Pack Enclosure

A battery pack enclosure can be in many forms depending on the application. We can break down the functions of the enclosure into these headings:

  • Mechanical
  • Electrical
  • Thermal
  • Safety
  • Manufacture
  • Transport
  • 4R’s

This just allows us to think about the requirements for the enclosure in a number of ways, some will overlap, but that is fine.

Mechanical

  • Mechanical location
  • Sealing / Ingress Protection
    • IP Rating system consists of two digits. The first digit represents the degree of protection against the intrusion of solid objects, while the second digit represents the degree of protection against the intrusion of liquids.
    • Seal design
  • Crash protection
  • Crush protection
  • Material selection – there are many different materials used in battery pack enclosures.
  • Vibration Isolation

Electrical

  • HV protection
  • HV isolation
    • Creepage and Clearance – High voltage circuits can discharge across a gap, the gap can be through the air or across a surface. Hence it is important to design to the correct standards.
  • EMC shield

Thermal

  • Environmental thermal isolation – how well is the battery pack isolated from the environment, does the heating and cooling of it require lots of energy as it gets lost to the atmosphere?

Safety

  • Containment of gases emitted by cells
    • Pressure Equalization vs. Pressure Relief – Pressure equalization, commonly referred to as “breathing,” aims to maintain pressure balance within a battery enclosure due to environmental or elevation changes.
  • Containment of fire in case of thermal runaway
  • Electrical Protection

Manufacture

  • Location and orientation of base
  • Frame assembly
  • Seal application
  • Sealing testing
  • Labelling – a battery pack needs labels that define what it is and warnings about it’s safe handling and use. The requirements are market and pack type dependent.

Transport

  • Safe transport enclosure

4R’s

  • Accessible for repairs
  • Safe transport and handling
  • Ease of dismantling for recycling