Does charging the phone all day shorten battery life or is it better to empty it permanently?

Some people connect their phone to the charger when power is available, while others maintain the battery level accurately between 40% and 8...

Some people connect their phone to the charger when power is available, while others maintain the battery level accurately between 40% and 80%, driven by the belief that battery life will last longer. Is charging the phone all day is really that bad?

If you are not sure about the "correct" way to ship, or if you fear that charging your phone throughout the day may damage its battery, we review the benefits and harms of both methods in this report.

Charge your phone all day

What does science think?

Experts say charging your battery results in reduced performance over time, regardless of how you ship.

Smartphones derive their energy from lithium-ion batteries, which operate by moving carriers (lithium ions in this case) from one electrode to another. The ions move in one direction during shipping, and in another direction during discharge.

Moving these ions increases the voltage on the electrodes and reduces battery life, according to Signify (or philips lighting formerly) chief scientist Hans de Vries and co-author of a research paper entitled "Increasing the life cycle of lithium-ion cells by a partial charging cycle."

"Lithium ion needs some space in the electrodes, and the poles need to save that space," de Vries told the New York Times. As a result of the effort, the condition of the electrodes is gradually deteriorating, also resulting in a loss of battery capacity."

This is exactly the right thing to do when you charge your phone's battery extra in order to get the last few percentage points in the charging level up to 100%. 

IFixit, which teaches people how to fix common electronics and other household appliances, suggested the analogy of sponges.

"It is very easy to fill a sponge with water from drought to saturation," he said. But trying to force the semi-water-saturated sponge to absorb the last dropof liquid requires pressure and is likely to leave more liquid assembled on the surface. This meeting consists of the accumulation (solid electrolyte interface) above the battery. This build-up reduces the total battery capacity.""

So charging the phone's battery to full capacity a few times, and not allowing it to fully unload, can increase battery life somewhat. Putting less effort on the electrodes reduces battery degradation and increases its capacity for longer.

That's one of the reasons why Apple offers improved battery charging on iPhone phones, keeping the battery level below 80% until it needs to be charged again. 

Android phones don't have the same system-wide algorithm, but some phone makers like OnePlus and Asus have offered their own features to improve battery charging.

Heat is another negative factor affecting battery life. 

According to battery university's U.S. website: "Heat is the worst enemy of batteries. Lithium ions perform well at high temperatures, but prolonged exposure to heat reduces battery life."

Heat is also a big problem, especially when using wireless charging.

The site added: "Depending on a number of factors, such as the alignment and quality of the charging base, and the phone cover, the charger can end up connecting half the current it attracts to your phone only. The heat appears when the current meets the resistance."

However, wireless charging standards reject these concerns.

"We're not aware of any negative impact of extended wireless charging," said Wireless Power Consortium founder and president, the entity responsible for maintaining mino telecommunications standards. Our standard standards allow the phone to switch the charger to standby when the phone's battery is full.""

Tevers also suggested that frequent charges, common in the case of wireless charging, may actually increase battery life.

He said: "According to the research we have seen, battery life actually increases by four times when the discharge depth - or the amount of battery consumption - is reduced at 50% instead of 100%. In other words, it can be said that continuing to charge the battery up to 100% during the day, as in the case of wireless charging, and not allowing your phone's charging level to fall below 50%, will actually increase battery life.""

What do manufacturers think?

Major phone manufacturers have refused to provide any recommendations on specific charging mechanisms when asked, but they offer some vague advice on their websites:

Apple advises: "You should charge the iPhone's lithium battery whenever you want. There is no need to leave the battery completely empty before recharging." On another page of Apple's website, the company points out that extremely high temperatures (or above 35°C) should be avoided, as well as removing the phone's cover that may cause the phone to overheat during charging.

Google recommends: "The phone can be charged as much as needed. There's no need to notify your phone of the size of your battery capacity by charging it from zero to 100% and letting the battery run out from 100% to zero.""

Samsung recommends charging the battery regularly and keeping it above 50%. The company also says charging the phone after it reaches 100% may reduce battery life.

If charging your phone all day affects battery life, will you notice?

Charging your phone all day and letting the battery completely empty are habits that are likely to erode battery life. But is the effect big enough to make a difference before upgrading your phone to a new version?

Data indicate that phone replacement cycles are longer and do not fall short. A 2019 study found that Americans now keep their smartphones for an average of about three years. IPhone users can keep their phones for as long as four years, according to one analyst.

If you don't buy a new phone regularly and don't follow ideal charging practices, these are logical reasons why your phone's battery life will decline over time. But other factors, such as how much your phone is generally used, are more likely to have a greater impact on battery life than charging behavior. 

This is because lithium-ion batteries are classified by the number of specific charging cycles, or up to 100% of the charge. (These cycles are cumulative, so charging the phone twice from 50% to 100% is counted as a single charging cycle.) The more you use your phone, the more you have to recharge the battery, which consumes it the more.

Losing 15% of your phone's battery capacity over two years is noticeable, of course, but it leaves you enough space to allow most people to pass the day without having to recharge it – especially with the huge batteries on the new iPhone. 

For phone users who consume their batteries more quickly, or those with older phones with smaller batteries, the good news is that batteries can be replaced at a relatively cheap price. 

Apple has set $50 to $70 to replace the battery, according to the iPhone model, while Samsung's Galaxy phone batteries are only $50. 

UBreakiFix, Google's partner for immediate pixel repair, charges between $80 and $110 for battery replacement.

It depends on what suits you in the end.

In the long run, you should choose what's best for you: take care of your battery to prolong its life, or charge it whenever you want to keep your phone ready when needed.

It may be better to allow the phone's battery to lose its charge gradually, then recharge it when needed up to 80%, and in return of course some people will not want to risk getting out of the house with an uncharged phone, so it depends on the circumstances!