The commercial trucking industry is undergoing significant changes as fleets, manufacturers, and local and state governments are preparing and making strides towards zero-emissions.
Perhaps one of the most important new technologies is Megawatt charging, which is based around a new charging standard called the Megawatt Charging System (MCS) that allows for charging up to 3.75 megawatts. To compare, current chargers only offer up to 1.2 megawatts.
In other words, battery-electric Class 8 rigs, such as the upcoming Tesla Semi, require a lot more power to fully charge their batteries.
Mark Van Wingerden, Eaton's eMobility product strategy manager, gave an informative keynote speech at ACT 2025 where he explained that while Megawatt charging is necessary, it's not always the right solution for every commercial BEV.
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Jay Traugott
Megawatt charging. It's the fastest way to charge an electric truck. But what are the fastest way isn't the best way. This idea comes from a keynote at Expo 2025 where Marc Van Winkle, Dan Eaton's e-mobility product strategy manager, explain why megawatt charging only makes sense for certain fleets. Not every electric truck on the road. Before we go deeper.
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Jay Traugott
Sign up for our newsletter using the link below for clear updates on fleet electrification and charging trends. Just like this. First, what is megawatt charging? Megawatt charging revolves around the megawatt charging system. Or mix, a new standard for charging that allows trucks to charge at power levels up to 3.75MW. However, the chargers actually being deployed today using MCs typically deliver around 1.2MW.
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Jay Traugott
These chargers can take a class eight electric truck from a 20 to an 80% charge in less than 30 minutes before megawatt charging. The fastest truck chargers topped out at around 500 to 600kW. Roughly half the power of these new 1.2MW systems. So how much power is that, really? Let's put it in perspective. During a big NFL game, a stadium can draw around ten megawatts of electricity.
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Jay Traugott
So charging eight trucks at 1.2MW each is like operating an entire football stadium. Since megawatt charging can deliver huge amounts of power quickly, why don't we just charge every truck at this speed? According to Mark, there are four major reasons why fleets should think twice about trying to charge faster.
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Mark Van Wingerden
So the first one is the battery itself and the cell temperature. Cells are a lot like people. They like to be at relatively close to room temperature. If they get too hot, they get unhappy. They stop performing well.
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Jay Traugott
A battery charger is fastest when it's cool and nearly empty, but as it fills up, charging naturally slows down.
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Mark Van Wingerden
Looking at the room, were quite full at the moment. If you imagine that this whole room is a battery, when there was nobody here, it might have been fairly easy to come in and find a seat, but now that the seats are filled, everyone's standing around the outside waiting. Because, you know, they can't find a place to go.
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Mark Van Wingerden
The battery is exactly the same way. So your charging speed as you get to that upper limit of your battery is going to slow down.
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Jay Traugott
And because of the slow down at the top end, fleets sometimes end up using larger batteries than they actually need for their routes just to make fast charging practical. Second, battery size. In chemistry. To charge super fast, a battery either has to be larger or use a chemistry designed for high C rates. A battery C rate dictates how fast it can charge or discharge.
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Jay Traugott
This is shown in a chart mark presented as a C read goes up. So does P charging power, but only if the battery is big enough. In other words, faster charging can mean bigger, heavier, and more expensive batteries that cut into your cargo capacity and budget.
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Mark Van Wingerden
For optimizing more towards this 1 to 1.2 megawatt. We can do that with a much more reasonable sized battery in the 300 to 600 kilowatt hour range.
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Jay Traugott
Third, thermal bottlenecks.
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Mark Van Wingerden
We also need to look at the thermal bottlenecks in the system. So every point of internal resistance along the long chain of connections from the charging port into the batteries is going to add inefficiency and create heat.
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Jay Traugott
Megawatt level chargers push so much current that even small amounts of resistance generate a lot of heat. That means every wire connector and onboard component must be carefully sized to handle the load, monitored in real time by software, and cooled effectively to prevent damage.
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Mark Van Wingerden
But we don't want to be over sizing the components if we don't need the charging performance.
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Jay Traugott
In other words, you shouldn't overbuild for maximum charging speed if you don't actually need it because it adds unnecessary cost and complexity. Fourth fault protection.
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Mark Van Wingerden
We're talking about big batteries, big stored energy, and high potential for for fault currents.
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Jay Traugott
When you move this much energy, a fault like a short circuit can unleash a surge of electricity that can hit 20,000 to 70,000 amps in an instant. That's enough to melt metal in a flash. Therefore, megawatt charging systems need robust safety systems like industrial grade breakers that can reset heavy duty fuzes that limit dangerous spikes and multiple layers of protection to keep drivers and equipment safe.
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Jay Traugott
So with these four limits in mind how batteries behave, how they're built, how much heat they create and how they're kept safe. Let's look at a frameworks presentation that brings it all together. The one megawatt charger in orange is fastest, but only for a moment. It hits a wall because of thermal limits in the battery's state of charge.
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Jay Traugott
The 500 kilowatt charger in green is a middle ground, but it still steps down as the charge increases. The 150 kilowatt charger in blue is the slowest, but it's consistent and simple. It operates below the continuous rating of all of the components, reducing stress and eliminating the need for extra cooling. The key takeaway is that doubling your peak power doesn't come close to cutting your charge time in half.
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Jay Traugott
You get diminishing returns fast. This chart visualizes why faster isn't a simple solution that leads to the real question what kind of charging does a fleet actually need? To explain this, Mark gave examples of three common fleet types using data from Nafi run on less. In each example, you'll see a clock face graphic that illustrates the ideal operation and charging schedule for each scenario.
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Mark Van Wingerden
Looking at a single shift local delivery, they're only using about 250 kilowatt hours during that shift, and they sit for over 15 hours. Theoretically, you could handle this with level two AC charging.
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Jay Traugott
Many local delivery trucks spend most of their day parked overnight. That means they can easily charge at lower speeds. They simply don't need megawatt charging because they have plenty of time to recharge between shifts. Trying to push 1.2MW into these trucks would just cost more money for no real benefit.
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Mark Van Wingerden
The next is regional delivery. Now we're talking about more time on the road. Two shifts, 15 hours. We're using 1500 kilowatt hours. It's mostly city driving, not a lot of highway. And our dwell time is down to seven hours.
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Jay Traugott
Regional trucks run longer hours and use more energy, often 1500 kilowatts a day, but they still get to windows of around 3 to 4 hours to recharge at a depot or hub. For these fleets, 500 to 600 kilowatt chargers hit the sweet spot fast enough to top off in a few hours, but without the cost or complexity of full megawatt systems.
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Mark Van Wingerden
Now we look at the what everyone considers to be the hardest situation to electrify long haul sleepers. Where we're moving down the road, we don't know exactly where we're stopping. We're consuming over 2000 kilowatt hours in that single day of driving.
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Jay Traugott
Long haul electric trucks burn through over 2000 kilowatt hours in a single day, but federal regulations mean drivers must stop every eight hours for a 30 minute break to keep these rigs rolling. You need to dump hundreds of miles of range back into the battery during that short break. That means charging at one megawatt or more, or the truck simply can't cover enough ground to stay competitive with diesel.
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Mark Van Wingerden
So we are trying to pack in all of this energy into as few charging stops as possible, and we're trying to add 2 to 300 miles of range back in that time period. This is where we need 1 to 1.2 megawatt charging.
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Jay Traugott
So the next time you hear about megawatt charging, remember this. It's better to match the charging speed to the job rather than maxing it out for every truck. To learn more about electric truck charging and battery maintenance, watch this playlist on the screen right now.
