Performance Composites manufactured the composite battery enclosure for an all-electric bus.
Performance Composites was hired by an electric bus manufacturer and a 1st tier Automotive OEM engineering design firm to develop and manufacture a composite battery enclosure (approx.. 40” x 60” x 8”). The design had multiple criteria: must support 900 lbs of batteries and electronics, sustain 20G shock load, be water tight, surpass salt spray corrosion test, prevent road hazard from penetrating into the batteries, be Class 1 fire retardant and be very light weight (<80 lbs) - all while meeting an aggressive cost target.
Composite material was the ideal choice for this application and was the only material that met all of the requirements. Performance Composite engineers worked closely with the customer’s design team to develop the battery enclosure. We spent a lot of time on the structural design so the enclosure could meet the load specification and also secure the batteries and components inside the enclosure. The enclosure was comprised of a hybrid sandwich construction consisting of biaxial fiberglass fabric, balsa core and Kevlar fabric. Proprietary insert design was used at high load points. We use the vacuum infusion process (VIP) for this enclosure - the ideal process for this application. VIP allowed us to achieve very high fiber content (>65% by weight), which resulted in an enclosure with high strength and stiffness at minimum weight. We manufactured matched inner and outer molds that were vacuum sealed. The molds allowed us to create class A surfaces on all sides and control the tolerances of the key interfaces.
After the design was finalized, Performance Composites crafted five prototype enclosures that were subjected to testing and fit up. Based on the testing and the fit up, a few minor design changes made, and we fabricated the production tooling and manufactured the first article enclosures. The first article units went through the PPAP quality process and passed the life cycle testing at Altoona track testing. We are currently in full production of these enclosures.