Voltage Dropper and Current Switcher for Li-Ion Overcharge Prevention
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Solution Overview
Problem
Lithium ion batteries can be overcharged when charged with a charger designed for lead-acid batteries, leading to an overcharge state due to the difference in charge voltage settings, and existing solutions fail to effectively manage this issue without causing overcharge or overdischarge problems.
Innovation Solution
An energy storage apparatus with a voltage dropper and current switcher configuration that detects voltage exceeding a predetermined value, switching the charge current path through the voltage dropper to prevent overcharge, allowing charging with higher voltages without causing issues, and includes a controller to manage equalization processing for balancing charge among multiple batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a lithium ion battery is charged with a charger designed for lead-acid batteries, then the battery can be charged using existing chargers, but the battery voltage exceeds the allowable charge range causing overcharge
Solution Approach 1:
A voltage dropper is introduced as an intermediary component between the charger and the lithium ion battery. The voltage dropper reduces the charger's output voltage to match the battery's required charge voltage, enabling safe charging with universal chargers while preventing overcharge conditions
2Reliability
If the charge voltage is reduced to match lithium ion battery requirements, then overcharge is prevented, but charging time increases
Solution Approach 1:
The system dynamically switches between two charge paths: a high-voltage path for rapid charging when the battery voltage is below the threshold, and a voltage-dropping path when the battery voltage approaches the threshold. This dynamic adjustment optimizes both charging speed and safety
3Reliability
If a voltage dropper is added to prevent overcharge, then battery safety is improved, but device complexity increases
Solution Approach 1:
The voltage dropper is integrated with the charger circuitry, and the control logic is merged into a single controller that manages both the voltage dropping and the charge path switching. This consolidation reduces overall system complexity despite adding the voltage dropper function
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
Prevents overcharge by lowering the charge voltage when the battery voltage exceeds a predetermined value, ensuring safe charging and maintaining battery health by securing time for equalization processing, even when charged with higher voltages than the battery's full charge voltage, thus preventing unexpected shutdowns.
Implementation Method 1
a voltage dropper configured to drop a charge voltage for the energy storage device
Data Source
AI summary
An energy storage apparatus includes: an energy storage device; a voltage dropper configured to drop a charge voltage for the energy storage device; a current switcher connected in parallel with the voltage dropper; a voltage detection unit configured to detect a voltage of the energy storage device; and a controller. When the voltage of the energy storage device exceeds a predetermined value, the controller causes the current switcher to switch a path of a charge current to the energy storage device to a path through the voltage dropper.