Battery Pack Temperature-Adaptive Charging Control
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Solution Overview
Problem
Lithium-ion batteries have a low tolerance for overcharging or overdischarging compared to nickel-cadmium or nickel-hydride batteries, which can reduce their lifespan and capacity, necessitating advanced protection mechanisms in battery packs.
Innovation Solution
A battery pack with a control circuit that adjusts charging voltage based on temperature, using a selection circuit to output charge control signals from different detectors depending on battery temperature, allowing for multi-step constant-current charging and constant-voltage charging to prevent overcharging while optimizing capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium-ion battery is charged to high voltage to increase capacity, then the battery capacity increases, but the battery lifespan reduces due to overcharging damage
Solution Approach 1:
The patent applies dynamics by making the charging voltage threshold dynamic rather than fixed. The first predetermined value (overcharge threshold) is adjusted based on the second predetermined value (discharge threshold), creating a flexible charging window that adapts to battery state, thereby preventing overcharging while maximizing capacity utilization
Solution Approach 2:
The patent changes the voltage parameters dynamically. By adjusting the first predetermined value based on the second predetermined value, the system modifies the charging voltage threshold parameter in real-time, allowing optimal charging that extends lifespan while maintaining capacity
2Device complexity
If a fixed charging voltage threshold is used to simplify control, then the control system is simple, but the battery lifespan is reduced due to inability to adapt to battery state
Solution Approach 1:
The patent implements parameter changes by making the charging threshold voltage dynamic. The first predetermined value is adjusted according to the second predetermined value, allowing the control system to adapt to battery state without requiring complex external control mechanisms
Solution Approach 2:
The battery pack performs self-service by using its own discharge threshold information to determine its charging threshold. This self-determined parameter adjustment eliminates the need for complex external control systems while extending battery lifespan
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 effectively prolongs the lifespan of lithium-ion batteries by adjusting the charging voltage according to temperature, preventing overcharging and maintaining capacity, thus addressing the limitations of lithium-ion batteries.
Implementation Method 1
a temperature measuring element (thermistor) Th for detecting a temperature of the battery assembly 4
Implementation Method 2
an electric current flowing in a heater resistor 6a melts a fuse element 6b to open a flow path of the electric current
Data Source
Figure 1
Figure 2(a)~2(g)
Figure 3(a)~3(g)
AI summary
A battery pack (1) which is detachably connected to a charger (2) and charged by connecting thereto, includes a battery assembly (4) including a plurality of secondary batteries (4A-4D) serially connected; a pair of power terminals (5c,5b) connected to a negative and a positive electrode of the battery assembly, respectively; a control circuit (7) adapted to individually detect voltages across respective secondary batteries (4A-4D) and output a charge control signal to the charger (2) when the detected voltages exceed a predetermined value; a signal terminal adapted to output the charge control signal to the charger (2); and a temperature measurement element (Th) for detecting a temperature of the battery assembly (4). Further, the control circuit (7) changes the predetermined value to be compared with the detected voltages based on the detected temperature of the temperature measurement element (Th).