Should You Charge Your Smartphone Overnight?

This guide provides a clear, practical overview of should you charge your smartphone overnight?, with useful context, important details, and straightforward takeaways for everyday readers.

What the producer said

Battery life isn't just based on when it's assembled. There are many other factors, including extreme temperature fluctuations and battery charging habits. The lithium-ion batteries in our phones age chemically and charge less over time. That's why old phones don't last for long.

So does overnight charging make a big difference? Apple says that when your iPhone is 'still fully charged for an extended period of time, the battery health may suffer'.

Manufacturers of Android phones, including Samsung, say the same. 'Don't leave your phone connected to the charger for long or overnight,' says Samsung. Meanwhile, Huawei said: 'Keeping the battery level as close to mid-level (30% to 70%) as possible can effectively prolong battery life.' In general, please keep your phone charged, but not fully charged.

The phone's battery will automatically stop charging when it's full, but in some cases, when the battery drops to 99%, the battery will need more power to get back to 100%. This continuous cycle consumes the full life of the battery. Most phones come with specified charging options for this reason.

Use the built-in features on your phone

On iPhones running iOS 13 and above, the Optimized Battery Charging feature helps reduce the time it takes to fully charge your phone. Once turned on, iPhone analyzes your charging habits and waits for the 80% charge to finish until users need it.

Apple and Samsung recommend that you do not let your phone charge for too long or charge overnight as it affects the battery quality. According to Huawei, your battery will last longer when kept at 30-70%.

As such, the important point here is to charge your phone but not to fully charge it.

Some users today still believe that the phone must be 100% fully charged and not be pulled out during the charging process to help the battery last long. This is completely inaccurate.

Usually, the life of today's popular batteries, such as Li-Ion or Li-Polymer, is influenced by the charging cycle.

Unplug the charger when your phone's battery is about 80%.

Specifically, your phone needs to be charged from 0-100% to be counted as one cycle. For example, a phone being charged between 20-100% isn't a cycle yet, as the battery is only 80% charged. As such, you need to charge 20% more the next time to finish.

The capacity of the batteries is only 80% after about 300-500 charging cycles. However, the reality shows that many types of batteries have deteriorated after only 100 cycles.

Current battery technologies have control circuits that automatically disconnect charging when it reaches 100%. However, when you charge overnight, the device can slide down to 99% and continue charging again. This can gradually drain the battery life.

Therefore, make the most of the battery saving features on your phone. The less wear and tear, the longer your battery will last.

Currently, there are many features and technologies to help you save charging time and limit the need to charge overnight. 

If you use an iPhone running iOS 13 or later, turn on the Optimized Battery Charging feature to assist with the charging process. Specifically, the device will record your charging habits and only charge up to 80% and then stop. Then, estimate when you can use your phone again to charge it another 20%.

To check if this feature is turned on, you can go to Settings> Battery> Battery Status.

Apps, such as AccuBattery for Android, can also help you monitor battery health in real time. From there, you will know the right time to charge to maximize battery life.

In addition, there are other ways to keep your battery healthy:

• No need to wait for the battery to drop to 0% to charge. Charge when convenient, and don't worry too much about percentages.
• Keep the phone as cool as possible. Heat affects battery life in the long run, so putting it under a pillow is one of the worst things we can do. The same goes for leaving your phone in the sun or outside in cold weather.
• If you wake up at night and find your phone is fully charged, unplug it. It won't make a big difference, but it certainly won't do any harm.