Does Leaving Your Phone Plugged In Ruin the Battery? Apple, Samsung and Google Weigh In

Nobody wants to let their phone run out of juice, but have you been afraid of overcharging your phone? Here's the truth; modern smartphones are no longer in danger from being plugged in even when the battery reads at 100%. This means it's perfectly safe to leave your Android or iPhone plugged in overnight without worrying about destroying the battery in the process. But to be clear: Just because it is safe does not mean it is optimal. While you cannot technically "overcharge" a battery, keeping a lithium-ion cell pinned at 100% creates voltage stress, and the heat generated from sitting on a charger is the real, silent enemy of longevity. Watch this: Physical AI vs. Generative AI: Waymo Battles ChatGPT 09:53 It isn't about immediate damage but rather how fast your battery ages over time. Understanding the difference between what will and won't break your phone is key. Here is the truth about your charging habits. Don't miss any of our unbiased tech content and lab-based reviews. Add CNET as a preferred Google source. The science behind battery wear Battery health is not just about how many times you charge your phone. It is also about how it manages voltage, temperature and maintenance. Lithium-ion batteries age fastest when they are exposed to extreme levels: 0% and 100%. Keeping these batteries near full charge for long stretches of time puts additional voltage stress on the cathode and electrolyte. This is why many devices use "trickle charging" or temporarily pause at 100%, topping up only when needed. Still, the biggest threat is not overcharging, but heat. When your phone is plugged in and running demanding apps, it produces heat that accelerates chemical wear inside the battery. If you are gaming, streaming or charging on a hot day, that extra warmth does far more harm than leaving the cable plugged in overnight. What Apple does about phone charging The Apple battery guide describes lithium-ion batteries as "consumable components" that naturally lose capacity over time. To slow that decline, iPhones use Optimized Battery Charging , which learns your daily routine and pauses charging at about 80% until just before you typically unplug, reducing time spent at high voltage. Apple also advises keeping devices between 0 to 35 degrees Celsius (32 to 95 degrees Fahrenheit) and removing certain cases while charging to improve heat dissipation. You can read more on the official Apple battery support page. What Samsung (and other Android makers) do Samsung offers a similar feature called Battery Protect , found in the One UI battery and device care settings. When enabled, it caps charging at 85%, which helps reduce stress during long charging sessions. Other Android makers like Google, OnePlus and Xiaomi include comparable options — often called Adaptive Charging , Optimized Charging or Battery Care — that dynamically slow power delivery or limit charge based on your habits. These systems make it safe to leave your phone plugged in for extended periods without fear of overcharging. Samsung battery protection support...

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