EV Battery Capacity Display Using Stored Temperature Data
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Solution Overview
Problem
Electric motor vehicles experience a temporary decrease in residual battery capacity and travelable distance at low temperatures, causing user concern due to inaccurate display of reduced capacity, which is later restored as temperature increases.
Innovation Solution
An information supply device and method that measures and stores secondary cell temperatures before and after vehicle use, calculates residual capacity change using a temperature change relation or map, and determines whether to display a notification based on this change and a human forgetting ratio curve, ensuring users are informed of capacity decreases only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If residual battery capacity is displayed based on low-temperature measurements, then measurement accuracy is improved, but user anxiety increases due to temporary capacity decrease display
Solution Approach 1:
The system performs preliminary action by storing the residual battery capacity value measured before the vehicle stops (when temperature is higher) in advance. This stored value is then used for display after the vehicle restarts, preventing the display of temporarily reduced capacity values that would cause user anxiety. The preliminary measurement and storage of capacity data resolves the contradiction by providing a more representative capacity value that reflects the battery's true state rather than its temporary low-temperature state.
2Measurement precision
If temperature compensation is applied to residual battery capacity calculation, then measurement accuracy at low temperatures is improved, but device complexity increases
Solution Approach 1:
Instead of applying complex temperature compensation calculations, the system uses a simpler copying approach by storing and reusing the residual battery capacity value measured under more favorable temperature conditions (before vehicle stop). This copied value from a previous measurement state avoids the need for complex real-time temperature compensation algorithms while still providing accurate capacity information to the user.
3Reliability
If continuous temperature monitoring and capacity recalculation are performed, then reliability of capacity information is improved, but energy consumption increases
Solution Approach 1:
The system implements periodic action by performing residual battery capacity measurement and storage only at specific intervals - specifically when the vehicle stops and restarts. Rather than continuously monitoring and recalculating capacity, the system captures capacity data periodically at these key moments. This periodic measurement approach maintains reliable capacity information while significantly reducing energy consumption compared to continuous monitoring.
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
The solution accurately assesses and communicates residual battery capacity changes to users, reducing anxiety about temporary capacity drops and enhancing user experience by providing relevant notifications only when significant changes occur.
Implementation Method 1
a temperature measurement unit configured to measure a temperature of the secondary cell
Implementation Method 2
a residual capacity change derivation unit configured to derive a residual capacity change of the secondary cell between the first timing and a second timing at which the driving of the vehicle restarts based on a second temperature of the secondary cell measured by the temperature measurement unit at the second timing and the first temperature read from the storage unit
Implementation Method 3
a display control unit configured to determine whether to cause the display unit to display a predetermined display based on the residual capacity change of the secondary cell derived by the residual capacity change derivation unit and a difference between the first timing and the second timing
Data Source
AI summary
A display device includes: a storage management unit storing a first temperature of a secondary cell measured at a first timing before driving stop of a vehicle in a storage unit in association with the first timing; a residual capacity change derivation unit deriving a residual capacity change of the secondary cell between the first timing and a second timing at which driving of the vehicle restarts based on a second temperature of the secondary cell measured at the second timing and the first temperature read from the storage unit; and a display control unit determining whether the display unit is caused to display a predetermined display based on the derived residual capacity change of the secondary cell and a temporary difference between the first timing and the second timing.