Refinement of the raw materials, through cell assembly and finally to battery pack the manufacturing process is complex and requires a broad range of skills.

Cell Manufacturing

A huge subject and hence a dedicated area to look at the stages, chemistry, costs and future direction.

cell manufacture schematic

Cell Manufacturing Process

In order to engineer a battery pack it is important to understand the fundamental building blocks, including the battery cell manufacturing process. This will allow you to understand some of the limitations of the cells and differences between batches of cells. Or at least understand where these may arise.

Cell Testing

When assembling cells into a module, pack or directly into a product there are a number of tests that need to be done to ensure quality control.

What level of cell matching do you do prior to assembling a battery pack? Assuming the battery pack will be balanced the first time it is charged and in use. Also, assuming the cells are assembled in series.

  1. none, force the cell supplier to deliver cells matched to within +/-0.02V
  2. none, gross balance the pack during first charge once built
  3. preselect and group cells prior to build
  4. pre-charge/discharge all in-coming cells to a set voltage/SOC
  5. average-balance cells in parallel group prior to building in series
  6. average top-balance cells in parallel group prior to building in series

Module Manufacture

There are 7 Steps in the Module Production Process:

  1. Incoming Cells Inspection
  2. Preassembly
  3. Stacked Cells Tightening/loading with End Plates
  4. Connecting the Cells inside the Module
  5. Mounting of the BMS Cell Sensing Circuit (CSC)
  6. Cell Stack is Loaded into Module Housing
  7. End of Line Testing and Quality Control of the Module

Pack Manufacture

Battery Pack Assembly Bill of Process

A generic battery pack assembly bill of process that lays out the significant steps and challenges.

Battery Assembly Times: A look at battery assembly times based on available reports and data.

The application of thermal interface materials is also an important consideration in manufacturing as this pattern can result in non-uniform or even voids in the TIM.