The Sennheiser BA 61 is a high-capacity rechargeable battery pack specifically designed for use with Sennheiser's professional SK 6000 and SK 9000 series bodypack wireless transmitters. It provides a reliable and cost-effective power solution, eliminating the waste and ongoing expense of disposable AA batteries. The battery pack is based on Nickel-Metal Hydride (NiMH) technology, offering a stable voltage discharge curve that is ideal for wireless transmitters, ensuring consistent audio performance throughout its charge cycle. It is designed to slide into the battery compartment of the compatible transmitter just like a standard AA battery sled.

The BA 61 typically features a built-in charging circuit, allowing it to be recharged using Sennheiser's designated charging stations (like the L 6000) or a compatible external charger. This integrated charging capability simplifies the workflow for broadcast, theater, and film sound teams, who can maintain a fleet of charged batteries ready for use. By adopting rechargeable battery packs, users benefit from reduced operational costs, less environmental impact, and the convenience of knowing their power source is fresh and reliable for every show or shoot.