Embracing Standards for Battery Pack Monitoring and Interoperability: The Case for CAN and NMEA 2000 Interfaces on Battery Packs

Embracing Standards for Battery Pack Monitoring and Interoperability: The Case for CAN and NMEA 2000 Interfaces on Battery Packs

As electric propulsion systems gain traction in the marine industry, the need for efficient and reliable battery power sources has become paramount. LiFePO4 (Lithium Iron Phosphate or LFP) batteries have emerged as a popular choice for marine applications, offering high energy density, long cycle life, and inherent safety features. However, with larger battery capacities, for example above 10 kWh, the need for a standard serial interface to monitor and manage their current state and history becomes increasingly important.

Integrated battery management systems (BMS) within LFP batteries are standard. This is because the individual cells as well as the overall pack, need monitoring and active management. When the BMS shares its status over a serial interface, it allows for monitoring of essential battery parameters. Additionally, when BMS configuration can be performed over this interface, it allows for battery packs to be scaled up and managed together.

Adopting a standard interface for BMS’ used in LFP packs would significantly improve the industry’s ability to improve system scalability, performance, reliability, and integration with other onboard systems. Using a standard interface would more easily enable external equipment such as multifunction displays (MFDs) to display and track battery-related information like total cycle count, under-voltage limits, and over-current limits. This information is important for maintaining battery health and preventing equipment failures.

Leveraging the CAN serial bus, or the NMEA 2000 standard for serial interfaces in marine LFP batteries, would help the industry overall. Manufacturers could standardize the information reported and system integrators and boat builders would be assured of compatibility of the physical interface across different devices, as well as being assured of having the core message set of commonly needed parameters in these batteries.

NMEA 2000 is a widely adopted marine networking standard and could be an excellent choice for larger marine LFP packs. It is based on the CAN (Controller Area Network) physical layer and J1939 messaging standards, and offers a robust, time-tested design that is well-suited for the challenging marine environment. Moreover, it enables straight forward integration between equipment from different manufacturers, making it easier for system integrators and boat owners to build and maintain their onboard electric power systems.

This common protocol also enables improved scalability. Larger battery banks can be more easily assembled or chained together to create substantial power systems suitable for electric propulsion. This scalability supports the growth and adoption of electric sailboats and other electric vessels, fostering a cleaner and more sustainable future for the marine industry.

Having a standardized framework for data communication among marine devices, allowing for more effective monitoring and management of LFP batteries and other onboard systems. Adopting a standard serial interface would contribute to the overall health of the industry.

As the marine industry continues to embrace electric propulsion systems and LFP batteries, incorporating a standard serial interface such as NMEA 2000 would help ensure easier adoption, improve safety, and ease integration with other onboard systems. Standards help facilitate interoperability between different manufacturers’ equipment. Having this would support the assembly of larger battery banks for electric propulsion systems. LFP pack manufactures should be encouraged to use BMSs that use these common serial interfaces, which will enhance safety, efficiency, and sustainability in the rapidly evolving world of marine electric propulsion.

Walt White

Founder and lead systems engineer, working to bring new products to market that make a positive impact to the environment. Our products and services help boats make the switch to battery electric propulsion, harness renewable energy, and solve other challenges involving marine electric propulsion systems.

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