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Transportation Power

Semi-Trailer Trucks Test Converting Into Plug-In Hybrids (ieee.org) 49

Posted by EditorDavid from the power-plays dept.
Long-time Slashdot reader necro81 writes: There are several companies, such as Tesla, trying to make semi trucks fully electric. The capital cost for such a truck, and the MW-scale infrastructure to recharge it, may be a hard sell for some operators. [IEEE Spectrum notes that's a charging infrastructure "that most freight corridors do not yet reliably provide."] But some companies are instead adding batteries and an electric motor to the semi-trailers that trucks haul behind them.

"The Nivalis Powered Trailer Kit centers on an electric axle [rated at 50 kilowatts-peak]... capable of both propulsion assistance and regenerative braking. It draws on a 60-kilowatt-hour, 400-volt lithium-ion battery pack charged from three sources: the axle itself during braking and deceleration, a full-rooftop array of photovoltaic panels generating up to 3.7 kilowatts-peak, and a 32-amp, three-phase AC grid connection available during parking stops."

This approach is more akin to a plug-in hybrid: the truck may still be diesel-powered, but the electric assist from the trailer allows the truck to run more efficiently. Replacing diesel with kWh can save operators money while also reducing emissions. This incremental approach may be more accessible and less capital-intensive than replacing the truck itself.
From the article: The driver's only window into the system is a small display readable from the cab's side mirror that shows the system status and battery charge level. Nothing about the trailer's handling or licensing requirements changes. The partners project savings of up to 7,000 liters of diesel per trailer per year, which is enough to keep about 19 tonnes of carbon dioxide out of the air...

Trailer Dynamics, an Aachen-based company, has conducted field tests with BMW Logistics, DB Schenker, Duvenbeck, and Volkswagen Konzernlogistik, reporting average fuel savings of around 40% for diesel tractor combinations, substantially higher than the up to 18% reduction implied by the Nivalis projection... Trailer Dynamics prices its system between €145,000 and €195,000 and targets a payback period of no more than five years. Nivalis targets five to six years at current costs.

Semi-Trailer Trucks Test Converting Into Plug-In Hybrids More | Reply

Semi-Trailer Trucks Test Converting Into Plug-In Hybrids

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  • how much for a new electric semi-trailer?

    • The premise of the problem isn't the cost of the semi it's the lack of charging. There's currently only a few MCS chargers available. It's a bit like the debate of an electric car 15 years ago, ... and people are still bitching about charging consumer EVs today.

      • Re: (Score:3, Informative)

        by Sique ( 173459 )
        You don't actually need an MW charger to recharge a semi. Any normal car charger will do. And while most of them max out somewhere around 400 kW, it's still plenty to go from 10-80% in about 40 mins. Just do the math: 400 kW for 40 mins is about 270 kWh, or about the amount you need to go from 10-80% on an 400 kWh battery. That would be sufficient for about 250 miles with a semi.

        German YouTuber Elektrotrucker [youtube.com] does international hauling throughout Europe for more than a year now, and he regularly recharges

        • Indeed, this MCS seems a very niche option, maybe not for USA where they don't seem to have any rules enforced about driver safety and them having a rest. Tobias also has a English version of the channel but he's stopped uploading to it

          • Re: (Score:2)

            by Sique ( 173459 )
            There are regulations [dot.gov] nevertheless. The limit is 8 hrs of consecutive driving, after which a 30 min break is required, and 11 hrs of maximum driving after an 10 hrs break. It would make sense to split the 11 hrs into two 5-6 hrs periods with the 30 min rest in between. With 60 mph, this gives a driving range of 360 miles on a charge. A commercially available Mercedes eActros 600 with 600 kWh of charge would easily be sufficient, requiring a 30-80% charge within 30 mins. Or you go for the 14 hrs total, and s

        • Re: (Score:3)

          by Rei ( 128717 )

          Unfortunately, the math doesn't work that way (even ignoring that a 400kWh battery is very small). Battery packs taper the closer you get to full, they're not a constant power all the way. Unless your battery pack can take 400kW at 80%, you're not charging that quickly.

          Also, while 40 mins is fine in Europe (breaks: 45 minutes every 4,5 hours of driving... though using 70% of a 400kWh pack on a loaded class 8 truck going even at a slow 80kph will only take you 2 1/2h of driving in "average" conditions, s

      • Re: (Score:3)

        by DarkOx ( 621550 )

        Trucking though (long haul) is pretty efficent accross most of the US. You have large loads on engines with tall gearing, and everything runs at pretty stable speeds.

        Most of our interstate highways, with some exceptions in mount regions have a fairly narrow range of again consistent grades.

        A battery-electric boost where efficiencies of the main power train fall down, long grades in the mountains, any kind of stop/go situation due to accidents, road maintenance etc, and the last miles in/near destinations

        • Re: (Score:2)

          by TWX ( 665546 )

          I'd think that tractor tag-axle replacements could be a next logical step, even with no onboard batteries on the tractor and using an umbilical to the trailer's batteries, or else a small set of batteries in the truck, supplemented as needed by a large set of batteries on the trailer.

        • Re: (Score:2)

          by torkus ( 1133985 )

          Your words all make sense but your points don't.

          First: trucking is NOT efficient. Railways are far more efficient for moving bulk goods.

          Consistent grades are still grades and waste a ton of fuel that can't be recaptured - except with an EV and, to a lesser degree, a Hybrid.

          A hybrid will improve efficiency vs ICE in local delivery/traffic but a full EV is still significantly more efficient.

          Putting a hybrid drivetrain into a trailer is ridiculous for the vast majority of situations. There are about 3 semi-tra

      • I live in Oslo, Norway. I'm driving a BMW i3 I bought new 12 years ago. It was a piece of shit the day I bought it. It's the exact same piece of shit now. I've calculate that so far, I'm at about $245 USD per month total cost of ownership including charging and toll booths across these 12 years. I suspect I can drive it for another 6-10 years and by then I expect the TCO to have dropped to about $195 a month before it starts increasing again.

        I can't drive this shit heap too far, 120km on a great day in the

  • In that movie, there's these container haulers that just look like a run-away trailer without the truck, self driving and electrically powered, completely autonomously (and rather inconsiderately of pedestrians) blasting down the roads.

    Well, this development feels like something that could actually lead to that future, a little at a time. Once you electrify the trailer with "assist", it might as well be given the ability to move around "on its own", slowly, around enclosed cargo ports, to facilitate the loa

    • Re: (Score:2)

      by necro81 ( 917438 )

      Once you electrify the trailer with "assist", it might as well be given the ability to move around "on its own", slowly, around enclosed cargo ports, to facilitate the loading and whatnot, and come meet their tow out front, saving the time of the driver and the truck.

      Except that the trailer only has a single electrified axle. It has no steering capability (it doesn't even front wheels to support its weight!), no sensors to be aware of its surroundings, no compute power to make sense of the world and navigate to its destination.

      It's highly likely that we'll end up with "animated death prisms", given enough time, but it's a giant leap from what this article is talking about to that. Any well-resourced engineer could stick a battery and motor onto a trailer. What you

      • Re: (Score:2)

        by T34L ( 10503334 )

        Of course, but my point is that instead of one giant leap, the general direction of electrifying the trailer means you can incrementally inch towards it without trying to make a level 5 death bricks all at once.

        Yeah, it's a single unsteerable axle right now, but if these becomes common, you might as well eventually add steering that'd help with manoeuvres in tight spaces. If that proliferates well, you might as well start tacking on some autonomy to use in enclosed industrial areas. Once you have em rolling

  • Travel trailers too (Score:3)

    by MDMurphy ( 208495 ) on Sunday July 12, 2026 @11:09PM (#66235358)
    There are a few electric travel trailers out there now. They are fully electric, like these, but I guess when you combine with the hauling vehicle you could call the whole system a hybrid. Besides the usual regenerative braking, you could apply a little resistance on long flat stretches of road to top off the battery for either an upcoming hill, or to run a refrigeration unit. With route planning, the system could know if you have a big hill coming up and need to top off, or if you'll be dropping the trailer before then.

  • Scalable? (Score:2, Insightful)

    by Anonymous Coward

    My first thought is it doesn't seem particularly scalable -- there are so many more trailers than there are tractors...

    • This. And it pretty much flies in the face of the intermodal transportation system.

      It's a nice idea, but who equips their trailer with this to save money for the stranger hauling it around?

      • > It's a nice idea, but who equips their trailer with this to save money for the stranger hauling it around?

        Fleet operators, where they don't have strangers hauling around their trailers; e.g. USPS, Amazon, FedEx, UPS.

        =Smidge=

  • For the best hybrids, the major advantage is not the regenerative braking. While that helps save some energy, it is relatively minor.

    Instead the main advantage is that you can design the internal combustion engine (ICE) to run at a consistent RPM. You do not need to run the ICE at different speeds to get 30 mph, 45 mph and 60 mph. Instead you have one that just runs at a set RPM. Then you use the hybrid battery to supply all the power at low speeds and a boost at the max speeds.

    The more efficient ICE c

    • It's more than just a set RPM. It is also a set power level. An ICE engine is typically the most efficient at a set RPM and 70-80% of maximum power for that RPM.

      Then size the engine for roughly highway speed on level terrain. Maybe give it the ability to go higher in RPM - less efficient, but able to handle going up a big hill/mountain if necessary. But ideally the battery would handle that, then charge up on the way down.

    • The major advantage is being able to use an engine that's worthless for acceleration, e.g. Atkinson cycle. All ICEs are most efficient at a specific point on the torque/RPM chart so that's not the differentiator.

      Regen braking is the biggest benefit in the city. It's essentially irrelevant everywhere else, but whether it matters most or not depends on where you're driving.

  • This seems dubious... (Score:5, Insightful)

    by dgatwood ( 11270 ) on Monday July 13, 2026 @02:36AM (#66235542) Homepage Journal

    This seems dubious at multiple levels.

    Solar panels: The roof of a trailer is about 450 square feet. In the northeastern U.S., you would average only 3.5 hours of full sun, so you'd get only a little over 13 kW per day.

    Tesla semis are pretty efficient, and they use about 1.7 kWh per mile. So in an entire day, covering the entire roof of a trailer with solar panels would add a whopping 7 miles of range, or 15 minutes of extra driving — the equivalent of plugging into a Tesla Megacharger for maybe 30 seconds or so.

    Let's optimistically assume that the vehicle can carry 48,000 pounds. If those panels occupy the full roof area, then at about 3 pounds of weight per square foot, those solar panels would weigh 1500 pounds, or about 3% of your cargo, all to reduce your fuel usage by as little as 1% if you're doing long haul at 65 MPH. And that weight number may be wildly optimistic. Trailers like that aren't designed to have weight on the roof, and would require additional structure to hold that extra weight. The real losses could be significantly higher. Unless you're driving less than a couple of hundred miles in a day, the solar panels won't break even. And if you're driving less than a couple of hundred miles per day, there's no reason you can't go electric.

    Battery and motor on the trailer: I would expect most trucks to be used primarily for either short-haul or long-haul purposes, not both. If you're doing long-haul, you'd probably be better off with an actual hybrid tractor so that you get the benefit no matter whose trailer you're hauling. If you're doing short-haul, there's likely no reason not to go full electric.

    I just don't get it.

    • Solar isn't for extending range, it's for self charging while idle. It's never been a viable way to extend range and only ever a suitable addition for any device that may spend a lot of time stationary.

      And example of such a thing would be ... a trailer. These things can spend a significant portion of their life parked.

      By the way I just checked, apparently most of the world is not "Northesatern USA" despite how much Washington State would have you believe otherwise. Using the worst case on a national level t

      • Re: (Score:2)

        by DRJlaw ( 946416 )

        Most of the world is not Northern Canada, which must be where they got that number from. Maine averages 4.55 peak sun hours per day [thegreenwatt.com], and is the northereasternmost state in the continental United States. Even Washington state is at 3.95 [thegreenwatt.com].

      • I just checked, Washington State and Seattle are both not in the Northeastern USA and are unaware of any campaign to convince the world otherwise.

        • I just checked, Washington State and Seattle are both not in the Northeastern USA and are unaware of any campaign to convince the world otherwise.

          Well so what I said was true then, despite my usual issue of getting east and west confused. X-D

    • Re: (Score:2)

      by DRJlaw ( 946416 )

      Solar panels: The roof of a trailer is about 450 square feet. In the northeastern U.S., you would average only 3.5 hours of full sun, so you'd get only a little over 13 kW per day.

      So the solar generation function of a panel is no sun, no power, partial sun, no power, peak sun hours, full power.

      Well, I guess that you're the expert.

      So in an entire day, covering the entire roof of a trailer with solar panels would add a whopping 7 miles of range

      Maybe that's enough to get you over a time zone or so so that you

  • I like the concept! But the practicality is questionable, especially at that price.

    The solar charging peak seems much lower than I'd expect. My thinking is that it should be closer to 8k peak. I wonder why their estimates are so low. But, even at 8kW, and a generous 4 hours of good production it's not nearly enough.

    But, the price is a big factor. Can these trailers hope to produce enough savings to justify a 5X increase in cost per trailer? I highly doubt it.

    People grossly underestimate the energy density o

    • I guess while they save 7000 liters of diesel per year, the extra cost is more than 70 000 liters worth of money. And if the tractor and trailer are not owned by the same company, some political tricks are needed, like tax cuts.

  • I kinda wonder if it's worth it though. In the configuration described in TFS, at full charge that battery is only good for about 80 horsepower. And count on less than an equivalent reduction in fuel consumption because of things like the added weight of the battery and the motor.

    I'm all for doing these experiments. But one of the systems described in TFA costs between 145k and 195k Euros per trailer. Multiply that by even a few transport fleets, and I have to ask if that money could be better spent on rewo

  • Have each car help. Could even make them self driving in rail yards to assemble themselves onto trains.

    • What if short distance trains didn't even need batteries, but instead simply got their power from the rails or from overhead wires.

      • I live in the US, and there are short distance trains like that. But mostly we don't have short distance trains, and electrifying our very long routes wouldn't make economic sense.

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