Battery Life Estimation Using Partial Discharge Monitoring
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Solution Overview
Problem
Existing methods for determining battery capacity in battery-based uninterruptible power supplies (UPSs) are inefficient, often requiring full discharge, which can lead to late or premature battery replacement due to reliance on age alone, ignoring other factors like temperature and usage patterns.
Innovation Solution
A method and apparatus for estimating battery lifetime by monitoring charge and discharge characteristics, operating conditions, and environmental factors, calculating battery life values based on these factors, and adjusting for temperature and discharge rates to provide a more accurate remaining lifetime estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full discharge testing is performed to determine battery capacity, then measurement precision is improved, but loss of time increases and reliability deteriorates
Solution Approach 1:
The system performs preliminary monitoring of battery charge characteristics during normal operation (float charging, discharge events) before a full discharge test is needed. By accumulating data during these preliminary periods, the system can estimate battery life without waiting for a complete discharge cycle, thereby reducing the time loss associated with testing.
Solution Approach 2:
Instead of requiring a complete full discharge test (excessive action), the system uses partial discharge data and float charging characteristics to estimate battery capacity. This partial action approach provides sufficient measurement precision for replacement decisions without the time cost of complete depletion.
2Ease of operation
If battery replacement is based solely on age, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The system continuously monitors battery charge characteristics (voltage, current, temperature) during float charging and discharge events, using this feedback to dynamically adjust the remaining life estimate. This feedback mechanism maintains ease of operation by providing automatic estimates while improving precision by incorporating actual performance data beyond simple age tracking.
Solution Approach 2:
The battery management system performs self-assessment by monitoring its own charge characteristics and calculating remaining life without external intervention. This self-service approach improves measurement precision by using detailed electrical and thermal data while maintaining ease of operation through automated decision support.
3Measurement precision
If periodic discharge testing is performed to verify battery capacity, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The system uses periodic float charging and discharge events that occur during normal UPS operation to gather battery performance data. By leveraging these naturally occurring periodic actions, the system achieves capacity verification without requiring separate dedicated testing periods, thus maintaining UPS productivity.
Solution Approach 2:
The monitoring system operates continuously during normal battery charging and discharging, accumulating data without interrupting UPS service. This continuous data collection during useful operations maintains measurement precision while avoiding productivity loss from scheduled outages.
Data Source
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AI summary
A method of estimating battery lifetime includes monitoring a charge characteristic of a battery during a first time period, monitoring an operating condition of the battery, determining a first battery life value for the first time period based on the operating condition of the battery, the charge characteristic, and a duration of the first time period, determining an overall battery life value using the first battery life value and a second battery life value for a second time period, and estimating a remaining battery lifetime for the battery based on the overall battery life value.