To keep pace with increasing power requirements of portable electronic devices, not only are new power technologies being sought, but existing technologies, such as lithium ion rechargeable batteries, are being maximized through use of new tools such as "fuel gauging."

Fuel gauging (also called "gas gauging") is a "smart battery" process that maximizes battery use by closely monitoring a battery or battery packs capacity throughout its entire life so that its charge level, also called State of Charge, and thus, remaining life, can be estimated and increased.

Battery monitoring is enabled through a fuel-gauge standard communications protocol—most likely, System Management Bus (SMBus)—which can additionally provide an LED or LCD readout display.

Battery monitoring through the SMBus is directed by a fuel-gauge integrated circuit (IC), many of which have patented algorithms used to learn battery characteristics, as is the case with Texas Instruments' (TI) Impedance TrackTM technology.

Currently used in Ultralife Batteries brand lithium ion batteries ranging from medical to military use, TI's Impedance Track technology implements a dynamic modeling approach which continually tracks and learns the battery's characteristics, making adjustments as needed.

To track and learn the battery's characteristics, the TI fuel gauge IC takes into consideration the chemical identity of the lithium ion cells used, from which it then creates voltage and impedance threshold values to check against.

The fuel gauge IC also uses a cell balancing system that monitors and corrects cell-to-cell voltage variations within the battery pack, which is critical to not just increasing system run time but to the life of the battery pack itself.

Thus with the aid of the knowledge of real-time, cell-specific impedance measurements, Ultralife batteries continuously undergo checks and compensation for load and temperature, thereby bypassing thermal shutdown or any other premature end-of-life fate which wastes battery capacity.