56 May/June 2025 | E-Mobility Engineering Nick Flaherty connects with the latest developments in megawatt charging systems for heavy-duty electric vehicles Charging ahead In 2018, the Charging Interface Initiative (CharIN) formed the Megawatt Charging System (MCS) Task Force to develop a robust, scalable and interoperable system for fast charging of electric heavy-duty vehicles. The goal was to meet the growing demand for fast, efficient charging of high-capacity batteries in commercial heavy-duty vehicles. To carry heavy payloads over long distances, large trucks, ships and construction equipment need larger battery packs, which means that they need fast charging and high power levels. Fast charging with megawatts of power can reduce the battery pack requirement from 1000 to 450 kWh, saving both weight and cost. However, there are a number of engineering challenges with MCSs, ranging from the heat generated in the charger and the charging cables to the distribution of the large amounts of current at high voltages required to support simultaneous charging of many trucks. To address these problems, researchers have been working on new architectures for charging stations and pilot systems are now starting to roll out. At the same time, the standards and interoperability tests are maturing, and the technical information for the SAE J3271 MCS was released in March 2025. This is intended for any large EV that “rolls, flies or floats,” including mining, marine, aviation, rail, agriculture and construction applications, says Ted Bohn, principal electrical engineer at the Argonne National Laboratory and chair of the SAE J3271 committee. Larger-capacity batteries designed to support long-range and heavy load capability up to class 8 vehicles require higher charging power to keep the recharge time manageable. Existing systems based on the SAE J1772 Combined Charging System (CCS) standard can deliver up to 1000 V/ 500 A today for 500 kW charging, while SAE J3400 defines the North American Charging Standard (NACS) systems that can deliver up to 1000 V/900 A or 900 kW. The DC charging Technical Information Report (TIR) for SAE J3271 for MCSs of up to 1500 V/3000 A or 4.5 MW, covers the charging equipment and control elements from the point of utility interconnection to the vehicle battery terminals. It is estimated that up to 18 electric vehicle supply equipment (EVSE) manufacturers are developing SAE J3271 MCS-compliant EVSEs, largely as higher-power versions of their existing CCS products, says Bohn. Because the The MCS connector in the NEFTON project (Image courtesy of MAN)
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