Building Connectivity for More Powerful EV Batteries

Advances in battery performance have helped electric vehicles (EVs) become the fastest growing segment in the automotive industry in recent years, taking more market share away from internal combustion engine (ICE) vehicles. With the improved range and performance of today’s EVs, sales doubled in 2021 and are expected to continue their rapid growth.

The EV industry has been innovating to meet consumer demand for vehicles that can go farther on each charge. But this presents an engineering  conundrum: A larger size and capacity battery improves an EV’s range, but the weight of bigger batteries can also negatively impact its performance. As a result, battery makers are working steadily on new space-conscious designs
and battery chemistries that deliver the increased energy density needed for optimized EV performance. Notably, one of the key enablers for a more compact battery is to make the battery connectivity more power efficient with minimal heat loss.

TE Connectivity has worked in the EV industry for more than 20 years with nearly every automaker and tier-one supplier. From that experience, we've seen how important it is to focus on the sophisticated engineering needed to connect battery pack components and connect that power source to the motor, delivering energy most efficiently. The quality and robustness of those electrical connections can be the difference between success and failure.

New battery technologies are driven by the need for increased energy density, charging performance, safety, the battery pack's expected lifespan, and cost optimization.  Additionally, sustainability, recyclability and the circular economy also play an increasingly important role.

EV batteries are typically made up of cells, the building block of an EV's energy storage system. Cells are then often – though not always – arranged into modules. Power flows from cell to cell and then from module to module. Battery module and cell connections constitute the physical layer for battery power transfer, cell-balancing, battery management and protection. To ensure these operations, every individual battery module and cell must feature fail-proof electrical connections. This requires highly integrated contact systems, which must not only be capable of supporting full functionality over the vehicle’s complete lifespan but are also robust enough to prevent vibration and temperature stress adversely affecting the contacts’ mechanical and electric properties. In addition, contacts must also be fully touch-safe in order to eliminate potential high-voltage, high-power hazards and ensure safety during the manufacturing process and future maintenance.

Besides high-voltage power, low-voltage data signals, such as current and temperature from sensors, must be processed and monitored throughout their journey to protect the vehicle through the battery management system (BMS). BMS electronics require highly compact, yet flexible connector systems. Given that the ratio between battery cells and cell controllers vary according to battery design requirements, such as capacity and vehicle energy demands, connector systems must have the flexibility to accommodate multiple connector configuration permutations. Connectors should also have the flexibility to support different types of cables, including flexible flat cable (FFC) and flexible printed circuit (FPC), that can be routed around compact and complex 
battery geometries.

The physical power and data network layers, comprising cables and connectors, will play a pivotal role as the backbone of next-generation safer, greener connected vehicles that consumers want to own, drive or be driven in. This means high-voltage drive systems and low-voltage data connectivity networks must both work ultra-reliably and safely in increasingly integrated centralized (“smart”) architectures.

Today's EVs are expected to handle peak loads for longer periods of time. Higher heat is a byproduct of greater energy transfer – and when electrical components heat up, they undergo an aging process that can change a component's electrical properties over time.

Thermal management is critical during the development phase of all high-voltage connector products. For example, TE engineers have designed battery interconnection systems with minimal heat loss to maximize electricity transfer within the battery pack at very high current rates. TE also can conduct thorough system-level thermal simulations that provide valuable data to help OEMs and their suppliers optimize EV platform designs. These simulations deliver real-world views of a component's temperature limits before any products are built in order to speed up the development process.

For more than a century, advancements in ICE cars have helped improve performance and efficiency. For example, getting gasoline from the fuel tank to the engine is a well-proven process. With EVs, though, the process of moving electricity from the charging infrastructure to the battery, and from the battery to the e-motor is central to improving range and performance.

Most traditional EV electrical platforms are 400-volt systems, but we're seeing an increased prevalence in 800-volt systems, and even 1,000-volt systems are starting to emerge. This is where high-voltage terminals and connectors come into play. These connectors should have configurable, multi-point terminal connections that can be adjusted to the precise current requirements of the application, maximizing energy transfer while minimizing resistance and heat. Additionally, advanced metallic terminal plating technologies offer greater durability over time than standard coatings.

Although EVs are becoming mainstream consumer products, their architectures are still evolving at a breakneck pace. We're amidst a revolution, and automakers worldwide are responding by rewriting their business models from the ground up and investing billions of dollars into EV research and development. It can be very difficult for an engineer or designer to stay up-to-speed on the latest trends and standards, which vary regionally and by the manufacturer.

The challenge at hand: balancing the simplification of EV architectures to allow room for the larger-sized cables and connectors needed for higher voltages and currents while reducing their bulk and weight. In addition, automakers and battery pack manufacturers can benefit from working collaboratively with partners to bring the next generation of EVs to market

TE's engineers and scientists will continue to innovate our electrical connection systems with the demands of advanced battery technologies in mind, helping free OEMs from worrying about connectivity issues so they can focus on other areas of vehicle platform design and production. We hope the bandwidth created by these sorts of partnerships allows OEMs to develop even more EV models and ramp up output, so we can meet the growing global demand for electric mobility that will contribute to a more sustainable future.