Characterizing a Lithium-Ion (Li ) Cell for Use with an Open-Circuit-Voltage (OCV) Based Fuel Gauge

The DS2786 stand-alone, open-circuit-voltage (OCV) based fuel gauge estimates the available capacity of rechargeable lithium-ion (Li+) batteries based on the cell voltage in an open-circuit state following a relaxation period. The open-circuit voltage is used to determine relative cell capacity based on a lookup table stored in the IC. The DS2786 leaves the factory with a best-fit OCV profile loaded into the EEPROM of the device. The accuracy of the DS2786 can be improved by customizing the OCV profile of the Li+ cell with the charge and discharge parameters that are used in the application.

This application note outlines a method for characterizing a Li+ cell for use with an OCV-based fuel gauge, collecting and interpreting the data, and then loading the data into the DS2786K evaluation software.