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The cells provided by A123 do not have any fusing built into the cells. In order to implement cell-level fusing,
individual cell fusing can be accomplished by constricting the interconnecting metal material near the cell terminal.
For the AMP20 cells this is done by stamping out a pattern of holes in the tabs. Some experimentation and
modeling is required to find the right pattern to offer the proper protection and coordination with the entire
system. A123 uses the following pattern shown in Figure 17 in the tabs of cells integrated into its modules:
Figure 17 – Example AMP20 cell fuse pattern in cell terminals
The fuse pattern shown in Figure 17, stamped into 0.2 mm copper, clears in approximately one second while
carrying 1800 A. This and possible alternative designs should be verified using modeling software and bench
testing prior to design release.
For cylindrical cells, the straps welded to the end caps can be necked down to act as a fuse. In Figure 18, the 7 mil
nickel strap material is necked down to 3.6 mm, and clears at approximately 2100 A in 0.1 second. This and
alternative designs should be verified using modeling software and bench testing prior to design release.
Figure 18 – Example of a necked-down connection to the cell which can act as a fuse
To prevent ignition of the hot vented gasses during a simultaneous fusing and venting
incident, place the fused tab on the opposite side of the outside casing where the vent is
located. In the A123 ANR26650 cells, the vent is located on the positive terminal.
