Circuit/System Description

The high voltage A4 Hybrid/Electric Vehicle Battery Pack consists of lithium-ion cells. Several cells are welded together in series or parallel, and are called a cell group. The cell groups are electrically joined in series to form the Cell Module Assembly (CMA) also known as a high voltage section battery. Based upon option content, the battery pack may contain up to 24 CMAs. Each CMA is identical, although uniquely serialized, and contains a non-serviceable K112 Hybrid/Electric Vehicle Battery Interface Control Module with wireless transmitter/receiver.

Each K112 Hybrid/Electric Vehicle Battery Interface Control Module communicates wireless with the K291 Hybrid Electric Vehicle Battery Pack Communication Module which is also located within the battery pack.

Also located within the A4 Hybrid/Electric Vehicle Battery Pack, the A28 Hybrid/Electric Vehicle Battery Disconnect Relay assembly contains all ten high voltage contactors, and two single-use High Voltage cut-off actuators. To monitor and control the high voltage contactors and associated sensors the A28 Hybrid/Electric Vehicle Battery Disconnect Relay assembly also contains an internal micro-processor that communicates it's status to the K291 Hybrid/Electric Vehicle Battery Pack Communications Module. The communication between the K29 Hybrid/Electric Vehicle Battery Pack Communications Module and the A28 Hybrid/Electric Vehicle Battery Disconnect Relay assembly occurs over a pair of private CAN bus circuits.

The K291 Hybrid Electric Vehicle Battery Pack Communication Module in turn communicates with the vehicle mounted K16A Battery Energy Control Module 1 (BECM) via wired communication circuits. The K16A BECM is the host controller for all battery diagnostics and system status.

The A28 Hybrid/Electric Vehicle Battery Disconnect Relay assembly, also referred to as the Hybrid/Electric Vehicle Battery Cut-Off Actuator, is supplied 5.5V on circuit 10904 by the K291 Hybrid/Electric Vehicle Battery Pack Communications Module.