Battery Pack Design Challenges

Battery Pack Design Challenges

A battery pack is a collection of battery cells – or groups of them – in series and parallel to achieve the required voltage and energy capacity. They are assembled into serviceable units for use in applications like electric vehicles or industrial equipment. They typically also contain a battery management system (BMS) software and may include cooling and heating systems, depending on the application.

Batteries have many different combinations of electrode materials that can be used to achieve a variety of performance and specification trade-offs. The most common chemistry is lithium-ion, but nickel-metal hydride (NiMH) and lithium polymer are also available.

Cells are stacked and soldered together to make a module. Multiple modules are then assembled into a battery pack using a combination of mechanical and electrical connectors. The battery management system (BMS) controls the flow of current through the pack, ensuring it stays within safe operating parameters. A BMS can also be programmed to shut off a battery pack in the event of a failure.

There are a number of design challenges that must be addressed when engineering a battery pack. One is vibration isolation. Batteries in moving applications such as electric vehicles can transmit unwanted mechanical loads that can cause premature damage to the internal components of the battery.

Other key issues are functional safety and life span/reliability. The former includes ensuring that all the individual batteries in a battery pack are only ever used within their declared SOA (state of a charge) requirements. This delicate oversight is necessary to prevent over-charging and under-discharge that could lead to fire, injury or equipment loss.

The latter involves active and passive thermal protection. Passive measures such as insulating the battery pack and adding cooling systems are vital to maintaining safe operation. Active temperature control enables the battery to operate at its optimum performance over a wide temperature range.

Lastly, there are a number of other design challenges that can impact the long-term reliability and performance of battery packs. Those challenges include the use of non-compatible chemistries, fast charge cycling and battery ageing. Battery pack engineers are continually working to improve battery management systems in order to mitigate these effects and extend battery lifespans.