Online Autonomous Specific Gravity Measurement Strategy for Lead-Acid Batteries

This paper proposes an online autonomous specific gravity measurement strategy for lead-acid battery applications. The main objective of this strategy is to achieve the intelligent and high-precision measurements. In general, the electricity of a lead-acid battery is related to the state-of-charge (SOC), which can be obtained by gauging the specific gravity. However, the traditional process of capturing the lead-acid battery data is relatively complex and time consuming. Moreover, it is difficult to directly transfer the specific gravity data as electronic signals for the battery management system (BMS) by using traditional methods. In view of this, an autonomous strategy with online measurement feature is proposed to gauge the specific gravity. In addition, the liquid level sensing concept combined with the ultrasonic sensor module is adopted. To realize the proposed strategy, a hydrometer integrated with the liquid level sensor is designed and implemented. By utilizing the proposed strategy and developed mathematical equations, the traditional visual inspection data could be transferred as electronic data and combined with the BMS. In other words, the intelligent online real-time monitoring measurement can be achieved whereas the human resources cost can be reduced. Moreover, environmental factors are also taken into account in the proposed strategy to precisely capture the specific gravity under different operating conditions. Finally, experimental results demonstrate the performance and feasibility of the proposed strategy.