For years, the myth has persisted that plugging your smartphone in to charge while you sleep will harm the phone's battery. Though many people do it anyway, others warn that charging a phone that is already fully charged will waste its battery's capacity.

But while those fears may have made sense with the batteries of years ago, they're overblown today.

"Having your phone plugged in at night doesn't diminish the battery," says Kyle Wiens, the head of iFixit, a California company known for its repair guides and "teardowns" of consumer gadgets. "It's all about cycle count.

Smartphones rely on lithium-ion batteries. Battery cells have two electrodes, one electrode is graphite and the other is lithium cobalt oxide, and there’s a liquid electrolyte in between which allows the lithium ions to move between the electrodes. When you charge they go from positive (lithium cobalt oxide) to negative (graphite), and when you discharge they move in the opposite direction.

Batteries are typically rated in cycles, the cycle count is the number of full charges a smartphone can deal with before its battery is significantly degraded. For example, the iPhone battery is supposed to retain 80% of its original capacity after 500 complete cycles. A charge cycle is simply defined as using up 100% of your battery’s capacity, though not necessarily in one go from 100 to zero; it could be that you use 60% one day, then charge your phone up overnight, and then use another 40% the next day to complete a cycle.

The typical smartphone battery will get about 400/500 charge cycles, which should help the device last at least a year and a half. It's not uncommon for some to last beyond that. That's about as long as many people keep their devices anyway. But leaving your phone in the charger overnight, even when it's fully charged, won't do much to change how frequently its battery runs through cycles, which are drained by simply using the phone.

"In terms of the gradual erosion of battery life, what must be understood is that phone batteries are constantly in a state of decay," a representative for the battery and charger accessories maker Anker says. "Sleeping with a phone charging overnight will make no noticeable difference in the process."
Degradation occurs over time, and eventually, batteries will fail to hold a charge, but how quickly a battery degrades depends on several factors. You can minimize degradation by treating your battery right.
With the right software, charger, and charging method, you can easily optimize your device’s battery life.

What impacts a battery’s lifespan?

“The lifetime is very much dependent on the resistance or impedance growth inside the battery,” Yang Shao-Horn, W. M. Keck Professor of Energy at Massachusetts Institute of Technology, told Digital Trends. “Keeping the battery fully charged essentially increases the rate of some of the parasitic reactions, which translates to potentially high impedance and greater impedance growth over time.”

The same is true of fully discharging your battery. Essentially, it speeds up the reactions inside, which makes it degrade faster. But fully charging or discharging your battery is far from the only thing to consider.

“There are so many other factors influencing the cycle life,” Shao-Horn said. “If you increase the temperature, for example, you also increase the parasitic reaction rates.”

Too much heat is a major problem because overheating can cause the liquid electrolyte to break down and speed up degradation. You should try to keep your smartphone cool whenever possible, so never leave it on the dashboard in a hot car. It’s also a bad idea to use your phone while it’s charging because it will increase the heat generated. If you are going to charge overnight, then consider switching your phone off before plugging it in to reduce the stress on the battery.

Another factor that could potentially have a negative impact on battery lifespan is the speed of charging. There are a lot of different fast-charging standards now, but there may be a cost for the convenience of fast charging. “Generally speaking, if we increase charging speed and go faster and faster with charging it will reduce the lifetime of batteries,” Shao-Horn said. Though, she said this is likely more of an issue for electric vehicles and hybrids, which require far more power than phones.

“You won’t be able to overcharge or over-discharge a cell,” Daniel Abraham, senior scientist at the Argonne Laboratory, told Digital Trends for a previous article about the impact of wireless charging on battery health.

This idea of fully charging or discharging your smartphone battery is complicated by the fact that manufacturers set the cut off points. They decide what fully charged or empty means and they carefully control how far you can charge or drain your battery. While modern mobile devices are equipped with the ability to not overcharge or overheat, there is a downside to leaving your phone connected to your charger for too long.

Avoiding ‘Trickle Charges’, as most modern phones are equipped with lithium-ion batteries and charging capabilities that are more efficient than regular rechargeable batteries. This means that once they reach 100%, your charger will stop fueling your device. However, if you leave your phone charged overnight, the battery will start to discharge again and when it drops below a specific threshold set by the manufacturer it will charge back up resulting in trickle charges that ensures your phone stays at 100%, by so doing you are also prolonging the time that the battery is fully charged, which is potentially speeding up its degradation. How big an impact that has is very hard to quantify and it will differ from phone to phone because manufacturers handle power management differently and employ different hardware. Constantly charging your phone over the course of hours slowly reduces battery life capacity, so it's wise to avoid this practice as having a high voltage will stress the battery unnecessarily.

“The quality of the materials used makes a big difference to how long the battery lasts,” Abraham said. “You may end up getting what you pay for.”
You also shouldn’t wait until your device reaches 0% to charge because that can harm the battery. Also, consider replacing your phone every few years to avoid dealing with these issues. if you’re on a tight budget and can’t afford to buy a phone that frequently, the right charging practices can add mileage to your current phone.

Choose the Right Adapter and Charger
When shopping for a charger, you can learn a lot about how it will affect your phone based on the amp rating. Charging your phone as little as possible is going to result in the longest battery lifespan.
The ideal rating is 5.0V->1A, which refers to how quickly your phone will charge; higher amp ratings charge faster, while lower ones charge slower. With a 1A charger, your phone will charge at the optimal speed to help keep your battery life strong in the long term.

The general consensus is that you should aim to keep your smartphone battery between 20% and 80%, so a couple of tops up throughout the day are likely better for battery longevity than overnight charging. It may also be prudent to employ fast charging sparingly. A couple of good wireless chargers at home and work could be the ideal solution.

Get Performance-Enhancing Software
Finally, the right app can ensure that your phone fires on all cylinders. With some applications, you can monitor how your phones charge and know when to disconnect, some even can display your battery health and temperature.


While it’s not ideal if you want your battery to last as long as possible, you can leave your phone plugged into the charger overnight without too much risk, provided it’s not a counterfeit charger, and you don’t let your phone overheat. For best results with your smartphone charging, here’s what to remember:

1). Always use official chargers and cables, or certified alternatives from reputable brands and retailers.

2). Don’t let your phone get too hot. Remove the case when charging overnight.

3). For the longest battery life possible, try to keep your battery between 20% and 80%.

4). Avoid letting your phone battery completely discharge.

5). If you can’t turn your phone off while it charges, consider flight mode, or at the very least don’t play a graphically-demanding game while it’s plugged in.

6). Only use fast charging when it’s really needed.

Sources.:

https://www.google.com/amp/s/www.businessinsider.com/safe-charge-smartphone-overnight-2017-8%3famp

https://www.google.com/amp/s/www.digitaltrends.com/mobile/expert-advice-on-how-to-avoid-destroying-your-phones-battery/%3famp

https://www.psafe.com/en/blog/avoid-overcharging-that-precious-phone/

Thanks for sharing this information

Thanks for this

thanks op, I have always knew this fast charge might have an adverse effect on the battery life......


thanks for the eye opener

nice information

Interesting

Some devices like ROG 2, black shark 3 and Xperia 1 II got a feature that allows you to charge your device overnight without actually harming the battery cells...

nic einfo, i am guilty of this cos many a times i leave my camon device to sleep over charging which is not really good.

Thanks for the info

KrazyDave16:
Some devices like ROG 2, black shark 3 and Xperia 1 II got a feature that allows you to charge your device overnight without actually harming the battery cells...

Actually when your phone is fully charged, it stops charging. Power adapters and smartphones have perfected overcharge prevention for years now. If your device has a notification LED you'd notice it goes off at 100 and your adapter even when plugged in becomes cool.

festwiz:


Actually when your phone is fully charged, it stops charging. Power adapters and smartphones have perfected overcharge prevention for years now. If your device has a notification LED you'd notice it goes off at 100 and your adapter even when plugged in becomes cool.

True that.
Earlier point was in reference to OP post saying fast charging is also bad, so I pointed out a few devices I know that allow its users to charge at good ol 5W overnight, especially the Xperia 1 II that got a neat feature that's same as using your laptop plugged in without the batteries if one uses the device while charging.

Nice info for those that took time to read....so in other words it does not affect the battery abi

U should have just said so and just gave us few lines...I for believe instead of writing this epistle.

Good luck