Battery Pack Cooling System

To improve the performance and longevity of our battery pack, I designed an integrated convection cooling system that flows ambient air over the pack's busbars. It also cools the Power Control Module (PCM), which steps the 400 V pack down to 24 V for the car's low-voltage bus. The PCM sits in the front ancillary area. Small vents at the front corners of the pack let air flow over the busbars and down through the ancillary area before it leaves the pack.

The accumulator has six segments connected in series. To avoid differences between segments and cells, the design had to cool them uniformly. Earlier analysis showed we needed at least 30 CFM at about 50 Pa through the accumulator, and the team had already set IP54 as the standard for any vent on it.

Mounting was the hardest part of this project. The accumulator and chassis designs were already final when I started, and no fan with the required fan curve could stay on the pack while it was installed into the chassis. That matters because the pack comes out often for charging and repairs.

My solution tucks the fan module into the chassis before the pack goes in, then fastens it in place afterward. So I mounted threaded studs on the pack and made the mounting screws drop in vertically, where there is actually room for a wrench. The final part also has alignment features to make installation on the car easier.

The geometry was complex, the part would carry little load, and it needed to stay light, so 3D printing was the plan from the start. Installation brings a high chance of hitting or pinching the module, so we chose an SLA resin print to make the part more rigid overall.