EV Battery Charge Scheduling to Prevent Thermal Shock
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Solution Overview
Problem
Electric vehicle and construction machine batteries face premature degradation due to fast charging and high state of charge storage, which can lead to reduced capacity and lifespan, necessitating a method to manage charging that balances battery health with operational readiness.
Innovation Solution
A method and controller for managing the state of charge and temperature of electric work vehicle batteries, allowing users to select a charge mode based on immobilization duration, calculating a targeted charge increase and temperature change to ensure the battery is at optimal levels at the time of return to work, thereby slowing degradation and preventing thermal shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fast charging is used to ensure operational readiness, then the vehicle is ready for use quickly, but battery ageing increases due to thermal shock and high charge rates
Solution Approach 1:
The system performs preliminary actions by scheduling charging to occur before the vehicle is needed, rather than charging immediately before use. The battery is charged during periods when the vehicle is immobilized, allowing charging to happen in advance without rushing the battery, thus avoiding thermal shock while ensuring readiness when needed.
Solution Approach 2:
The charging system dynamically adjusts the charge rate based on the expected duration of immobilization. For longer immobilization periods, lower charge rates are used to reduce battery degradation, while still ensuring the battery reaches adequate charge levels before the vehicle is needed again.
2Loss of time
If the battery is stored at high state of charge to ensure readiness, then the vehicle can be used immediately, but battery ageing increases due to high state of charge storage
Solution Approach 1:
The system charges the battery in advance during immobilization periods, so the battery does not need to be maintained at high state of charge continuously. By scheduling charging to occur when the vehicle is not in use, the battery can be topped up before needed without requiring constant high state of charge storage.
Solution Approach 2:
The system changes the state of charge parameter dynamically based on the expected duration of immobilization. For longer immobilization periods, the battery is maintained at lower state of charge to reduce ageing, while still ensuring adequate charge levels are reached before the vehicle is needed again.
3Reliability
If low charge rates are used to reduce battery degradation, then battery lifetime is extended, but the time to charge the battery increases
Solution Approach 1:
The system performs charging as a preliminary action during immobilization periods, rather than as a rushed operation before use. This allows lower charge rates to be used without compromising operational readiness, since the charging happens in advance when time is not critical.
Solution Approach 2:
The charge rate is dynamically selected based on the expected duration of immobilization. For longer immobilization periods, lower charge rates are appropriate since there is ample time. The system adapts the charge rate to match the available time window, optimizing both battery health and charging efficiency.
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 prolongs battery lifetime by storing batteries at a low state of charge and using slower charge rates when not needed, while ensuring the battery is ready for use, thus combining long-term health with operational readiness.
Implementation Method 1
Fast charging can increase battery ageing, for example due to thermal shock
Data Source
AI summary
A method for managing state of charge of a battery of an electric work vehicle to be ready to return to work at a return to work time that coincides with an end of a duration of immobilization. A charge mode is selected via a user interface. An initial state of charge of the battery and a target operational state of charge of the battery are used to calculate a targeted charge increase. A charge cycle comprising a charge rate is selected based on the charge mode and the targeted charge increase. A charging start time is calculated such that at the return to work time an actual state of charge of the battery corresponds to the target operational state of charge. The temperature of the battery is adjusted to be a target temperature at the charging start time. The charge cycle is started at the charging start time.