Battery Pack Selector Switches for Voltage Drop Reduction
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Solution Overview
Problem
Traditional dual battery pack systems for portable electronic devices incur additional costs and power dissipation due to discrete MOSFET switches on the system side, leading to reduced runtime and increased voltage drops, which adversely affect battery life.
Innovation Solution
The system relocates sole selector switches within the battery packs, using a status function circuit and mode function circuitry controlled by a host processor to manage power sequencing and switching, eliminating the need for MOSFET switches on the system electronics side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If discrete MOSFET switches are used on the system side to implement the selector function, then the switching between battery packs is enabled, but additional voltage drop and power dissipation occur, reducing runtime
Solution Approach 1:
The selector switch function is extracted from the system side and relocated to the battery pack side. Each battery pack contains its own MOSFET switches that directly connect its cells to the pack positive terminal, eliminating the need for additional MOSFETs on the system side and reducing the number of switching components in the power path.
Solution Approach 2:
The selector switch function is merged with the battery pack protection and control circuitry. The pack control unit now directly manages the MOSFET switches within each pack, combining the selection, protection, and power management functions into a single integrated location at the battery pack level.
2Ease of operation
If discrete MOSFET switches are used on the system side, then battery pack selection is achieved, but additional costs are incurred
Solution Approach 1:
The MOSFET switch array is extracted from the system electronics and placed within the battery packs. This removes the need for complex system-side switch management circuitry and reduces the bill of materials for the system electronics while distributing the control functionality to the battery packs.
Solution Approach 2:
Each battery pack becomes self-sufficient with its own integrated MOSFET switches and control logic. The pack control units independently manage their respective switches without requiring complex coordination circuitry in the system electronics, simplifying the overall system architecture.
Data Source
AI summary
A system interface having an interface for dual battery packs provides for power up sequencing of battery packs and pack switching under the control of a host processor within associated system electronics. The host processor communicates with each battery pack via a pack interface that includes a single wire mode control signal and a single wire status signal. The mode control signal allows the host processor to control the operational mode of selector switches within the respective battery pack. The single wire status signal provides status information to the host processor regarding the state of the selector switches within the respective battery pack. The mode and status signals are multi-state signals that permit at least three states to be identified via the single wire interface. Selector switches are provided only in the battery packs. No selector switches are included in the system electronics to minimize voltage drops between the selected battery pack and the system electronics.