Dynamic Battery Charging Threshold for Fuel Economy
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Solution Overview
Problem
Automotive battery-charging systems face challenges in balancing battery life and fuel efficiency, as existing strategies either deplete the battery when parked or reduce fuel economy by maintaining high state of charge, and there is a need for a dynamic charging threshold based on battery capacity and key-off load to optimize charging.
Innovation Solution
A controller-programmed battery-charging system that adjusts output power based on throttle body opening, engine efficiency, and state of charge, using a dynamically calculated minimum SOC threshold to switch between smart-charging and default-charging strategies, ensuring adequate battery charge without reducing fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery-charging system maintains high state of charge to ensure adequate battery charge for engine start, then battery reliability is improved, but fuel economy deteriorates due to increased alternator power output
Solution Approach 1:
The charging system dynamically adjusts the state of charge threshold based on measured battery capacity and key-off load conditions. The threshold is not fixed but varies according to actual battery health and vehicle electrical demands, allowing the system to optimize between battery reliability and fuel economy in real-time
Solution Approach 2:
The system changes the charging parameter (state of charge threshold) based on measured conditions. When battery capacity is high and key-off load is low, the threshold is reduced, allowing lower state of charge operation that improves fuel economy while still maintaining adequate battery charge for reliable engine starting
2Use of energy by moving object
If the battery-charging system depletes the battery to reduce fuel consumption, then fuel economy is improved, but battery life deteriorates due to excessive discharge
Solution Approach 1:
The system continuously measures battery capacity and key-off load, then uses this feedback to adjust the state of charge threshold. This closed-loop control ensures the battery is not depleted below safe levels while still allowing sufficient discharge to improve fuel economy when conditions permit
Solution Approach 2:
The charging strategy dynamically adapts to battery condition and vehicle demands, adjusting the minimum state of charge threshold rather than using a fixed value. This allows the system to maximize fuel economy improvements while protecting battery life based on actual battery health
3Reliability
If the charging system uses a fixed high state of charge threshold, then battery reliability is maintained, but fuel economy deteriorates due to unnecessary charging
Solution Approach 1:
The system changes the state of charge threshold parameter from a fixed high value to a dynamic value based on measured battery capacity and key-off load. When battery health is good and electrical demands are low, the threshold is reduced, eliminating unnecessary charging that would waste fuel while still maintaining adequate battery charge
4Use of energy by moving object
If the charging system dynamically adjusts state of charge threshold based on battery capacity and key-off load, then fuel economy is improved, but device complexity increases due to additional sensing and control logic
Solution Approach 1:
The battery management system uses its existing measurement capabilities (battery capacity and key-off load sensing) to self-adjust the charging threshold without requiring additional complex external systems. The controller already has the necessary information to make intelligent charging decisions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach optimizes battery life and fuel efficiency by charging the battery strategically, maintaining a lower target SOC to reduce fuel consumption while ensuring the battery remains adequately charged for engine start, even after long periods of inactivity.
Implementation Method 1
a battery-charging system electrically connected to the battery and configured to convert mechanical motion of the engine into electricity to charge the battery
Data Source
AI summary
A vehicle includes an engine having a throttle body, a battery, e.g., a 12-volt battery, and a battery-charging system electrically connected to the battery and configured to convert mechanical motion of the engine into electricity to charge the battery. A controller of the vehicle is programmed to, in response to an opening of the throttle body being less than an opening threshold and a state of charge of the battery (battery SOC) being less than a first charge threshold, set the battery-charging system to output a first power, wherein the charge threshold is based on a measured capacity of the battery and a measured key-off load. The controller is further programmed to, in response to the opening being less than the opening threshold and the battery SOC exceeding the first charge threshold but being less than a second charge threshold, set the battery-charging system to output a second power that is less than the first power.