Innovative battery status monitoring for electric vehicles (EVs)

19 January 2024

Metis Engineering has launched the new and advanced Cell Guard for the state-of-the-art battery monitoring system in electric vehicles.

The innovative battery safety sensor aims to revolutionize battery status monitoring for electric vehicles (EVs) and energy storage systems (ESS).

Cell Guard is a unique sensor that provides accurate and detailed information about the health status of lithium-ion batteries, enhancing their longevity. It can also detect cell venting, an early sign of catastrophic battery failure, significantly reducing the risk of thermal runaway.

Unlike current battery cell monitoring systems (BMS), which typically offer only temperature and voltage sensors, Cell Guard monitors a range of environmental parameters necessary to ensure the battery continues to operate under optimal conditions. This includes Volatile Organic Compounds (VOC), pressure variation, humidity, dew point, and an optional accelerometer to record impact loads.

These data can be cross-referenced with other inputs, such as cell temperatures and pressure spikes, to identify cell venting. The sensor transmits data via a configurable CAN interface to a control unit, such as the vehicle's ECU. This can then generate an alert to notify the driver within seconds that cell venting has occurred. The sensor can also initiate the process to cut off the battery pack circuit, allowing it to cool down and prevent thermal leakage.

Cell Guard's accelerometer can monitor impact loads up to 24 G and the impact duration the battery pack may experience, reducing costly scrap. This information can revolutionize the used electric vehicle resale market, offering buyers the necessary clarity to make informed decisions about the battery pack's condition and maintenance. It can also provide a much broader view of the battery's condition for reuse, recycling, and potential insurance claims.

Additionally, Cell Guard can monitor the dew point in the battery pack and trigger an alert before condensation deposits on the battery terminals, which could cause short circuits and thermal incidents.

The sensor also features a programmable pin that can control the relay if a threshold is reached. The sensor has a low-power mode that silently continues to monitor the pack. If a threshold is reached, the sensor starts transmitting on CAN, meaning it can wake up a vehicle in case of a detected issue.

Limitations of Current Battery Management Systems

While electric vehicle battery packs already have a Battery Management System (BMS), this system may have limitations in monitoring the battery pack's health. For example, temperature sensors may only be present for a few cells, making it difficult to detect issues promptly. Detecting cell problems through voltage fluctuations can also be challenging in the short term because other cells in parallel can support the voltage, masking issues with a single cell. Cell Guard can overcome this limitation by integrating with the BMS, providing more detailed information about the health of individual cells.

Certified according to automotive ISO standards, Cell Guard is manufactured in the UK under stringent quality control conditions to meet the orders of a rapidly growing number of OEMs and Tier 1 where they are used in ASIL B applications.

With Cell Guard, Metis Engineering is setting a new standard for advanced battery status monitoring in electric vehicles and energy storage systems. Enhancing safety, reducing risks, and providing an unparalleled view of battery conditions will provide peace of mind to both electric vehicle drivers and ESS manufacturers, promoting wider adoption of electric vehicles and energy storage systems.

Metis Engineering's sensors are used in a wide range of applications, including Bloodhound LSR, Brompton Bicycles, high-performance electric aircraft, motorsports such as Formula E and World Rally Championship, energy storage systems, and autonomous vehicles.


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+39 02 3340 0846

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