Electric heavy duty vehicles (HDVs) are currently the sizzling segment in terms of powertrain and thermal management systems technology.
Following the electrification trend of passenger cars and mobility as a service (MaaS) vehicles, HDVs are the subject of furious development by OEMs, as they pursue increased efficiency and range whilst reducing production costs. So, what are the latest developments and obstacles in electric HDV technology?
The recent launches of new vehicles and prototypes are a sign of what is to come. In March, Skoda Electric and Germany firm Proton Power Systems announced a partnership to develop, sell and service fuel-cell electric buses using the latter’s ‘HyRange’ systems. According to electrive.com, the prototype fuel-cell electric buses built by Skoda Electric would be available to European bus operators by the first quarter of 2020.
Skoda Electric is not part of the Volkswagen Group and focuses on constructing e-motors for the heavy duty segment, whilst Proton Power Systems may now have a link with VW AG through its joint venture with German start-up e.Go Mobile. It was recently announced that the latter firm is the first independent company that will make use of the VW Group’s forthcoming MEB platform for electric vehicles.
More developments
In 2018, Polish-Spanish company Solaris delivered 107 electric buses to clients across Europe, which it claimed represented a market share of 17 percent of all electric bus sales during the same period. Solaris is runner-up in market share to Chinese giant BYD/ADL, who took 25 percent of sales. Solaris also faces competition from the Netherlands’ VDL, with 13 percent, and China’s Yutong, with nine percent.
On a similar note, Lion Electric from Canada, known for its electric school buses, has started the expansion of its commercial electric vehicle catalogue by announcing the release of its first electric truck (above). In the US, the vehicle conforms to the Class 8 classification, which corresponds to local trucks over 15 tons. The Lion8 truck offers a battery capacity of up to 480kWh, giving a claimed range of up to 400km, using NMC cells from LG Chem, claims Lion Electric. Charging times vary from 2.5 to 16 hours, depending on the charger type.
The vehicle is scheduled to go on sale in autumn 2019. It was disclosed that the vehicle’s first client is Société des Alcools du Québec (SAQ). Lion Electric envisions that the truck will operate predominantly in cities, but claim that customers who order the most substantial battery package could potentially use Lion8 trucks on inter-city routes, albeit dependent on Canada’s infamous winter weather.
Tech Challenges
Given that the electric HDV market is growing, it’s no surprise to learn that the biggest OEMs are working hard to overcome the technological obstacles that hamper this segment. Heavy duty vehicles require high-power charging stations. This means higher impact on grid power quality, more high-energy cells to increase range and reduce the weight of the battery pack, and higher cooling power and more auxiliary units, which means increased complexity.
Power infrastructure
Vehicle-to-Grid (V2G) technologies, which enable bidirectional power between EVs and grid, can mitigate the limitation of the installed grid power. Industry leaders such as Siemens, ABB and Schneider Electric have been developing solutions in this field. Considering the power demand, protection, safety and remote monitoring requirements of the charging stations, the smart grid concept appears to be the future trend that really can speed up the electric HDV market.
Weather dependent
Current cell technology limits the battery discharge and charging rates in low temperatures. Practical consequences of current battery technologies in real-life conditions are the limitation of the regenerative energy, power de-rating and range. For example, in cold start conditions of -10 degrees Celsius, the HDV may not be able to climb a hill with 20 percent gradient until the heater heats the battery to an optimal temperature.
In addition, vehicle range is limited at low temperatures since the regenerative energy is restricted due to the limitation of the battery charge current.
Therefore, new cell technologies are expected to improve battery performance in cold and hot weather conditions. This will reduce the power requirement of the thermal system that keeps the battery pack within permissible temperature limits.
An alternative way could be the development of more efficient thermal systems for the batteries. “Solid-state batteries can speed up the commercialization of HD vehicles,” says Mustafa Karamuk, Senior R&D Engineer at Ford Otosan. One of the benefits of this concept is that it relies on lithium-metal anodes that store two to three times more energy, compared with traditional lithium-ion batteries.
Playing it safe
At cell level, solid-state electrolyte is a promising solution to the electrolyte safety problem, which possesses intrinsic thermal characteristics and can form a natural barrier for ISC prevention. The separator is the key element in lithium-ion batteries to prevent direct contact of the anode and cathode, but provides viable corridors for lithium-ion transport.
The development of electric HDV power is also a matter of economy. Current technological growth has taken the direction of higher efficiency and reduced sizes for e-powertrain components. However, at the same time, these technologies bring higher component costs and the requirement of a long-term commitment from Tier 1 suppliers. OEMs are facing the challenge of uncertainty in the market.
Thermal Design
HDVs require new thermal design concepts, as they are needed to manage complexity and optimize system efficiency. The big challenge is to find a cost-effective off-the-shelf power solution that suits market requirements. However, such suppliers are limited, although Ford Otosan is developing an electric truck prototype with cost, time, efficiency and range in mind (previewed with the F-Vision concept, above).
In Conclusion
Bigger battery capacities, more effective thermal management systems, and a more robust grid are still significant obstacles that must be overcome if the advancement of HDVs is to match that of the passenger car segment. However, as emissions regulations in Europe edge toward implementation and demand begins to increase for more sustainable transportation solutions beyond the personal car, this are of the industry is surely set to grow. Time will tell how the issues will be solved, but the rise of the electric HDV is surely set to continue.
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