In general, Lithium-ion (Li-ion) batteries are a preferred energy storage and power delivery system for a wide range of applications, including uninterrupted power supplies (UPS), electric vehicles (EV), airplanes, ships, computers, and smart phones. All such equipment and technologies demand efficient stored energy use, high power, fast recharge, and battery safety (e.g., avoiding cell venting, explosion, thermal runaway, and battery fire).
Conventional battery systems provide crude battery monitoring techniques to support efficient stored energy use, high power, fast recharge, and battery safety. Yet, conventional battery systems are limited in their support, while failing to provide diagnosis, forensic, and management capabilities that properly measure and maintain Li-ion batteries.
For instance, conventional battery systems can only monitor DC cell voltage, cell current, and surface temperature (Tsurf, using thermocouples or thermistors), exclusively. Further, some conventional battery systems can measure AC impedance, but only at a single frequency, typically the amplitude of the impedance at 1 kHz, which provides information solely on the electrolyte resistance (Rs). Moreover, other conventional battery systems can monitor the battery voltage (Vbat), but not individual cell voltage. Since Tsurf, Rs, and Vbat do not provide useful information about battery safety or efficient utilization of the stored energy, monitoring of such parameters by conventional battery systems cannot fulfill battery safety demands.