To improve the performance and longevity of our battery pack I designed
an integrated convection cooling system by flowing ambient air over the busbars of our battery pack.
The design intends to cool the busbars as well as the "PCM" or "Power Control Module" which steps
the 400V pack down to 24V to run the LV bus on our car. The PCM is located in the front ancillary area
shown in the photo. Small vents were placed at the front corners of the pack to allow air to flow over
the busbars and down through the ancillary area before it flows out of the pack.
The accumulator (Battery Pack) has 6 segments that are connected in series. To avoid
differences between the segments and cells the design had to cool the segments uniformly. From previous analysis
we knew needed a minimum of 30CFM to flow through the accumulator at approximately 50Pa. We also had previously set
an ingress protection rating of IP54 as a standard for any vents on the accumulator.
Mounting this project was specifically difficult. The accumulator and chassis designs had already
been finalized before the start of this design, and there were no fans with the required fan curve that could fit
on the pack during installation into the chassis. This is problematic as the battery pack is removed often for charging
and repairs. I came up with a system in which the fan module would be tucked into the chassis before the pack was installed
and fastened in place afterwards. This drove me to choose to mount threaded studs onto the pack and have the mounting screws
drop in vertically where we would actually have room to fit a wrench. The final part also contains alignment features to make
the on-car installation easier.
The plan was to 3D print the part since it had highly complex geometry,
would see little load, and needed to remain lightweight. During the installation there is
a high likelihood of hitting or pinching the module so we decided to do a SLA resin print
to increase the overall rigidity of the part.
