This question for a long time worried our readers, but what to hide, and ourselves, too. In the comments and in various forums, there were different arguments against and in favor of charging the iPhone with a charger from the iPad. We decided to put an end to these disputes and turned to the specialists from the ChargerCube team who created the most reliable and safe charging accessory for Apple devices.
The lithium polymer battery works at potential difference on terminals in the range 2 , 8-4,2 V. Voltage on the contacts of the USB connector in charging is 5 V. For this type of battery, the maximum continuous charge current is the indicator 1CA, where C is the battery capacity in Ampere * hour (for example – here ). The iPhone 5 has a battery capacity of 1440 mAh, that is, an allowable charging current of 1.44 A; in models 6 and 7, the battery capacity is higher and the allowable charging current, respectively, is greater.
To ensure that the voltage on the terminals does not exceed the nominal values, the battery charge controller monitors the battery current, it also monitors the charge current. Such type of controllers are the standard components of any smartphone and do not allow to exceed the maximum allowable charging current. When observing the conditions specified in the specification, the battery manufacturer guarantees the number of charge-discharge cycles, also specified in the specification.
The rated current of the power adapter implies that the adapter can operate without significant consequences for itself (without overheating) in this mode during its service life. Even the iPad, when charging, consumes from the adapter a current of 2.4 A only for the first 5 minutes with a fully discharged battery (before starting the OS), the rest of the charging time, the current is lower, and this current is controlled by the battery controller.
Thus, any smartphone will consume current charging limited by the maximum permissible charging current, that is, a more powerful charger at its nominal value will not have a noticeable effect on the battery capacity.