Because most of the current mobile phone batteries cannot be replaced by themselves. Apple recently raised the price of battery replacement again without warning, causing many people to become concerned about battery life. Apple’s official website has long promoted that charging to 80% is not only fast charging but also helps extend battery life. After the new iPhone 15 was launched, iOS17 added an optimal charging option that can set a maximum of 80%.
Why can setting 80% as the charging limit for lithium batteries extend their service life? Here is an analysis:
As smartphone applications become more and more diverse and 5G communications consume more power, mobile phone batteries consume more and more. In addition to increasing battery capacity and charging speed, mobile phone manufacturers also remind users to adopt correct charging habits to extend battery life. To avoid the risks caused by charging, lithium batteries will change to trickle charging when the charge reaches 80%. Most manufacturers will tell you that setting a charging limit of 80% will not only allow for fast charging, but also extend battery life.
The latest iPhone 15 series has a new “Battery Health and Charging” option. Users only need to “Settings”, “Battery”, “Battery Health and Charging”, click “Charging Optimization”, and then select “80% Upper Limit” to set the charge to only 80% to extend battery life: if this function is turned off, the phone will return to 100% charge.
Not only Apple has begun to provide various devices with settings to increase the charging limit of lithium batteries to 80%, but Asus laptops have also long ago recommended that users should set the [Balanced Maintenance Mode] in the battery health charging options, which means setting the charging limit to 80%.
Why do many manufacturers or experts advocate that maintaining the charging capacity of lithium batteries between 30% and 80% will help extend battery life?
Setting the charging limit to 80% is related to the isolation film that protects the lithium battery.
There is electrolyte between the positive and negative electrodes of lithium batteries, which is in a liquid state. During charging and discharging, lithium ions swim between the positive and negative electrodes. However, if the positive and negative electrodes are not isolated and the “lithium ion flow rate” is controlled, the battery will cause a short circuit due to the instantaneous generation of a very large current, and then generate high temperatures according to Joule’s law, so the lithium battery must be separated by an isolation film. If the capacity of a lithium battery is lower than 30% or higher than 80%, the “internal pressure” generated by the battery’s charging and discharging at this time will be greater than usual. Once this internal pressure is too large and not controlled well, it may cause damage to the isolation membrane and cause a short circuit between the different electrolytes between the positive and negative electrodes. In order to prevent the risk of short circuit caused by excessive stress inside the battery, charging will be changed to “trickle” charging when the current power of the lithium battery is higher than 80%. If the upper limit of the charging capacity is limited to 80%, the battery can be charged in a stable fast charging mode and avoid damage to the isolation film caused by high temperatures during charging, which will help extend the service life of the battery.
Therefore, keeping the battery charging limit at 30%~80% can extend the service life of lithium batteries is not just a legend, it is indeed a charging method recommended by the industry.In the past, because the battery charge limit could not be set, it would be troublesome to maintain it at 80% every time. However, many manufacturers have now added a charging optimization mode that can set the 80% charge limit, so you don’t have to worry about it anymore. If it is only for daily use (not for long trips or high power consumption situations), it is recommended to set the battery charging mode to the upper limit of 80%, which will help maintain the health of the battery. Not only can it extend the service life of the mobile phone, but it can also be sold at a good price if it is sold as a second-hand mobile phone in the future!
Source: KOCPC Chinese