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Ever wondered how our phone knows the state of charge of the battery inside it. What could be woking in the background that make us know the state of battery charge in our phone? In this article we will try to understand how the phone know the state of charge of the battery.
Firstly, we have the battery fuel gauge ICs. Battery fuel gauge ICs is usually located in the battery pack or in the device itself and perform integrated functions of monitoring the battery voltage, current and temperature. With the help of a built-in Coulomb counter, these fuel gauge ICs calculate battery charge and store the data in 16-bit resolution for retrieval by the system controller. Access is through an industry-standard I²C interface, enabling the controller to create an accurate graphical representation of the remaining battery-operating time.
Battery-monitoring fuel gauge ICs combine a small footprint with outstanding measurement accuracy and extremely low power consumption to increase battery runtime and lifespan in mobile phones, multimedia players, digital cameras, and other space-constrained portable gadgets.
Secondly, is the Coulomb Counting technique. Coulomb counting is a technique which track the State of Charge of a battery pack. It works by integrating the active flowing current (measured in amps) over time to derive the total sum of energy entering or leaving the battery pack. This produces a capacity that is typically measured in Amp-hours.
Thirdly, is the Impedance tracking. The Impedance Tracking technology precisely gauges changes in impedance, or resistance caused by battery age, temperature and cycle patterns, to accurately make a prediction of the run time of two-cell, three-cell and four-cell battery packs. It analyzes the precise state of charge when a battery pack is in a relaxed state by correlating between a battery pack´s open circuit voltage and the current state of charge and temperature.
So hopefully this has cleared the mystery behind as to how the smartphone knows the charge of the battery.
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