A major factor holding back the adoption of electric vehicles has been ‘range anxiety’ – the worry that you won’t reach your destination, or will at least need a lengthy break for charging. This is important for cars, but absolutely critical for heavy-duty vehicles. For trucks and buses, utilisation is key: every minute off the road is revenue lost. And truck and bus operators with detailed knowledge of routes and schedules know how much they are losing.

One distinct feature of truck and bus driving is mandatory rest breaks: in simple terms, truck drivers in Europe must stop for at least 45 minutes after every 4.5 hours of driving. The timed stop precludes any ‘work’ activity, giving drivers the chance to plug in their vehicle and then go for a rest or a meal. In principle the calculations for charging rates and times are simple: the capacity of the battery (in kilowatt-hours, kWh) divided by the charging rate (in kilowatts, kW) gives the charging time – so a 100 kWh battery charged at 200 kW should take 100/200 or half an hour to charge. But, in practice, charging slows down considerably when the battery is at a low or high state of charge (below 20% or over 80% SoC) – all the more reason to speed up that middle 20–80%.

In theory, a megawatt charger could supply 750 kWh of energy in that 45 minutes – more than the total capacity of a Mercedes-Benz eActros 600’s battery pack, and certainly more energy than a 40-tonne truck would use in the next 4.5 hours.

Just how much power does a megawatt (1 MW, or one million Watts) represent? By comparison one horsepower (hp) equals just 746 Watts, so 1 MW is around 1,340 hp. That’s roughly twice the power of an F1 car, or the average power demand of several hundred typical households, going through a cable and a connector that need to be readily handled many times a day.

How will new truck chargers compare with the old ones? 
Up to now, most heavy-duty electric vehicles have used the Combined Charging System (CCS) charging connector, a multi-purpose plug and socket capable of supplying DC charge at a typical maximum power of 400 kW – fast enough to theoretically charge any electric car in 20 minutes or less. But automotive trade body CharIN (the Charging Interface Initiative eV) has been developing a more substantial standard for heavy-duty vehicles, which is just coming onto the market. MCS is a substantial advance on CCS, with a potential maximum charging rate of 3.75 MW – the product of a maximum voltage of 1,250 volts and a maximum current of 3,000 amps.

Importantly, both charging system suppliers and vehicle manufacturers are committed to the standard. ABB undertook testing with Scania in 2023, then demonstrated a 700 kW MCS charge with an MAN articulated truck in March 2024, while Siemens showed a 1 MW charge with a Mercedes-Benz eActros 600 soon after. Finnish firm Kempower recently started pilot deliveries of its first MCS charging units and ‘dispensers’ – the visible part of the unit that the driver interacts with. ‘Unfortunately, we can’t reveal the customers,’ says Antti Vuola, Kempower’s Director for Market Segments, ‘but I can tell you that the first deliveries are for trucks – for logistics purposes.’

‘Of course, you can charge trucks without MCS, but in many cases where you have long-haul trucks, you need MCS to recharge during that 45-minute driver break. That’s where you get the smallest downtime.’

MAN’s eTGX being demonstrated with MCS charging 
Photo: MAN

Charger challenges 
Thermal management is probably the biggest technical challenge with megawatt charging. This applies at every level, down to individual components – for instance, Omron offers relays with extra-low switching resistance to reduce heat buildup. The charging cable and connector are at the sharp end, and ergonomics is an issue. If the cable is too large, it becomes unwieldy (both heavy and inflexible) and if the connector gets hot it becomes a hazard. Liquid cooling is the solution: a specialised coolant is pumped through the cable assembly and connector body – even within the connector pins themselves – and returns to a heat exchanger built into the charger. This has been claimed to cut the weight of the cable by 40%.

Vuola explains that there are three levels in MCS: level 1 goes to 350 kW, level 2 to 1.2 MW and level 3 to 3.7 MW. Levels 2 and 3 use liquid-cooled cable, but in level 1 you have an air-cooled cable.

He adds: ‘Today we are talking about level 2, but there is still level 3. And I think when we get to 3.7 MW, we have a lot of new applications available, like open pit off-highway machinery, port equipment, heavy materials handling, construction – all these will require MCS.’

CharIN is developing the ‘Ruggedised MCS’ standard, driven by the needs of massive off-road dump trucks and other equipment. Ruggedised MCS goes up to 1,500 volts and 4,000 amps, for a maximum charge rate of 6 MW. Unsurprisingly, the standard states that operation ‘is not allowed in public spaces and requires trained operators wearing gloves’ – indeed, it will also accommodate automated connection systems.

Perhaps the biggest challenge for megawatt charging is the impact on local electrical infrastructure; although most units are designed to run off the 400 volt, three-phase AC supply standard in Europe, with a single charger potentially dispensing as much electricity as a small town, the electrical grid could become overwhelmed. Vuola points out that a highway fast charging station ‘could easily be 10 MW – just having ten 1 MW chargers… quite a lot of power.’

How can you manage all the power? 
One solution is the ‘battery-buffered’ charger, which combines a conventional charger with a stationary battery pack. This is charged while the charger is unused (ideally while demand is low generally) and assists the charger when it needs to feed an electric vehicle. This way the charger can be supplied from a ‘weak’ source such as a standard 400 volt supply, or a local solar array – and offer battery-to-grid support. ‘The bigger we go with power, the more we will see energy storage,’ says Vuola, ‘balancing the grid, cutting the peaks and ensuring there is enough power for peak times.’ Manufacturers are talking about ‘microgrids’ combining mains, battery and renewable sources, to smooth demand and add resilience.

The charging hardware on its own is not enough, though: chargers need to be integrated into the local supply grid, and customers want energy from the optimal source. This is why hardware firms have linked with systems integrators and software specialists, like Schneider Electric’s partnership with The Mobility House, whose investors include Alliance Ventures (Renault-Nissan-Mitsubishi) and Mercedes-Benz. And the MCS standard includes an upgraded data channel, using protocols similar to Ethernet and hardware specifications that can withstand harsh electromagnetic interference.

Clearly there will be standards which replace MCS at some point – and developments in wireless (inductive) charging, automated connectors and swappable battery packs – but MCS has a way to go yet. Indeed, CharIN states: ‘In the close future… MCS shall also be used to charge other heavy-duty vehicles like e-ferries, ships, and planes.’

• Further reading: ‘Speeding ahead: truck sector gears up for net zero’. The heavy road freight sector in the UK and Europe is gearing up to switch from diesel to predominantly battery electric trucks, according to Transport & Environment, along with hydrogen fuel cells and e-fuels, to accelerate decarbonisation on the road to net zero.
• Growing adoption of electric vehicles is boosting demand for the critical minerals needed to build new batteries. As these batteries reach end-of-life it is crucial that the materials they contain are managed and recycled appropriately. In parallel, there is an emerging market for second-life batteries with innovative applications.