Automatic battery charging system on android smartphones

A smartphone needs a battery source to work well. During the battery charging process, the state of charge can be increased by up to 100%. One habit of charging batteries is to leave the smartphone connected to the charger all night long. Batteries that are already 100% but still connected to the charger will continue to receive an electric current even though a small value can cause a decrease in battery life and durability. This final project aims to create an automatic battery charging system based on the Android operating system. The result of this system is when the percentage limit that we have set is the same as the percentage of the battery on the smartphone, the system will automatically cut off the incoming current so that the charging process will stop. This system is designed using a microcontroller, Bluetooth module, relay module, Android apps, and smartphone with an Android operating system. The tests are the suitability of the apps with the smartphone, the charging and discharging conditions on the system, and automatic battery charging. From the results of the tests, the system can cut the current to a value of 0 amperes from the charger manually and automatically controlled through the apps, the apps can be used on smartphones that have Android version 2.1 or higher.