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Flexibility is required when designing and placing thermal management components for off-highway EVs that are diverse in form and function. (Modine)

Catering to off-highway EVs’ unique thermal need

Modine exec says EV thermal management systems have evolved significantly from the technology used by ICE vehicles just five years ago.

A rarity only a few years ago, electric vehicles (EVs) are becoming part of the daily lives of constantly increasing numbers of drivers. In the first quarter of 2024 alone, passenger EV sales soared by about 25% compared to the same period in 2023, according to the IEA’s annual Global EV Outlook. While the passenger EV market charges ahead toward widespread adoption, the off-highway vehicle segment lags in electrification.

The burly and rugged workhorses that do the heavy lifting in construction and agriculture have been slower in embracing electrification due to their heavier workloads and duty cycles. In addition to larger batteries, traction motors and countless other components, the electrification of this class of vehicles also requires a steep learning curve, all of which impact stakeholders up and down the value chain. For example, navigating range requirements and harsh environmental conditions remain industry-wide challenges in electrifying off-highway machinery, as does installing the necessary infrastructure of chargers to keep the fleet running.

With over a century of expertise designing diesel and gasoline engine thermal systems, Modine now stands at the forefront of the transition to electricity as an off-highway vehicle fuel. Drawing on its experience in systematic approaches to either removing or adding heat in complex, high-availability, heavy-duty vehicles, Modine has been applying the lessons from its past challenges to build EV thermal management systems that cater to the unique needs of off-highway vehicles.

Right-sizing under design constraints
Vehicles ranging from compact forklifts to imposing industrial cranes have unique space constraints. Because the off-highway market is in the early days of electrification with nascent but growing demand, re-powering an existing vehicle has become an early play for vehicle manufacturers and end users to start the journey. However, re-powering an internal combustion engine (ICE) platform requires a delicate balance of innovation and practicality. This is particularly true when dealing with the challenge of reliably expelling the heat produced by EV components that no longer sit behind radiators centrally or at the front of the chassis.

For example, while developing a comprehensive thermal management system for an electric skid steer loader being electrified by Bosch Rexroth, Modine engineers had to reimagine the layout of the system to fit the confines of the already compact platform. To achieve this, the team designed a distributed system to maximize flexibility in placing thermal management components within the vehicle.

Working on larger vehicles presents a related yet unique set of challenges. Modine collaborated with industrial vehicle industry giant Komatsu to integrate the EVantage L-CON Battery Thermal Management System (BTMS) into a 20-ton electric excavator to optimize performance, extend longevity and reduce downtime. With ample space, the team integrated the BTMS into a single-box unit, underscoring the value of versatility in a thermal management system used in electric off-highway vehicles. From minor adaptations to fully customized designs, the ability to fit any chassis size ensures optimal performance, longevity and efficiency.

Preconditioning key to EV battery success
Off-highway vehicles, diverse in form and function, also require battery systems tailored to address the unique demands of each vehicle’s intended use and operating environment. Each EV lithium-ion battery pack has components highly dependent on cooling technology to mitigate the impact of temperature fluctuations. Unlike traditional ICE vehicles, where engine coolant temperatures can range from 85 to 215°C (185 to 419°F), EV batteries require a much narrower operating window of 20 to 45°C (68 to 113°F). To ensure optimal performance and maximize efficiency and longevity, EV battery preconditioning is a vital aspect of thermal management – and that holds true for everything from passenger cars to commercial vehicles to off-highway machines.

Preconditioning involves heating or cooling a vehicle’s battery to the optimal temperature so that it is ready for maximum operation, a process that is ideally done while the vehicle is connected to a charger. The Komatsu electric excavator, for example, can handle extended shifts and endure a variety of environmental conditions on a large construction site. However, these vehicles do not typically benefit from parking indoors during a project.

When left to charge outdoors overnight, the vehicle batteries risk becoming cold-soaked unless the vehicle is outfitted with a BTMS to keep the battery pack at optimal temperature through the night, avoiding compromised performance when the vehicle starts up in the morning. As such, construction managers must factor a preconditioning strategy into their deployment schedules, vehicle usage patterns and operational plans to ensure the vehicle’s overall success.

In comparison, the Bosch Rexroth skid steer loader might be deployed for more minor, day-to-day construction projects and returned to a depot at the end of the day. The machine can be plugged into a charging station in the depot warehouse, where the overnight temperature remains ideal for the battery. In this case, the skid loader requires a less extensive preconditioning strategy to ensure readiness for deployment the following day.

Adapting to rugged environments
Unlike conventional passenger and commercial vehicles primarily bound to paved roads, electric off-highway machinery must be ready to navigate a diverse range of rugged terrain. Whether on a construction site, farm or mine, these vehicles must endure extreme operating conditions – without compromising performance. In turn, the thermal management systems installed in these electric machines must withstand the harsh and dirty conditions beyond the tarmac.

By leveraging a two-stage system, Modine was able to design the liquid-cooled condenser BTMS to be placed anywhere on the chassis and use the Electronics Cooling Package (ECP) to reject heat to ambient air. The heat exchangers in the ECP are designed to resist clogging caused by poor air quality or high particulate levels, as found in harsh and dirty environments like a construction site. Since the ECP and BTMS are separated, the ECP can be strategically placed on the vehicle to minimize dirt intrusion, and the BTMS can be placed anywhere on the chassis for fit.

To ensure the thermal system design will meet the extreme conditions of off-highway applications, each thermal system is integrated into the corresponding off-highway vehicle platform and then run full-tilt in simulated environments from wind tunnels and climate chambers to the punishment of vibration testing on the rumble track. Rigorous testing must be standard practice. Like many other critical and real-time vehicle systems, thermal management systems must withstand harsh environments and remain operable.

Gina Maria Bonini, VP and general manager of advanced thermal systems for electric vehicles at Modine Manufacturing Company, wrote this article for SAE Media.

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