Battery Enclosure Design
Some battery packs are installed inside the product, and only require a shrink-wrap enclosure. In other cases, battery packs are mounted externally and may serve a mechanical function, such as a handle or base for the product. At the same time the case must also protect the cells and the electronics from the harsh operating environments of temperature extremes, water ingress, humidity and vibration in which these batteries work.
Injection Molded Plastic
Enclosures made from injection molded plastics are most commonly used for battery packs. For these enclosed pack designs, two or more plastic parts are molded and then assembled with the pack and accompanied circuitry. They can be sealed using glue, mechanical fasteners (Screws) or ultrasonic welding. The product cost can be reduced by using insert moldings in which the interconnection strips and the terminals are molded into the plastic parts to eliminate both materials and assembly costs.
Custom Designed Battery Pack Enclosure Made From Injection Molded Plastic
In some designs, the battery pack can form part of the outer case of the end product and usually requires a mechanical latch to hold the battery in place. This latch as well as the terminals must interface with plastic parts from the device itself so high precision and tight tolerances are essential.
Shrink Wrap or Vacuum Formed Plastic
The simplest and least expensive packaging for small batteries is shrink wrap or vacuum formed plastic. These solutions are only possible if the battery is intended to be completely enclosed by the finished product. In other cases, battery packs are mounted externally and may serve a mechanical function, such as a handle or base for the product. Our extensive experience in designing battery enclosures of all types allow us to enhance the functional design of the product while assuring that the battery passes any shock, vibration and environmental testing required for your application.
Thermal effects need to be taken into account and, tolerances must allow for potential swelling of the cells. Some Lithium pouch cells may swell as much as 10% or more over the lifetime of the cell. For this reason, enclosures may be designed with vent holes to dissipate generated heat or exhaust vented gases from cells. Multiple vent holes may be used to increase airflow in and out of the pack.
Intrinsically Safe Batteries
Intrinsically safe batteries will not initiate and explosion should the electronic device malfunction while operating in areas that contain explosive gases or high dust concentration. For these applications, specific materials are selected for battery pack enclosure and many times potting material is used in the battery pack enclosure to eliminate any air gaps.