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 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 monitors the temperature, current and voltage of its respective cell groups. Each K112 Hybrid/Electric Vehicle Battery Interface Control Module is also responsible for balancing the voltage of each cell group via internal resistance circuits. 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. The K291 Hybrid Electric Vehicle Battery Pack Communication Module in turn communicates with the vehicle mounted K16A Battery Energy Control Module (BECM) via wired communication circuits. The K16A BECM is the host controller for all battery diagnostics and system status.

The K291 Hybrid Electric Vehicle Battery Pack Communication Module also contains internal sensors to monitor the A4 Hybrid/Electric Vehicle Battery Pack for thermal propagation. The sensors monitor for internal temperature, pressure and off-gassing.

If the K16A Battery Energy Control Module observes several indications that thermal propagation has begun, this DTC is set.