Battery Pack Auxiliary Activation Circuit for Overcharge Protection
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Solution Overview
Problem
Lithium-ion battery packs face safety issues due to overcharge or overdischarge risks, especially when the activation signal from external devices is absent, leading to potential battery damage or overcharging.
Innovation Solution
A battery pack design incorporating a protective circuit with an auxiliary activation circuit that generates an internal activation signal when the battery receives power from a charger, ensuring the protective circuit is activated even without an external activation signal, using a series circuit of a zener diode and resistor to determine if power is being received, and a fusing resistor to interrupt charging when overcharge is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the protective circuit is switched to rest state or standby state when the battery pack is not connected to the charger or when the load device is turned off, then the current consumption of the protective circuit is reduced, but the protective circuit cannot perform protective operation when charging is needed
Solution Approach 1:
The battery pack performs self-detection of charging state through the charging detection circuit connected to the charging terminal, and automatically activates the protective circuit based on detected charging voltage, enabling the system to serve itself without external activation signals
Solution Approach 2:
The charging detection circuit continuously monitors the charging terminal voltage and provides feedback to the control circuit, which then controls the protective circuit's operation state based on the detected charging condition, creating a closed-loop control system
2Device complexity
If the activation signal is sent only from the charger, then the system structure is simple, but the charging process cannot be safely controlled when the charger breaks or contact failure occurs
Solution Approach 1:
The battery pack independently detects charging state through its own charging detection circuit and activates protective functions without relying on external activation signals from the charger, making the system self-sufficient for safety control
Solution Approach 2:
The protective circuit is pre-configured to be automatically activated when charging is detected, providing beforehand protection against potential charger failures or contact issues before they can cause damage
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 battery overcharge and overdischarge by ensuring the protective circuit is always active during charging, enhancing safety and reliability by maintaining the battery in a controlled state, even without external activation signals, thus preventing battery deterioration and ensuring safe charging.
Implementation Method 1
The auxiliary activation circuit is configured to generate an internal activation signal in response to detection that a voltage of the charging terminal is not less than a predetermined threshold value
Implementation Method 2
a fusing resistor to interrupt charging when overcharge is detected
Data Source
Figure 1
Figure 2
AI summary
The battery pack includes: a charging terminal receiving power from a charger while connected to the charger; a battery connected to the charging terminal and recharged by power from the charger via the charging terminal; a protective circuit performing a protective operation of detecting an overcharge of the battery by using power from the battery while receiving a driving signal, and terminating the protective operation when receiving no driving signal; an activation terminal receiving an activation signal from the charger while connected to the charger; an activation circuit connected to the activation terminal and configured to output the driving signal to the protective circuit while receiving the activation signal from the charger via the activation terminal; and an auxiliary activation circuit connected to the charging terminal and configured to provide the driving signal to the protective circuit while the battery receives power from the charger via the charging terminal.