Backpack Battery Pack Thermal Management via Segmented Cell Retainers
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Solution Overview
Problem
Battery packs used in power tools and outdoor equipment face challenges such as thermal management, cell degradation, and failure due to uneven cooling and potential for thermal runaway, especially in harsh environments, which can lead to decreased performance or total failure.
Innovation Solution
A backpack battery system with a thermal management system that includes a cell retainer assembly with airflow channels and internal fuses to ensure consistent cooling and prevent thermal damage, along with an electrically symmetrical cell connector to balance current paths and protect against cell failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If battery cells are arranged together in a battery pack to achieve desired output characteristics, then the power and energy capacity are improved, but thermal management becomes more difficult and thermal runaway risk increases
Solution Approach 1:
The battery pack is divided into multiple cell groups with individual retainer assemblies for each group. Each retainer assembly independently manages thermal characteristics of its associated cell group, allowing localized thermal control rather than treating the entire pack as a single thermal zone.
Solution Approach 2:
Cell retainer assemblies serve as intermediary structures between battery cells and the external environment. These retainers provide thermal management functions by facilitating heat dissipation pathways while physically supporting and electrically connecting the cells.
2Adaptability or versatility
If battery cells are operated in harsh environments, then the versatility and adaptability are improved, but the reliability and performance stability deteriorate
Solution Approach 1:
Different portions of the battery pack structure are given different properties - cell retainer assemblies provide mechanical support and thermal management, while cell group connectors provide electrical connection and additional structural support. Each component is optimized for its specific function while contributing to overall environmental resilience.
3Reliability
If one cell deteriorates or fails, then the battery pack may reach full charge before other cells, but this creates high temperature and pressure stresses that worsen the failure condition
Solution Approach 1:
Cell retainer assemblies are designed to detect and respond to cell deterioration before it leads to catastrophic failure. The retainers provide mechanical constraints and thermal management that cushion against the effects of cell degradation, preventing runaway conditions.
Solution Approach 2:
The cell retainer assemblies monitor cell conditions and adjust thermal management accordingly. When cell deterioration is detected through changes in electrical or thermal characteristics, the retainer structure facilitates heat dissipation to prevent thermal runaway.
4Power
If cells are connected in parallel groups, then the current capacity is improved, but the risk of high-rate discharge through failed cells increases
Solution Approach 1:
Parallel-connected cells are grouped into separate cell groups, each with its own retainer assembly and connector. This segmentation isolates potential failure modes within individual groups, preventing a single failed cell from affecting the entire parallel bank.
Solution Approach 2:
The cell retainer assembly extracts and removes heat from cell groups, particularly from cells that may be deteriorating or have failed. By actively managing thermal characteristics at the cell group level, the system prevents thermal stress from propagating through the entire battery pack.
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
The system improves battery pack performance by maintaining consistent cooling, preventing thermal damage, and ensuring safe operation by isolating faulty cells, thus enhancing the robustness and reliability of battery packs in inhospitable environments.
Implementation Method 1
a first cell retainer assembly and a second cell retainer assembly of the plurality of cell retainer assemblies. Each cell retainer assembly includes a plurality of cell reception slots configured to conform to an outer shape of respective ones of the battery cells so as to hold the battery cells in the cell reception slots. The cell retainer assemblies are configured to define a plurality of airflow channels between adjacent ones of the battery cells so as to facilitate cooling of the battery cells
Implementation Method 2
The cell retainer assemblies are configured to define a plurality of airflow channels between adjacent ones of the battery cells so as to facilitate cooling of the battery cells
Implementation Method 3
The connector includes a first body portion and a second body portion, the first body portion and the second body portion each having a substantially uniform cross-sectional area. The connector includes at least one fuse element extending between the first body portion and the second body portion, the at least one fuse element having a smaller cross-sectional area than the first body portion and the second body portion
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A cell housing, such as for a backpack battery pack, includes a first wall, a second wall, and a cell retention structure there-between, wherein the cell retention structure is configured to retain battery cells arranged in a matrix of rows and columns such that the longitudinal axis of each battery cell is substantially parallel to the longitudinal axes of the other battery cells. A plurality of connectors are located on the exterior of the cell housing and are electrically connected to the battery cells through openings in the first and second walls of the cell housing. The connectors electrically connect the cells in each row in parallel and the cells in each column in series. The connectors may comprise unitary connectors that electrically connect the positive terminals of at least two cells of one row of cells to each other and also to the negative terminals of at least two cells of another row of cells. At least one fuse may be disposed in the connectors electrically between at least one cell and a plurality of the other connected cells. A relay may be connected in series between a printed circuit board and the battery cells to disconnect the cells from the load upon the occurrence of a predetermined event.