App note from Richtek on how to work with Li-ion batteries properly. Link here
Lithium-ion/polymer rechargeable batteries, which have been widely used today, have distinguished properties, but are very delicate and have to be used with extreme care. Improper use of Li-ion batteries will bring about catastrophic consequences. The incidences of burning and explosions of Li-ion batteries have often been heard. Carefully understanding their properties and adopting a right battery management method is most essential for making good use of Li-ion batteries.
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.
More Li-ion battery applications from Richtek. Link here (PDF)
Lithium-Ion batteries have several advantages when compared with other battery types: They are light weight, and energy density of lithium-ion is typically twice that of the standard nickel-cadmium. Li-Ion batteries have no memory effect, and the self-discharge is 6 ~ 8 times less compared to nickel-cadmium. The high cell voltage of 3.6 volts is often sufficient to power applications from a single cell. These properties make Li-Ion batteries very popular in modern portable electronic applications.
C8051F300 implementation of Li-Ion battery charger from Silicon Labs. Link here (PDF)
Driven by the need for untethered mobility and ease of use, many systems rely on rechargeable batteries as their primary power source. The battery charger is typically implemented using a fixedfunction IC to control the charging current/voltage profile.
The C8051F300 family provides a flexible alternative to fixed-function linear battery chargers. This note discusses how to use the C8051F300 device in Li-Ion battery charger applications. The Li-Ion charging algorithms can be easily adapted to other battery chemistries.