“I never leave my phone on the charger all night.” It’s a phrase that is frequently heard and doesn’t have a real justification. Even in 2023, myths persist that affect the nickel-cadmium batteries used in early mobile phones. And we’re talking about the 1990s. In those devices, batteries suffered from the dreaded “memory effect,” where the phone would lose charging capacity if it wasn’t fully charged.
Many years have passed, but this fear persists among many mobile phone owners, who continue to respect charging cycles and avoid leaving it charging all night. But what is really harmful and can affect the life of your phone’s battery, and what is just a myth? Experts and manufacturers detail for EL PAÍS the characteristics of smartphone batteries and debunk many of the legends that persist among users.
Is it harmful to leave your phone charging overnight?
One of the main and most widespread concerns relates to charging your phone overnight. Is it harmful to leave it on the charger all this time? Should it be disconnected once it reaches full charge? The quickest answer with a modern smartphone is clear: there is no problem in leaving your phone on the charger overnight, and there is an explanation to justify it. Manufacturers incorporate systems into devices to protect the battery from potential overcharging. Samsung is clear on this: it’s okay to leave your phone charging all night, as when the battery reaches 100% capacity, “the device charger will not transmit energy to avoid damaging the phone,” they explain.
Apple, on the other hand, addresses this issue by using artificial intelligence in a feature it has dubbed “optimized charging.” Basically, it involves learning the user’s habits (if they wake up daily at 7 a.m., for example), to stop charging when it reaches 80% and allow it to reach full charge when the waking hour approaches. Specifically, Apple specifies that “the iPhone uses machine learning” to understand the daily charging routine, so that “optimized battery charging is activated only when it is expected that the iPhone will be connected to a charger for an extended period.”
In summary: there is no problem with leaving your phone connected to the charger all night.
Is Overusing Fast and Wireless Charging a Problem?
The two major advancements in mobile charging, fast charging, and wireless charging, have revolutionized the way we power our devices. Fast charging reduces charging time by increasing the power input to the device, while wireless charging allows for contactless charging, simplifying the process by merely placing the device on a base. However, both charging systems generate higher temperatures in the device than conventional charging. Does this pose a problem?
According to José Hernández from the repair company Europa3G: “We have firsthand evidence that customers who charge their iPhone with slow chargers (1A) maintain the battery life longer and avoid swelling and damage to the battery. On the other hand, those who use a fast charger (5A) experience faster deterioration in battery life; in some cases, this can cause batteries to swell even before the two-year warranty period. However, these chargers allow the device to be fully charged in an average of 30 minutes to 1 hour in most cases.”
Regarding wireless charging, according to this expert, it does not excessively affect the battery’s health if the charger is approved by the manufacturer: “Wireless charging does not harm at all, as it is a slow-speed charge,” he explains. “What we always have to check is the quality of the wireless charger and make sure that the mobile does not overheat; low-quality chargers can produce excess heat in the mobile,” he adds.
In this regard, Apple warns that “the iPhone may overheat while charging, and to increase battery life, if it gets too hot, the software may limit charging to 80%.” In any case, this type of charging is less efficient because it has lower energy utilization due to losses in power delivery. Samsung, on the other hand, does not make any warnings on the page dedicated to wireless charging, so it is assumed that this is safe and does not degrade the battery.
How to Make Charging Faster While Being Safe?
We have analyzed the advantages and potential drawbacks of fast charging, but… Is there a way to charge faster using a conventional charger? The truth is yes: by putting the device in “airplane mode” while charging. The principle could not be simpler, as it deactivates functions that consume more resources, so that the net energy input is much higher than the output, thus reducing charging times. Is this way of charging much faster?
“Indeed, charging is 10%-15% faster than if it is in normal mode,” explains Hernández, “and this happens because when activating airplane mode, our smartphone disconnects all wireless signals and all external connections like Wi-Fi and Bluetooth, and consequently, consumes minimal energy, so we could say that it is almost 90% at rest.”
Can I Use Any Type of Cable for Charging?
“An unofficial charger does not necessarily damage our phone,” explains Europa 3G, “but there are several critical aspects to consider. It is crucial to choose a charger from a recognized manufacturer, as these undergo rigorous quality controls and usually incorporate safety measures to prevent overcharging or overheating.”
In this regard, the importance of the correct voltage and amperage is highlighted: “Using a charger with specifications different from those recommended by the mobile phone manufacturer can be harmful. If a tablet charger that operates at 45 watts and 6 amps is used on a mobile designed for 5w – 10w and 1A to 3A, this can decrease battery life by 20-30%,” says Hernández.
The selection of the USB cable also plays a vital role, according to the company: “Using a low-quality cable can cause the current to not reach adequately and even cause personal injury if it breaks due to poor manufacturing.” Samsung emphasizes the importance of using “reputable” providers when opting for external cables and chargers; Apple, on the other hand, created the MFI (Made for iPhone) program years ago, through which it approves suppliers that meet its requirements.