Does Charging Your Phone Overnight Ruin the Battery?

Does Charging Your Phone Overnight Ruin the Battery
Photo by Tyler Lastovich

From performance to features, nearly every aspect of contemporary smartphones exceeds our expectations. Long smartphone battery life and charging are, however, two features that require your attention and cannot be taken for granted. Similarly, you may have heard that charging your phone for extended periods of time may result in overcharging and may cause the battery to degrade faster than expected. But the question is, are these concerns valid or just another myth? Plus, how much ruin do you cause your phone battery by leaving it charging overnight

Let’s go over this bit by bit.

Does Charging Your Phone Overnight Ruin the Battery: Short Answer

The most prevalent misconception regarding overnight charging is that it can overcharge your battery. This simply is not the case.

All smartphones are manufactured with safeguards that prevent the battery from overcharging once fully charged. Once the battery reaches 100 per cent, charging stops. Your device now operates on AC power rather than battery power. Eventually, whether or not you use your phone, the battery will deplete to 99%. At this point, your phone will “trickle-charge”, as the charger repeatedly brings it back up to 100% again. This process does not degrade the battery more quickly than normal use.

Never plug your phone in when the temperature is excessively hot or cold.

Is It Bad to Charge Your Smartphone Overnight?

No, it is not dangerous to charge your phone overnight, as modern electronic devices are equipped with numerous failsafes. To maintain the long-term health of your battery, we recommend using features like Adaptive Charging that delay or slow down overnight charging. To comprehend why, let’s begin with the fundamentals of how a smartphone’s battery operates.

When you discharge the lithium-ion battery in your smartphone, positively charged ions move from the anode to the cathode. Emptying the battery signifies that all ions have been transferred (or spent). When a battery is charged, a similar transfer of ions occurs, but in the opposite direction. However, your smartphone’s battery doesn’t pull current directly from a wall adapter to accomplish this.

Between the charging port and battery, power management integrated circuits (PMICs) are present in the majority of contemporary electronic devices, including every smartphone. These miniature electronic devices regulate the rate and flow of the battery’s current. In order to reduce strain (and consequently, wear) on the battery, the amount of power your phone consumes decreases over time. In addition, once the battery is fully charged, the phone’s circuitry will intelligently cease drawing power from the wall adapter.

That’s right — if you keep your phone plugged in at 100% charge, it simply won’t charge anymore. Instead, it will sip power from the battery until it reaches approximately 99% capacity. The preceding cycle will continue until you unplug the device. Simply put, you can safely charge your devices overnight without worrying about internal damage.

When their batteries reach full charge, modern electronics automatically cease to draw power. However, charging your smartphone to its maximum capacity every time is not ideal for battery life.

The Disadvantages & What You Should Know

While it is unlikely that you will ever overcharge your smartphone’s battery, there are disadvantages to leaving it plugged in overnight that you should be aware of. The consensus in the electronics industry is that lithium-ion batteries last longest when charged between 20 and 80 per cent. This is a rather narrow range; if you strictly adhere to this recommendation, you will only receive about half of your device’s already limited battery life.

However, you can simply attempt to prevent it from reaching either extreme. In other words, prevent your smartphone’s battery from reaching 0% by topping it off before the end of the day.

Despite this, manufacturers subtly discourage you from fully charging your device’s battery. Numerous smartphones report a full charge well before they stop drawing power from the wall, according to our tests. Android skins like One UI also offer a maximum charge limit (like 80%) to prolong the battery’s life.

The True Threat: Heat

Your battery is not harmed by overnight charging in and of itself. However, temperature is a significant issue. Extreme heat or cold is one of the most destructive factors that can affect a battery. Apple has stated publicly that temperatures exceeding 35 degrees Celsius can cause permanent battery damage. This includes internal temperatures as well as external conditions. If your device lacks adequate ventilation, it can easily overheat.

This is the risk associated with overnight charging. Since trickle-charging consumes energy and generates some heat, your phone may overheat if it remains on the charger overnight and cannot dissipate enough heat. This occurs when a phone is wrapped in a blanket or placed beneath a pillow. If you charge overnight, the best thing you can do is ensure the device is placed in the open air or on a heat-sinking material. Alternatively, try a smart power outlet that automatically turns off after a set time.

How to Charge Your Device Without Damaging Its Battery

As earlier mentioned, heat is a major factor known to reduce the lifespan of lithium-ion batteries. Consequently, ensure that your smartphone is charged in a cool and well-ventilated area. Putting it between two pillows, for instance, could cause overheating, a slower charge rate, and a shorter battery life. Wireless charging, while convenient, generates a great deal of heat, so use it sparingly if you want your battery to last as long as possible.

Heat accelerates battery deterioration, so consider disabling fast charging overnight or employing a slower adapter.

In general, rapid smartphone charging increases heat output. In this regard, it may be advantageous to switch to a slower bedside adapter that charges at 5 or 10 watts. That is still sufficient for waking up to a fully charged smartphone. If you own a recent Google Pixel smartphone, your phone will automatically charge slower than the maximum speed at night thanks to the exclusive Adaptive Charging feature. This may, however, only work if your alarm is set between 3 AM and 10 AM.

However, your device already has many built-in safeguards to extend its lifespan. For instance, Samsung asserts that its smartphones’ batteries can retain up to 95% of their total capacity after two years. This is likely why the company is one of the most conservative in terms of faster charging tech.

Even if the battery health of your smartphone declines, there are replacement options available. Depending on the manufacturer, you can replace your smartphone’s battery for anywhere between $40 and $100, all-inclusive. While that is a respectable amount of money, it is arguably considerably less than the cost of a brand-new smartphone. Moreover, you no longer have to worry about plugging in overnight or whenever it is convenient.

What happens if you keep charging your phone after 100%?

If you continue to charge your phone past the 100% mark, it will automatically stop until the battery falls to 99%. The process continues as long as the phone is plugged in and prevents overcharging from occurring.

Is it Safe to charge my phone overnight?

Yes, modern smartphones and batteries can withstand overnight charging. However, it’s generally recommended to use slower charging at night to preserve battery health.

What is the optimal charge percentage for your phone?

The smartphone battery will last the longest if its charge remains between 20 and 80 per cent as much as possible.

Does Charging Your Phone Overnight Ruin the Battery: References

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