Environmental Testing for Electric Vehicle Batteries

Vehicle electrification is here to stay. The latest reports suggest electric vehicles (EV) will reach 29.5% of all vehicle sales by 2030, a significant jump from 3.4% in 2021. That estimate accounts for roughly 4.7 million EVs on the road per year by the end of the decade. Some economists suggest the consolidation to EV mass adoption had already begun by late 2021, citing factors including new technology, emissions regulations, environmental considerations, cost, and a rapidly changing market as key elements toward jettisoning petroleum vehicles. As demand increases, manufacturers are eyeing advancements in battery technology to make EVs more accessible, economical, and longer-lasting. 

What are EV Batteries?

Unlike internal combustion engines, EVs rely on an electric traction motor powered by an onboard electric battery pack. The traction battery pack which drives the motor must be rechargeable, and the race continues to develop lighter, longer-lasting, and more efficiently charged battery packs. Part of the initiative to advance EV adoption is eliminating range anxiety, which is the fear of being stranded between charges. Some battery manufacturers today are introducing paradigm shifts in battery charging capacities, with one company demonstrating a proof of concept battery that powered an EV 752 miles without recharging. While this type of extended range relies on dual-energy chemistry, there largely remain four types of battery technology used in EVs today. 

Lithium-Ion 

By far the most widely utilized battery technology in EVs today are lithium-ion batteries. These batteries are also widely used in consumer electronics and are prized for their high energy per unit mass and high energy to weight ratio. Lithium-ion batteries have demonstrated excellent energy efficiency, strong high-temperature performance, and relatively low self-discharge. Emerging manufacturers are combining low-cost and durable lithium-ion technology with high energy density lithium-ion chemistry to produce a dramatically extended EV range. However, the battery and performance life of lithium-ion batteries are subject to high-temperature degradation, combined with high production cost, difficult recycling capacity, and currently inadequate recharging infrastructure. 

Nickel-Metal Hydride 

Nickel-metal hydride (Ni-MH) batteries represented the largest percentage of batteries in EVs and hybrid-electric vehicles (HEV) in the early 2000s. Because of their wide use, these batteries paved the way for lithium-ion technologies used today. These batteries are considered generally safe, while offering reasonable specific energy and power capabilities. With the advantages of high energy density and power, reliable operating thermal properties, and cost-effective recyclable material sourcing, Ni-MH batteries demonstrated promising capabilities. However, recent advancements in battery technology have yielded lower weight and cost alternatives, rendering Ni-MH batteries essentially obsolete in EV propulsion. 

Lead-Acid

Unlike lithium-ion and Ni-MH batteries, lead-acid batteries are commonly used to supplement other energy sources in EVs today. Valued for their low cost to power ratio, safety, and reliability, lead-acid batteries continue to hold strong advantages for specific use applications. More advanced lead acid batteries are currently in development for use in commercial electric vehicles for ancillary loads. Despite their advantages, these batteries demonstrate poor cold temperature performance coupled with a limited lifespan, rendering them largely prohibited for single-source EV battery power supply. 

Ultracapacitors

Ultracapacitors have become a viable option for automotive OEMs and Tier 1 suppliers over the last few years based on their ancillary power supply for common road encounters including hill climb acceleration and regenerative braking. The unique technology enables energy storage in a polarized liquid between an electrode and electrolyte. As the liquid surface area increases, so does the energy storage capacity. Another recent advancement is the ultracapacitor-powered active roll system which electrically controls the stiffness of roll bars, allowing efficient cornering by placing an electric motor on the vehicle axles. Ultracapacitors also offer a wide temperature performance range, generating quality performance even in cold temperatures where common batteries fail to perform. 

WHAT IS EV BATTERY TESTING?

As advancements in EV battery technology pace EV adoption, understanding the safety, reliability, and effectiveness of EV batteries is critical to their sustained implementation. Manufacturers continue to develop enhanced battery technologies to reduce cost, increase range, and shorten charging capacity timelines to appease customer demand. Environmental test chambers provide the means to understand and implement these enhancements while bolstering consumer confidence. EV batteries are exposed to extreme environmental conditions like heat, cold, vibration, and corrosion in battery test chambers to assess real-world conditions and validation. Testing to specific industry and OEM standards demonstrates EV battery safety and reliability, while also revealing potential design faults in the early developmental process. Several common international and OEM EV battery testing standards include:

ISO 16750

This international standard applies to electrical vehicle systems and components by describing potential environmental stresses and test requirements recommended for the specific mounting location in or on the vehicle.

ISO 12405

Similarly, this international standard specifies test procedures for lithium-ion traction battery packs and systems for use in electrically propelled road vehicles. These procedures specifically provide determination for performance, reliability, and abuse of lithium-ion battery packs.

LV 124

This quality and reliability standard was jointly developed by German automotive manufacturers in 2013 to test electronic components in 12V electrical systems. It is widely used by European automotive manufacturers to test and validate lithium-ion batteries and powered components.

Saftety Considerations for Battery Testing

Safely testing EV batteries is critically important as advancements in technology produce higher energy densities in lithium-ion batteries. As batteries are exposed to extreme environmental conditions and stresses, potential events include overloads, malfunctions, and thermal runaways. In some cases, events in a single cell can spread throughout other cells and destroy the entire battery. 

To better address and standardize the potential risks associated with automotive battery events, the European Council for Automotive R&D (EUCAR) has significantly invested in hazard classification resulting in specific safety levels associated with key events. These range from Hazard Level 0 resulting in no effect or functional limitation, to Hazard Level 7 resulting in complete decomposition of the battery cell. Battery test chamber manufacturers comply with EUCAR hazard safety standards by advising specific safety equipment relevant to customer-specific testing. These features vary from customer to customer and are largely dependent on the EV battery composition, quantity, energy storage capacity, and proximity of the equipment to adjacent infrastructure. 

Russells Technical Products is a trusted battery test chamber manufacturer for customers in automotive, aerospace, defense, renewable energy, and more. Our battery test chambers conform to a variety of industry standards capable of testing conditions including high and low temperature, humidity, altitude, and vibration. Contact us today to learn more about our battery test chamber capabilities in both reach-in, walk-in, and drive-in configurations.