Module Design Sprint - MSXV

Owned by Owen Li
Last updated: Sept 04, 2023 by Kostubh Agarwal
5 min read

Sprint Introduction:

The challenge of this sprint is to create a functioning prototype battery module. Groups will be given a list of design considerations and constraints, the CAD file of the cells, and resources on previous modules. Groups will then complete a prototype module from design to manufacturing. The prototypes do not need to be perfect, the purpose of this sprint is for members to learn about batteries, module design, and general engineering work flow.

MS12 Prototype Module
MS14 Module Rev 1

Design Sprint Goals:

  • Obtain experience of bringing a project from idea to completion.

  • Get accustomed to critiquing each others work

  • Making self-driven decisions throughout the entire process, starting from basic requirements + constraints, to selecting OTS components/materials

  • Getting comfortable with holding each other accountable to our own deadlines.

  • Documenting progress and decisions in a design log

Design Parameters:

Here are some important design considerations: (You may come across more as the sprint goes on).

  • Manufacturability (We should be able to build the prototype in the bay)

  • Module to Module connections (How will the electrical connections between modules look like?)

  • How to hold cells (3D print/ off the shelf)

  • Electrical connection of cells (spot welding?, mechanical assembly?)

  • Electrical Isolation/ HV Safety (Top and bottom plate material, dropping tools in battery box)

  • Mechanical robustness (What happens in the event of crash?)

  • Cooling (How should the module work with air cooling)

  • Mounting (How will the module connect to the enclosure box?)

Specification

Value

Specification

Value

Module Cell Count

4S8P

Module Count

9 Modules

Max Current Draw

78.4A

Cooling Type

Forced Air Cooling

Battery CAD Model (21700)

https://grabcad.com/library/sony-se-us21700vtc6a-4-000-mah-li-ion-rechargeable-battery-1

Initial Chassis CAD

To see how modules should fit into vehicle.

 

Timeline & Deliverables:

Read this before starting for a good introduction to battery module design:

Here is Micah’s PDF library, lots of useful materials for more in depth reading:

Relevant Research

Here is an FAQ on Module Design (Thanks Micah!):

Battery Q&A

ASC 2022 Regulations:

https://www.americansolarchallenge.org/ASC/wp-content/uploads/2022/03/ASC2022-Regs-EXTERNAL-RELEASE-B.pdf

Sample Design Logs:

Battery Box Thermal Analysis - Design Log

Kevin Bui FYDP FDR - Password is “midsun”

Charge Port Mount Design Log

https://drive.google.com/drive/folders/1fCtR9BuxDQ6isJEk4DCbPftVV9Hr1BZh?usp=sharing

 

Phase 1 [Mar 14 - 21; ~1 week] - Review with Micah Black:

  1. Conceptual Design: Rough CAD design, or a “good” hand drawing

    1. Should have a good idea of the arrangement of the cells in the module

    3. Example of a basic CAD model. This model is missing the module to module connections, which should be included in the initial rough cad design.

  2. Connection Types: Decide on what types of mechanical and electrical connections to use in the module between the cells, and between modules as well.

    1. CAD should include a basic model of the electrical connection that you decide on, specific dimensions (width, thickness, etc.) of these connections can be ironed out later

    2. Decide on a busbar material and manufacturing method (How will the busbars be made? Do we have these tools in the bay or machine shop, or will it need to be outsourced to a manufacturer? *For a prototype we should manufacture everything in house)

  3. Design Log: All design decisions, parameters, etc. should be documented in a design log which will be used when presenting during the critique

Phase 2 [Mar 21 - Apr 4; ~2 weeks] - Review with Micah Black:

  1. “Completed” CAD Model: CAD Model should now include all components of the module, BMS connections, top and bottom plates, thermistor placements, fasteners, electrical isolation covers, gusset plates, etc.

  2. Reasonable Dimensions: Dimensions should no longer be rough

    1. Should have some kind of reasoning behind the dimensions of busbars and electrical connections

  3. Part Selection: Decide on materials and component types for everything in the module. Suppliers don’t need to be finalized here, but an idea of what kind of fastener to use for the mechanical connections, or what material to manufacture the plates out of should be picked.

  4. Design Log: All design decisions, parameters, etc. should be documented in a design log which will be used when presenting during the critique

Phase 3 [Apr 4 - May 9; ~4 weeks] - Review with Micah Black, and former Battery Leads:

  1. Completed Module Revision 2: The feedback accumulated from Phase 2 should be implemented into the design

  2. Design Log: All design decisions, parameters, feedback etc. should be documented in a design log which will be used when presenting during the critique

Phase 4 [May 9 - June 6; ~4 weeks] - Manufacturing of Prototype:

  1. Final Design and Manufacturing: Feedback from Phase 3 should be implemented and the finalized designs should then be manufactured.

  2. Last Minute Changes: Groups will likely run into design errors in manufacturing, that is totally okay. This project is for the team to learn and gain experience. Groups may need to change their design and remanufacture in this phase, make sure to document any changes you made during this process

  3. Design Log: Manufacturing process, issues encountered and solutions should all be documented.

Phase 4 and beyond:

These will be finalized later on, but we will run some tests on modules using older cells and look at some different metrics:

  • Extra weight (cell weight/ total weight)

  • Volume

  • Manufacturability

  • Temperature (inaccurate)