App note: How to achieve greater accuracy in battery capacity readings for portable designs


App note from Maxim Integrated on using fuel gauge IC to obtain accurate battery state of charge readings. Link here (PDF)

Because a product’s runtime is limited by battery capacity, it’s critical to have a precise method for measuring the remaining battery capacity to avoid an unexpected shutdown. This application note describes an experiment for obtaining accurate battery capacity readings in a dog-tracking project.

App note: Li-ion battery and gauge introduction


Richtek app note for Li-ion battery definitions and gauge introduction. Link here

SOC is defined as the status of available energy in the battery and usually expressed as percentages. Because the available energy change depends on different charging/discharging currents, temperatures and aging effects, the SOC could be defined more clearly as ASOC (Absolute State-Of-Charge) and RSOC (Relative State-Of-Charge). Typically, the range of RSOC is from 0% to 100%, a fully charged battery’s RSOC is always 100% and a fully discharged battery has 0% RSOC. The ASOC is a reference calculated by Design Capacity which is a fixed capacity from when the battery is manufactured. A fully charged new battery will have 100% ASOC, but a fully charged aging battery could be less than 100% because of different charge/discharge conditions.

Battery management is part of power measurement. The fuel gauge is responsible to estimate the capacity of battery in the domain of battery management. The basic function of fuel gauge is to monitor the voltage, charge/discharge current and battery temperature, and to estimate the battery’s SOC and Full Charge Capacity (FCC) of battery. There are two classic methods to do the SOC estimation which are Open Circuit Voltage (OCV) and Coulomb Counter, respectively. The other method is dynamic voltage-based algorithm designed by RICHTEK.

App note: Battery fuel gauge IC (LC709203F) for 1-Cell Lithium-ion (Li+)


Lithium-ion fuel gauge IC from ON Semiconductors. Link here (PDF)

The LC709203F is an IC that measures the remaining power level of 1-cell lithium-ion (Li+) batteries used for portable
equipment etc.
This product reduces fuel gauge errors with a unique correction technology during measurement of battery temperature and
This technology has inherently high precision without the need for an external sense.