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New Circuit Tech Offers Advantages for EV Battery Packs

May 03, 2024 by Jake Hertz

Ennovi’s flexible die-cut circuit technology enables low-voltage connectivity in EV battery cell contacting systems.

Batteries are indispensable in modern society due to their versatility. Flexible printed circuits (FPCs) facilitate the interconnection of battery cells, control modules, and sensing components within battery systems. However, challenges like scalability, material limitations, and production complexities in FPC manufacturing have created a need for alternate solutions.

To address these challenges, Ennovi has introduced its automotive-grade flexible die-cut circuit (FDC) technology for sustainable wiring in automotive battery designs.

 

Electric vehicle battery pack

Electric vehicle battery pack. Image used courtesy of Ennovi

 

Flexible Printed Circuits in Batteries

In power battery applications, the FPC primarily substitutes traditional wiring harnesses within the battery pack to provide electrical interconnection between various components.

FPCs provide a flexible, compact solution for routing power and signals between battery cells, management systems, and external connectors. In EVs, FPCs streamline part count and assembly time, enhancing efficiency during build processes. Additionally, FPCs are advantageous in these applications due to their light weight, thin profile, and ability to conform to irregular shapes within the battery pack. In this way, they ensure reliable electrical connections while minimizing space and weight, ultimately contributing to the battery system's overall efficiency, form factor, performance, and safety.

Although FPCs are extensively used in battery systems to replace wire harnesses, they represent the most costly element within the current collector assembly. This high-cost factor overshadows the weight reduction benefit of FPCs, particularly in EVs. 

Additionally, the complexity of the manufacturing process is another barrier to adoption. Typically, FPCs are crafted through a multi-stage, batch photolithography process for copper trace etching in the flexible circuit. This production method involves corrosive chemicals to dissolve surplus copper, alongside considerable time and energy for waste copper extraction, posing challenges for efficient recycling.

 

A New Era of Battery Connectivity

Ennovi’s FDC technology aims to improve EV battery cell contacting systems, featuring a flexible flat device comprising copper traces produced via a sustainable continuous die-cut process. 

 

Ennovi’s FPC connection.

Ennovi’s FPC connection. Image used courtesy of Ennovi

 

Traditional FPCs pose cost and sustainability challenges due to their complex manufacturing process. In contrast, Ennovi's FDC technology offers a more cost-effective and eco-friendly alternative due to its fewer manufacturing steps (50% reduction), environmentally friendly materials, and faster production.

Unlike FPCs, which are limited to 600 x 600 mm in size, FDCs have no length restrictions since they are manufactured reel-to-reel. With certain design considerations, FDCs offer comparable performance to FPCs. 

 

Ennovi’s FDC technology is portrayed.

Ennovi’s FDC technology is portrayed. Image used courtesy of Ennovi 

 

According to the company, the FDC technology makes it possible to achieve cost savings ranging from 25% to 50% without sacrificing technical capabilities. Additionally, Ennovi’s FDC claims to prioritize sustainability through a recyclable process enabling the recycling of clean copper waste material.

These findings were validated through comprehensive in-house testing, including dimension, thermal shock, trace resistance, temperature rise, insulation resistance, and high voltage tests.  

 

EV Improvements on the Road Ahead

With potential cost savings and no length restrictions, Ennovi’s FDCs promise an alternative to FPCs to ensure lighter and more compact EV solutions. The results should be immediately tangible, as lighter vehicles offer greater range. The assembly simplicity of FDCs, as opposed to wiring harnesses, means decreased cost and improved vehicle reliability. Should this technology find its way into mainstream adoption, the EV industry could stand to realize notable benefits.