Stop/Start Battery SOC Threshold Adjustment for Cycle Life
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Solution Overview
Problem
Lead-acid batteries in vehicles that undergo automatic stop-start cycles face reduced cycle life due to deep discharging, which is difficult to predict and manage without infrastructure-to-vehicle communication, leading to potential battery degradation.
Innovation Solution
Adjusting the minimum battery state of charge threshold for automatic engine stopping based on battery temperature to prevent deep discharging, allowing the battery to maintain a higher charge level during stops and reducing the frequency of deep discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped for a longer period of time with high electrical load, then fuel economy is improved, but the battery undergoes deep discharge cycles reducing cycle life
Solution Approach 1:
The patent applies dynamics by making the minimum battery state of charge threshold adjustable rather than fixed. The controller dynamically modifies the threshold based on battery temperature conditions, allowing the system to adapt between fuel economy optimization and battery protection modes. This resolves the contradiction by enabling the threshold to flex between lower values (for fuel economy) and higher values (for battery protection) based on real-time temperature feedback.
Solution Approach 2:
The patent directly applies parameter changes by modifying the minimum battery state of charge threshold parameter in response to battery temperature. When temperature exceeds a threshold, the minimum state of charge parameter is increased to prevent deep discharge. This parameter adjustment strategy resolves the contradiction between fuel economy and battery cycle life by changing the operational parameter based on thermal conditions.
2Reliability
If the minimum battery state of charge threshold is lowered to extend cycle life, then battery cycle life is improved, but the battery may not maintain sufficient charge during extended stops
Solution Approach 1:
The system dynamically adjusts the minimum battery state of charge threshold based on temperature conditions. During extended stops with high electrical load, the threshold remains lower to preserve cycle life, while the system monitors charge levels to ensure sufficient capacity is maintained. This dynamic approach resolves the contradiction by allowing flexible threshold management rather than a fixed compromise.
Solution Approach 2:
The patent employs feedback by continuously monitoring battery temperature and charge state, then adjusting the minimum threshold accordingly. The controller receives feedback on battery conditions and modifies the threshold parameter to balance cycle life extension with sufficient charge maintenance. This feedback mechanism resolves the contradiction by enabling real-time optimization of the threshold parameter.
3Productivity
If infrastructure to vehicle communication is used to predict stop duration, then engine stop timing can be optimized, but the system complexity and communication requirements increase
Solution Approach 1:
The patent applies self-service by enabling the battery management system to autonomously optimize engine stop timing based on internal temperature and charge state measurements, without requiring external communication infrastructure. The system serves itself by using its own sensor data to adjust the minimum threshold and make stopping decisions, eliminating the need for complex V2I communication systems while maintaining optimization capability.
Data Source
AI summary
Systems and methods for improving operation of a vehicle are presented. In one example, a minimum battery state of charge (SOC) threshold for automatic engine stopping is adjusted responsive to a temperature of a battery. An engine of the vehicle may be automatically started responsive to a battery SOC discharge amount that is greater than a threshold. The approach may allow a battery to discharge a greater number of times so that battery life may be extended.