Battery Charge Voltage Step-Down for High-Charge Swelling Control
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Solution Overview
Problem
Rechargeable batteries, such as lithium-ion batteries, face the issue of swelling due to overcharge conditions when kept on a charger for too long, leading to potential fires, damage, and safety hazards, as current charger and fuel gauge technologies do not effectively prevent continuous charging from causing battery damage.
Innovation Solution
A system utilizing a microcontroller unit (MCU) with a bit array to monitor battery voltage against a predefined threshold, shifting bits to create a sliding window, and stepping down the charger voltage when the battery is near full charge to prevent overcharging, thereby reducing the risk of battery swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery is kept on a charger for too long to ensure full charging, then the charge level is improved, but battery swelling and safety hazards occur due to overcharge conditions
Solution Approach 1:
The patent implements a feedback mechanism where the MCU continuously monitors battery voltage and compares it against a threshold voltage. When the voltage exceeds the threshold, the system detects the overcharge condition and responds by reducing the charger output voltage from maximum to a step-down voltage, preventing battery swelling while maintaining full charge capability.
Solution Approach 2:
The system dynamically changes the charger output voltage parameter based on battery state. The charger operates at maximum voltage to quickly charge the battery, then automatically switches to a lower step-down voltage when the battery reaches full charge, preventing the harmful effects of prolonged high-voltage charging while ensuring complete charging.
2Productivity
If charger ICs terminate charge current when battery is full, then charging efficiency is improved, but continuous trickle current causes battery swelling
Solution Approach 1:
The MCU provides continuous feedback monitoring of battery voltage even after the charger IC terminates the main charge current. When the battery reaches full charge and the charger switches to trickle charge mode, the MCU detects when the voltage exceeds the threshold and triggers the charger to reduce output voltage, preventing the swelling caused by prolonged trickle charging.
Solution Approach 2:
The system enables the battery charging process to self-regulate. The MCU autonomously monitors battery voltage and automatically controls the charger output voltage without user intervention, switching between maximum and step-down voltages based on real-time battery state, thereby preventing overcharge swelling while maintaining efficient charging.
3Device complexity
If a simple voltage threshold comparison method is used, then device complexity is reduced, but monitoring precision may be insufficient for accurate overcharge detection
Solution Approach 1:
The system uses a fixed threshold voltage parameter that represents the precise point at which the battery reaches full charge. By comparing the dynamically changing battery voltage against this static threshold, the system achieves accurate overcharge detection with simple logic, balancing monitoring precision with minimal device complexity.
Data Source
AI summary
An indexed sequence of bits in a buffer is allocated for tracking a battery charging state. The indexed sequence of bits has a first number of bits. A battery voltage of a rechargeable battery is sampled at a sampling rate. For each sampled battery voltage, the battery voltage is compared with a voltage threshold. A next bit position in the indexed sequence of bits is identified. In accordance with a determination that a comparison result is true, a predefined first value is added to the next bit position. A second number of bits that are filled with the predefined first value is determined. A ratio between the second number and the first number is also determined. In accordance with a determination that the ratio exceeds a threshold step-down ratio, a battery charge voltage is stepped down. The rechargeable battery is charged to a step-down voltage.