Simply charging the smartphone overnight is practical. In the morning the battery is full and you can get through the day without having to plug it in again. However, there are concerns that the long charging time could damage the smartphone battery.
One hears it again and again: It is simply not good to keep the battery connected to the power for hours and thus “overcharge” it. So much for the technology myth. But can that really happen and end up damaging the smartphone? A tech expert explains to TECHNOLOGY BUTTON what exactly can happen if you charge your smartphone overnight.
Overnight charging will reduce the battery life
The battery expert from the Association of Electrical, Electronics and Information Technology, Dr. Kerstin Sann-Ferro gives the all-clear, at least in terms of safety: “If a cell phone user charges his battery overnight with a high-quality charging cable, this is not a problem from a safety point of view.” The situation is different with the life of the battery. “As soon as the battery is fully charged, the charging process is interrupted,” explains Sann-Ferro to TECHNOLOGY BUTTON. Every lithium battery must have a so-called charging circuit. As soon as the device reaches the 100 percent mark, it switches off the power supply. So if the battery is full overnight, it will automatically continue to run with external energy from the socket.
“However, if the state of charge falls below a certain value, it is recharged again. This recharging in high charge states puts a strain on the materials and thus has a long-term effect on the capacity and thus on the service life of the battery, ”says Sann-Ferro. Charging at night can cause your smartphone battery to suffer and its service life will decrease faster.
But does it make a difference whether the smartphone is switched on or shut down? In fact, this can be relevant if you’re charging your phone overnight. “If the mobile phone is switched off during the charging process, no ‘consumer functions’ are actually active, so that a drop in the charge level does not occur quickly and therefore less or no recharging is necessary during the overnight period,” says Sann-Ferro.
Many smartphones have a protective mechanism for charging at night
The manufacturers are aware that constant charging to 100 percent overnight has a lasting effect on the smartphone battery. Apple was the first manufacturer to integrate charging protection in iOS. Thanks to optimized charging , the iPhone only fills the battery up to 80 percent capacity at night in order to conserve the battery cells. After a short time, the iPhone learns when to get up in the morning and only charges the battery to 100 percent shortly before that. The option is already switched on at the factory.
From version 11 this function is also available in the Android operating system. Some smartphone manufacturers have also integrated optimized overnight charging into their own Android interfaces beforehand. This function is still missing, especially on older and cheaper devices with outdated Android versions.
Also interesting: That’s why you should never charge your phone in bed
Charge the battery properly
In general, it is advisable to never fully charge or discharge the battery. The smartphone battery is best saved when the charge level is between 30 and 70 percent. Users should only use the charging cable when more than half of the energy has been consumed. “If you have the opportunity to pay attention to this, you should recharge your smartphone at the latest when the charge level is 30 percent, either in small intermediate cycles or in a longer charging cycle and then stop the charging process again when the charge level is 90 percent. This means that the high performance of the battery can be extended over its service life.
Overall, a lithium-ion battery is more temperature-sensitive than previous battery technologies such as NiMH. Temperatures that are too high or too low can cause problems for a lithium-ion battery. Incidentally, it charges ideally at room temperature. Temperatures above 40 degrees and low temperatures below -10 degrees can have a negative impact on charging the battery. “For example, you shouldn’t charge your cell phone below 0 degrees. Most cell phones switch off here anyway and usually do not allow charging at all, ”says the expert. Mobile phone users should never put their smartphones in the blazing sun, especially at high temperatures.
And not only at night: If the battery constantly draws power from the socket, this can put a strain on the battery. Most smartphone owners can rest assured, however. “Really serious charging errors are already caught by the battery management systems,” says Dr. Kerstin Sann-Ferro.
Beware of too much heat
Another rumor is true: you can safely charge your smartphone overnight, but you shouldn’t do it in bed. The heat generated here can damage the device and even the owner, because it can easily lead to a build-up of heat and even a fire. TECHNOLOGY BUTTON explains the myth in detail again in this article .