E-Mobility Engineering 014 l InoBat Auto dossier l In Conversation: Brandon Fisher l Battery monitoring focus l Supercapacitor applications insight l Green-G ecarry digest l Lithium-sulphur batteries insight l Cell-to-pack batteries focus

core. The chip sits on a prismatic or pouch battery cell to monitor the current, voltage and temperature. All the data is stored on the chip, providing a full history of the activity of the cell and calculating the state of health and state of charge using a specialist digital signal processor. This reduces the amount of data that needs to be transferred to the BMS. The specification of the flash memory in the process technology is a key point. The aim is to store the data reliably in this hostile environment so that there is a record of the charging cycles throughout the life of the cells. This data is transferred back to the BMS via a near field comms (NFC) wireless link on the chip, similar to the NFC link used in a bank payment card. An NFC antenna on the chip couples over a distance of a few millimetres to a single cable that runs the length of the battery pack and acts as the receiver. This eliminates the wiring harness usually required for the BMS, and reduces the number of components and the weight, and boosts the reliability. It also avoids the risk of wireless data being intercepted from outside the battery pack. The design came about as the result of analysis and benchmarking of other wireless and wired systems, eliminating wires, connectors and high-voltage components. It also allows more flexibility in the system design as every cell, up to 300, connects to the one antenna, all reporting in sequence. That means designers can add one cell at a time, rather than having to add a block of 18 in a module with a monitoring chip, which is currently the way the pack is expanded. This gives more flexibility to designers of systems that may have restricted space for the battery pack. Placement of sensors Being able to capture significant data is the first step for improving the performance of the battery pack. However, it is often not possible to get data from exactly the right place in the pack. This is the case for rechargeable batteries, where there is limited visibility of temperature and pressure during the testing of the cells. Thin foil sensors can be placed between the cells to solve this issue. During the charge-discharge cycle, batteries undergo continuous volume Adding processing to the battery monitoring chip allows data on cell activity to be stored (Courtesy of Dukosi) A monitoring system with a single antenna reduces the weight of the battery pack (Courtesy of Dukosi) 38 Summer 2022 | E-Mobility Engineering