EV Low-Voltage Battery Decoupling During Charging
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Solution Overview
Problem
Electric vehicles with lead batteries face premature failure due to prolonged charging, leading to water loss, corrosion, and internal short circuits, as they are continuously charged while parked, causing hydrogen gas production and overheating.
Innovation Solution
An electric charging method and device that control the DC converter output voltage to prevent current flow to or from the low-voltage battery when its state of charge exceeds a threshold, effectively decoupling the lead battery from the charging process to prevent overcharging and discharging, using an electronic control device to manage the charging process and ensure the battery remains above a critical state of charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead battery is continuously charged while the vehicle is stopped, then the low-voltage energy supply is ensured for electronic control devices, but the battery suffers from water loss, corrosion, and internal short circuits leading to premature failure
Solution Approach 1:
The patent implements periodic charging action by controlling the DC converter to charge the lead battery only during specific time periods when the vehicle is not connected to external power sources. The control device monitors the charging state and automatically stops charging when the battery reaches a predetermined charge level, preventing continuous charging damage while ensuring the battery remains functional for low-voltage consumers.
2Ease of operation
If the DC converter continuously charges the lead battery, then the low-voltage consumers are powered, but hydrogen gas production and heat generation increase causing safety risks
Solution Approach 1:
The patent employs feedback control through a control device that continuously monitors the charging state of the lead battery, the output voltage of the DC converter, and the state of charge of the traction battery. Based on this feedback information, the control device automatically adjusts the charging process, stopping charging when the lead battery reaches a predetermined charge level or when the vehicle is connected to external power, thereby preventing hydrogen gas production and overheating while maintaining automatic operation.
3Productivity
If the lead battery is used to power low-voltage consumers during traction battery charging, then the charging efficiency is improved, but the lead battery may be discharged below the critical state of charge level
Solution Approach 1:
The patent implements dynamic control of the DC converter output voltage to balance the charging efficiency and battery state of charge. The control device dynamically adjusts the converter's output based on real-time monitoring of the lead battery's charge level and the traction battery's charging status, ensuring that the lead battery is charged during external power connection while preventing discharge below critical levels during unattended charging operations.
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 method protects the lead battery from damage during prolonged charging, maintains its state of charge above a level necessary for proper electrical function, and prevents premature failure, thereby extending the battery's lifespan.
Implementation Method 1
converting an electric voltage provided by the external energy source into a low DC voltage
Data Source
AI summary
A system and method for charging a vehicle having a first battery, such as a high-voltage traction battery, and a second battery, such as a low-voltage battery, include controlling a DC converter or relay to effectively decouple the second battery from the converter when the vehicle is connected to an external power source to reduce or prevent damage to the second battery from extended or prolonged charging. The second battery may be effectively decoupled from the converter by controlling the relay or converter voltage based on state of charge of the second battery so that substantially zero current flows to and from the second battery relative to the converter and any vehicle low voltage consumers/accessories.