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Overheating and Overcharging Phone’s Battery Life Explained

Overheating and Overcharging Phone’s Battery Life Explained

When anyone thinks about buying a new smartphone, the battery life is usually a very important factor to consider. As we spend so much time on our phones, it is obvious that we expect more from them to last longer. Alongside screen size and camera quality, an all-day charge has become a critical feature for users.

Now that our devices increasingly get more sophisticated, features such as data-consuming apps and high-quality screens use so much battery power. This growing demand for better battery life has led to the emergence of fast chargers, which can be found in all high-end devices.

Premium phones like the Samsung Galaxy S20 and iPhone 11 have the fast and most power-delivering battery life. If the battery drains before the end of the day, one can quickly recharge it using a lightning-fast quick charge. Luckily, with fast-charging, a 10-minute charge can make a huge difference as opposed to turning on the power-saving mode and losing more power even before you know it.

Smartphones are now putting more effort to incorporate the fast-charging feature even in the mid-range phones. There has been worries and questions about the effectiveness of high-capacity chargers. Do they damage the phone’s battery in the short term? What causes unnecessary wear and tear on the battery anyway?

Smartphone Batteries

All mobile phones, electric vehicles and some electronic devices use lithium-ion (Li-ion) rechargeable batteries. It’s quite difficult to create batteries that last longer because battery technology hasn’t changed in decades. The only improvement in battery life has been from power-saving features built into devices and from making the software that mitigates the charging and discharging.

The focus has shifted from mobile phones to extend the battery life of devices that need more than two or three years of functionality. These include cars, satellites and sophisticated home power systems. Besides, compared to car batteries, a phone’s power source is quite minimal. For instance, Tesla 3’s rechargeable battery has a battery capacity of over 4,000 times greater than the iPhone 11 Pro Max.

Larger phones with a huge battery capacity can run all day from a single 100% charge. While that lets the battery last for a great amount of time between charges, the higher voltage needed to top it off puts the battery under more stress.

Fast Charging Doesn’t Damage the Smartphone Battery

A standard charger has an output of 5 to 10 watts. A faster charger can improve that by up to eight times. Unless there’s some technical flaw with your battery or charger, a fast charger won’t do your phone’s battery any long-term damage.

Fast charging batteries function in two stages. The first provides a blast of voltage to the empty or nearly-empty battery. This gives that blazing charge of 50-70% in the first 10, 15 or 30 minutes. This is attributed to the fact that batteries can absorb a charge quickly without major negative effects on their long-term health.

The second stage is where the technology has to slow down and carefully manage the charging speed or else the charging process could actually damage the battery. Arthur Shi, a tear-down engineer at iFixit, gave an analogy and suggested that a battery acts like a sponge. When you pour water onto a dry sponge, it absorbs liquid quickly. For a battery, this is the fast-charging stage.

As you keep pouring water onto the increasingly wet sponge at the same rate, the liquid will sip to the surface as it struggles to soak into the saturated sponge. For a battery, this unabsorbed charge can lead to shorts and other issues that could potentially damage the battery.

A battery’s management system is designed to meticulously monitor the two charge stages and drop the charging speed in the second phase to give the battery time to absorb the charge and avoid issues. This is why it takes 10 minutes to get those last few percentage points.

A Phone Can’t Be Overcharged

People used to have anxiety leaving their phones constantly charging the battery beyond its capacity. Consequently, it could make it unstable, degrade the overall battery life, or even burst into flames. However, a battery’s management system is designed to shut off the electrical charge once a battery reaches 100% before it can overcharge.

Unless the battery circuitry is faulty, you can’t overcharge a modern smartphone. According to Venkat Srinivasan, a battery researcher at the Argonne National Laboratory and director of the Argonne Collaborative Centre for Energy Storage Science, they have protection built into it to stop that from happening.

Therefore, a battery can be put under strain as it nears the 100% mark. It’s the reason why electronic-vehicle makers cut off the charge on new batteries around the 80% mark.

Don’t Let Your Battery Drain to Zero

Discharging a battery all the way down can cause chemical reactions that shorten a battery’s life over time. To avoid a complete discharge, a battery’s management system includes safety features that power down a phone when it reaches an energy level safely above empty. One might think the phone hits zero when they see that last low-battery warning but it isn’t the case. It’s always better to plug in your phone when the battery is around 30%.

High Temperatures Can Damage Your Phone

Heat temperatures always reduce a battery’s lifespan over time. Keep your phone out of the strong sun, away from window sills and off the dashboard of your car to prevent overheating. This can make the battery less efficient over time. In extreme cases, an overheated battery could explode.

“Temperatures as high as 86 degrees Fahrenheit (30C) can decrease a battery’s effectiveness,” said Isidor Buchmann, founder and CEO of battery-technology company Cadex Electronics and its companion Battery University education website.


To get more life out of your battery, you can use the usual energy-saving tricks to conserve a battery’s power. This includes dimming the display’s brightness, turning off Wi-Fi and Bluetooth when not using them, restricting background data usage, and managing apps that use GPS.