Leaving a laptop plugged in permanently can impact the battery's lifespan, according to several reports. While modern laptops are designed to stop charging once the battery is full, the main issue is not overcharging but the gradual degradation of the battery over time. This degradation happens in two ways: through repeated use (known as cyclic aging) and through the passage of time, even when the battery is not being used (known as calendar aging). Calendar aging is influenced by the battery's charge level and temperature. Keeping a laptop at 100% charge for long periods, especially in a warm environment, can speed up this process. Lithium-ion batteries, which are commonly used in laptops, can experience chemical reactions when kept at their maximum voltage for extended periods. These reactions can reduce the amount of usable lithium in the battery and damage the connections between the electrodes and the electrolyte. This can lead to a loss of capacity even if the battery is not used. For example, a battery stored for a year at 40 °C while remaining fully charged can lose about 35% of its capacity, but if it is only 40% charged, the loss drops to about 15%. Laptops that are always plugged in without a charge limit often stay at 100% charge. This, combined with the heat generated by the processor and graphics card, can significantly speed up battery degradation. Heat from the laptop's internal components can reach the battery, especially if the laptop is placed on a soft surface that blocks its vents, which are designed to release heat. To slow down this degradation, limiting the charge to 80% or even 60% can help by keeping the battery cells at a lower voltage. Many laptop manufacturers, including Lenovo, ASUS, Dell, HP, Microsoft Surface, Acer, and MSI, offer options on some of their models to set charge limits or manage battery usage. Apple's macOS Tahoe 26.4, released on March 24, 2026, includes a feature in the battery settings that allows users to set a charge limit between 80 and 100% for MacBooks with Apple Silicon chips. For older Mac models with Intel chips, the AlDente application can be used to set a lower charge limit. Other habits can help complement these settings. For example, recharging the battery when it reaches around 20% rather than waiting until it hits 0% can help maintain its health. Keeping the laptop's vents clear and allowing the battery to sit around 50% before long-term storage can also be beneficial. A full charge can be used the day before a trip to recalibrate an inaccurate battery gauge, even if it is not necessary for battery maintenance.