Development of State-of Charge Technology for Zn/Air Battery Systems

The objective of this program is to develop and demonstrate a state-of-charge (SOC) technology for Zinc-Air batteries that accounts for environmental factors (temperature, humidity) and storage factors (O2 exposure times) beyond the discharge profile. The SOC technology should be small and have a low cost impact on the overall Zinc-Air battery. Power consumption for the SOC technology should be minimal over the life of the Zinc-Air battery. In Phase I, a general SOC architecture and its deployment to characterize Zinc-Air battery SOC with respect to discharge rate and environmental factors was developed. The major components of the architecture were (1) Coulomb counter, (2) microcontroller with RAM/ROM, (3) sensors to detect (one or more) of environmental factors, (4) analog preprocessing module and (5) a LED fuel gauge to visually indicate of SOC. The following key factors were determined to influence the accuracy of a SOC system for Zinc-Air when not taken into account: (1) temperature and humidity; and (2) O2 exposure times, shelf life and storage time. A Fuzzy Neural Network (FNN) enabled SOC algorithm was developed based on existing Zinc-Air constant discharge current performance data augmented by additional test data. The feasibility for developing and deploying a SOC indicator system for Zinc-Air batteries has been established. The primary goal of the proposed Phase II program is to develop and integrate prototype SOC indication technology for BA-8180/U (3rd generation) Zinc-Air batteries that accurately accounts for environmental and storage factors. This includes the development and conducting of a test plan that will train the SOC indicator and evaluate its accuracy with BA-8180/U & BA-8140/U (4th generation) Zinc-Air batteries at various states of charge and under various environmental and storage conditions. Finalize the selection of appropriate sensors (w.r.t. cost, size, power consumption), build and demonstrate one lot of prototype devices suitable for advanced laboratory and supervised field-testing. Aggressive commercialization and technology transition plans (Phase III) will be pursued teaming with our industrial partners.