time.
Temperature plays a crucial role in battery health; extreme heat or cold can accelerate degradation.
Ideally, MacBooks should be used in environments between 50°F and 95°F (10°C to 35°C).
Software settings, such as enabling "Optimized Battery Charging," can help extend battery lifespan by learning your charging habits and reducing the time the battery spends at 100% charge.
A hidden feature in macOS includes a Battery Report, which provides a comprehensive overview of battery health, usage history, and charging patterns, accessible through the System Report.
In macOS, the battery meter can often overestimate remaining battery life, as it does not account for various factors such as temperature, usage patterns, and background applications.
Battery health can also be impacted by how you store your MacBook; if left unused for extended periods, it is recommended to keep the battery charged to about 50% to avoid deep discharge.
Regularly shutting down your MacBook instead of keeping it in sleep mode can help preserve battery health by allowing the battery to recalibrate.
Old batteries may swell due to gas build-up from chemical reactions, a sign that they should be replaced immediately to avoid damage to the MacBook.
The MacBook trackpad can be affected by battery health because a failing battery may cause physical distortion that impacts the trackpad’s sensitivity and functionality.
Apple's macOS includes battery diagnostics which can detect issues and provide recommendations to improve battery health, functioning similarly to how a car's diagnostic system operates.
The design of the MacBook's battery management system includes algorithms that adjust charging rates to optimize battery longevity, similar to how smart thermostats learn user habits for energy efficiency.
Some MacBook users employ third-party applications to monitor battery health, but it is crucial to ensure these apps do not compromise system security or accuracy of the data.
The gradual reduction in battery health affects not just the runtime but can also impact system performance, as macOS may throttle performance to conserve remaining battery life.
Understanding the chemistry of lithium-ion batteries reveals that as the battery cycles through charge and discharge, the formation of lithium plating on the anode can reduce capacity and efficiency, highlighting the importance of proper charging practices.