Battery and System Health Monitoring of Battery Powered Smart Flow Meters Reference Design
Created: Jul 25, 2018
Smart water, gas, and heat meters continue to evolve and add new features and capabilities but must still have an operational life of at least 10 years. This standard increases pressure on battery performance. Whether due to hardware or software issues, any malfunction of the system can impact battery life and therefore product life. The battery and system monitoring solutions in this reference design help protect against such issues and provide service operators greater insight into projected product life expectancy. This insight helps the operators optimize meter replacement and service costs. The battery monitoring circuitry accurately monitors the battery state of non-rechargeable LiSOCl2 and LiMnO2 batteries used in smart flow meters. The functionality of primary battery monitoring is achieved by using a bq35100 battery fuel gauge monitor, which provides the State-Of-Health (SOH) and End-OfService (EOS) data. The data provided by the bq35100 can be correlated with the flow meter power consumption to accurately schedule the service replacement. The circuitry for system health monitoring monitors the health of flow meters. Any malfunctioning of the flow meter due to software or hardware issues can lead to excess current consumption and negatively impact the battery life. The system health monitoring functionality is achieved by using a ADS7142 nanopower system monitor and LPV521 op amp. The ADS7142 provides programmable threshold settings to autonomously monitor the changes in battery current and to ensure the flow meter is functioning within the operating limits.
This reference design showcases innovative solutions for battery and system health monitoring of battery-powered Smart Flow Meters. The battery monitoring subsystem provides highly accurate energy measurement and State of Health (SOH) projections which forecast battery lifetime. The system monitoring subsystem protects against over current conditions which can dramatically reduce battery life. The techniques demonstrated here can help extend the effective life of battery-powered meters and optimize total cost of ownership for utility operators.