DEV1 Battery Pack Assembly

With DEV1 assembly close to completion, the battery packs have been built! Module components were printed, cells welded and busbars bolted in place, it was fantastic to see the assembly take form.

The team first assembled sub-modules that provided a substrate for cell positioning within the pack. This enabled a multi-step assembly process, decoupling the pack structure manufacturing process from the cell module manufacturing process allowing us to build components in parallel.

Sub-Module Assembly

Custom jigs were designed to fixture assemblies. See above team members Ryan Bliss and Alex Klimecky use a two-part thixotropic epoxy to construct the sub-modules.

Sub-Module Symmetry

Each sub-module was checked for symmetry after having cured in the fixtures. It was important to have dimensional consistency, ensuring proper spot welds.

Thermistor Installation

Thermistor were placed throughout the module on the mid-point of the cell casing. Placement was prioritized near the top of the pack to account for potential elevated from current imbalance.

---

After sub-modules were built, we proceeded to module and pack assembly. Sub-modules were aligned with bulkheads that index with slots in the powder coated aluminum pack structure. Bulkhead geometry included a mount location for busbar alignment and thermistor and balance wire routing. Once BMS electronics have been fully validated, they will be installed on the top bulkhead.

Module to Pack

Modules were assembled outside of the powder coated aluminum structure. See in the photo a partially assembled packs and un-welded module.

Side Profile

Thermal interface pads were placed between the cells and pack enclosure. This promoted heat transfer from the cell ends and nickel current collectors while also dampening vibrations induced on the module.

Nickel to Copper

From a perspective of ampacity, we elected to use copper for our primary busbar. To promote a proper weld with our copper, we sent busbars out to be nickel plated. This photos shows the numerous spot welds used to connect the current collectors with our primary busbar.

Spot Welding

Team member LJ Boone is seen spot welding. Modules were placed within the pack structure for welding.

Fully Welded Pack

Depicted is a fully assembled module with additional busbar assemblies in the background ready for the remaining packs.

A short time-lapse of spot welding cells.

---

Now that cells were welded, the remaining heat transfer pad was placed and plates were bolted on. From the top of the module BMS data connection along with an internal fuse was placed. Following assembly we wanted to have some fun and test out our new packs. Time to bring out the go-kart! But first a brief charge to bring them up to voltage…

Nominal Voltage

Checking nominal voltage of the pack after welding.

First Charge

Using a MagnaPower DC supply to charge packs at roughly 1kW.

Makeshift Battery Mount

To start testing we developed a quick mounting solution.

After a short charge, we attached cells to the back of our go-kart and began to drive around the parking lot. EVT’s go-kart draws significantly less current than DEV1’s Emsiso Inverter and Emrax 188, as such pack surface temperatures were roughly ambient air temp.

Driving around RIT’s parking lot ⚡️

It was incredibly fun to design and build the battery packs for DEV1! I absolutely couldn't have done it without the help of many on the team! Looking forward to seeing them run on the motorbike in the fall!

-Michael Letterio