Series Battery Pack Cut-Off Layout for Soft Pack Overcharge Safety
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Solution Overview
Problem
Soft pack batteries are susceptible to overcharging, leading to thermal runaway and safety risks due to the lack of a high-strength casing and reliable protection mechanisms, which is exacerbated by the reliance on control circuit boards that are costly and unreliable.
Innovation Solution
A battery pack design that includes a first cell with a built-in current cut-off device and a second cell without a current cut-off device, connected in series, where the first cell's current cut-off device interrupts the circuit when it reaches a failure voltage, thereby preventing overcharging of the second cell, which may be a soft pack battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a control circuit board is used to monitor charging parameters and stop charging when overcharging is detected, then overcharging protection is provided, but the cost increases and reliability decreases
Solution Approach 1:
The invention extracts the safety protection function from the soft pack battery itself and transfers it to a separate first battery cell. The first cell is equipped with a current cut-off device that physically interrupts the circuit when overcharging is detected, while the second cell (soft pack battery) relies on this external protection mechanism rather than having its own complex control circuit board.
Solution Approach 2:
The first battery cell acts as an intermediary protection device between the charging source and the second soft pack battery cell. It monitors charging parameters and interrupts the charging circuit when overcharging conditions are detected, thereby protecting the second cell without requiring the second cell to have its own control circuit board.
2Reliability
If a mechanical safety device is equipped in soft pack batteries, then safety protection is improved, but the battery structure becomes more complex and costly
Solution Approach 1:
The invention removes the requirement for mechanical safety devices from the soft pack battery structure itself. Instead, safety protection is achieved through an electrical current cut-off device in a separate first battery cell, which interrupts the charging circuit when overcharging is detected, thereby protecting the second soft pack cell without adding mechanical complexity to it.
3Power
If soft pack batteries are used to achieve high energy retention and low temperature rise, then discharge performance is improved, but safety risks increase due to susceptibility to overcharging
Solution Approach 1:
The first battery cell serves as an intermediary protection mechanism that safeguards the second soft pack battery cell from overcharging. The second cell maintains its advantages of high energy retention and low temperature rise during discharge, while the first cell's current cut-off device prevents overcharging by interrupting the charging circuit when voltage thresholds are exceeded.
Data Source
AI summary
A battery pack, comprising a first cell and a second cell connected in series, the first cell having a current cut-off device and having a first failure voltage, the current cut-off device being configured to be able to break a circuit in response to a voltage value of the first cell reaching or exceeding the first failure voltage, and the second cell having no current cut-off device. The battery pack may use a soft pack battery as the second cell, having advantages such as high energy density, low impedance, high discharge power, a low rate of temperature rise during high-rate discharge, and flexibility in dimensions.