As more fleets of medium- and heavy-duty vehicles go electric, there’s a growing awareness that building the necessary charging infrastructure will be a complex proposition, requiring specialized expertise and considerable capital.
Fleet vehicle depots will need to incorporate not only charging stations, but energy management systems, and possibly energy storage and on-site generation. These sites will also require massive amounts of power capacity, and that means close coordination with local electrical utilities.
Optimal sites for EV fast-charging corridors requires things like on-site storage, on-site electricity generation, and a really large interconnection to the grid.
Join this webinar with TeraWatt Infrastructure CEO Neha Palmer, where we will discuss how optimal sites for EV fast-charging corridors will require things like on-site storage, on-site electricity generation, and a really large interconnection to the grid.
This webinar hosted by Charged on Feb 9, 2023 01:00 PM EST will feature a presentation and live Q&A.
Unlike traditional current collectors made of copper foils, the SMCC is made of a micropatterned shape-memory micron-sized film with copper deposition. According to the researchers, it displays ideal conductivity at normal temperatures and becomes insulative at overheating temperatures; a battery containing an SMCC normally runs at temperatures lower than 90° C (194° F), but if it overheats, it quickly performs self-shutdown before the occurrence of battery combustion and explosion.
The research was conducted by covering a thermally responsive shape-memory polymer with a conductive copper spray, resulting in a material that transmits electrons most of the time but switches to being an insulator when excessively heated.
When the battery reached a temperature of about 197˚ F, a microscopic 3D pattern programmed into the polymer appeared, breaking apart the copper layer and stopping the flow of electrons. This permanently shut down the cell and prevented a potential fire.
The researchers say that at normal operating temperatures, the battery with the new SMCC maintains high conductivity, low resistivity and a cycling life span similar to that of a traditional battery cell. With this technology, they say, batteries can be safer with no sacrifice in performance.
EV fleet-as-a-service (FaaS) provider Zeem Solutions has announced that client Kuehne+Nagel is successfully operating electric box trucks for air cargo freight forwarding at Los Angeles International Airport.
Under Zeem’s FaaS model, Kuehne+Nagel fleet drivers arrive at Zeem’s Los Angeles EV depot, park their personal cars, and drive away with a fully charged medium- or heavy-duty EV to run their routes, taking advantage of driver amenities, regular maintenance and secure overnight vehicle parking, which are all included in a flat monthly fee.
Kuehne+Nagel uses the electric trucks to make pickups and deliveries serving regional warehouses and distribution centers within a 60-to-90-mile radius of LAX. Drivers learn to maximize mileage with training from the Zeem Solutions team.
Zeem Solutions offers a selection of Class 2-8 vehicles. Kuehne+Nagel chose the Sea Electric Hino 195 Class 5 box truck, the Lightning 6500 XD Class 6 box truck and the Volvo VNR Electric Class 8 semi.
Zeem says Kuehne+Nagel is one of many fleets that are operating EVs from Zeem’s LAX depot, which offers nearly 100 EVs and is in the process of installing 77 fast charging ports and 53 Level 2 chargers. During the coming year, Zeem plans to bring its EV FaaS offering to new regions in California and across the US.
“We work closely with our fleet operators to make the transition to EVs smooth and seamless,” said Paul Gioupis, co-founder and CEO of Zeem Solutions. “We handle the infrastructure, charging, maintenance and depot operations, while achieving an EV operating cost near that of a typical diesel truck.”
“We were we able to start operating electric trucks immediately, without waiting for long vehicle lead times or building and installing any EV charging, which made it an easy and cost-effective decision,” said Kuehne+Nagel Senior VP Bill Kascel.
British retailer Marks & Spencer (M&S) and bp pulse have signed an agreement to install 900 EV charge points at around 70 M&S stores across the UK in the next two years.
The roll-out will significantly expand bp pulse’s network, growing the UK’s charging network and adding up to 40,000 kW of charging capacity to the UK’s EV infrastructure, says the company.
bp has plans to invest up to £1 billion in EV charging infrastructure in the UK—a step towards bp’s global ambition of having more than 100,000 chargers installed worldwide by 2030.
“We aim to provide fast, reliable and convenient EV charging to our customers that fits in with their busy lifestyles,” said Akira Kirton, CEO at bp pulse UK. “We are excited to extend our relationship with M&S to put charge points at their stores, growing our network even further.”
In recent years, the demand for high powered electronics has grown exponentially. With rapid growth in electric/hybrid vehicles, we are seeing that more electronics and power modules are needed to keep up with demand. However, EV/Hybrid vehicles are not the only applications driving this increased demand. Other major applications, such as rail traction, wind turbines, photovoltaic inverters and motor drives are also driving the increased demand. These applications are extremely demanding and are operating at high voltage and high current densities that must cope with high temperatures and harsh conditions. One of the key components for a highly reliable power module is an extremely reliable metal ceramic substrate. Substrate materials for these applications must have outstanding characteristics in terms of electrical, thermal, insulation, and mechanical performance during operation. To have a reliable system in place you need to have a compatible interconnection and assembly materials like solder paste, sinter paste, and wire bonding, to name a few.
Due to cost efficiency, Al2O3 based metal ceramic substrates, like direct copper bonded substrates are often used for power module manufacturing. Although, it is a cheaper solution, it is not always the best for certain applications, especially for high power modules. Al2O3 based ceramic substrates struggle to harness the full power of wide band gap semiconductors. In this instance, a superior substrate is needed. Silicon nitride (Si3N4) based metal ceramic substrates have been used in recent years for power module assembly. Its superior mechanical properties, such as bending strength, fracture toughness and thermal conductivity makes Si3N4 an attractive solution for a highly reliable, high power density module base. Today Si3N4 substrates are manufactured using active metal brazing (AMB) technology, which uses Ag-filled and titanium containing brazing pastes. Precious metal and complex processing steps drive the prices up for AMB substrates making it a more expensive option.
Heraeus Electronics has developed a solution that solves the cost and performance roadblocks previously described. It is a cost efficient, highly reliable Ag-free AMB copper bonding technology for joining nitride-based ceramics with copper foils. The material was developed using a technique where there is no requirement for using expensive vacuum-based brazing and longer process time. The product is named: Condura®.ultra, a Si3N4 Ag free AMB substrate.
Key Features
Outstanding reliability and processing (eg. Sintering, bonding, soldering…)
Cost efficient Si3N4 metal ceramic substrate
Enables thick Cu layers
Thinner ceramics vs. AIN possible for equal thermal
resistance
Thermal conductivity of Si3N4 ceramic:
> 80 W/m∙K
> 60 W/m∙K
Condura®.ultra is a cost-efficient Ag free AMB bonding technology for metal ceramic substrates that are suitable for high end applications. The cost reduction of Condura®.ultra is achieved by using a silver-free brazing technology combined with an efficient brazing process.
Below in Figure 1, it gives a look at the thermal shock performance of Condura®.ultra.
SAM pictures of 20 individual Condura®.ultra test layouts before and after thermal shock tests (liquid to liquid -65 ° C to + 150 ° C). No major degradation is visible after 8000 cycles. The red color indicates the etched isolation groove which is part of the test layout. In the event of delamination between copper and brazed metal due to thermal shock, the red color groove would broaden. This shows that Condura®.ultra qualifies to fully leverage the mechanical robustness of the Si3N4 ceramics in a similar manner as the Ag containing AMB technology.
Heraeus Electronics exhibits at PCIM Europe 10-12th May
Condura®.ultra will launch globally this year at PCIM Europe. PCIM Europe is the leading conference and exhibition for power electronics, renewable energy, and energy management, taking place in Nuremberg from May 10-12, 2022. While at the show visit Heraeus Electronics in Hall 6, Booth 322 to speak with our team about Condura®.ultra or some of our other new solutions for interconnects and die attach.
Join Heraeus Electronics Live at the e-mobility forum
On Tuesday May 10th at 11:20am CEST Heraeus Electronics will offer a sneak peak at our mAgic® Copper Sinter Paste with a presentation titled “ How near is copper sintering”. For more information, please visit us at the show or reach out to your local account manager.
On Wednesday May 11th at 12:50pm CEST Heraeus Electronics present on the Condura® product family and how Heraeus Electronics will meet rising customer expectations on the reliability, thermal performance, lifetime and price of metal ceramic substrates. Also in this presentation a new addition to the Condura® product line will be unveiled.
Before this decade is over, even conservative estimates indicate that at least two out of three cars produced in the world will be electrically powered. This figure accounts for both fully battery-powered and hybrid propulsion system vehicles.
There are some hard truths involved in engineering mobility for the future. Systems, safety, and performance are more critical than they’ve ever been and perhaps even harder to juggle. Connectivity, ADAS, and autonomous systems bring the promise of future innovation while also adding layers of complexity.
The hard truth is that designs must be engineered for reliability, lower weight, and flawless operation, while still managing to sparkle on the showroom floor.
In this e-Book, engineers from Celanese Engineered Materials take a look at some of the key EV battery components and the materials that will drive top performance.
Challenges abound
Designing a new electric vehicle battery can be a daunting task. There are so many factors to consider, from the materials used to the electrical capacity, to the temperature management of the battery. What’s more, the battery needs to be able to withstand a lot of wear and tear. The number of times it can charge and discharge is important too.
There are numerous other factors to consider when building an EV, but here is a short list of critical needs.
Power and charging: Inherent performance factors such as energy density, capacity, runtime, and others ultimately determine how far any electrically powered vehicle can travel on a single charge. Consumers have exhibited so-called “range anxiety” given the small number of charging stations available outside the home.
Safety: Li-ion batteries have the highest energy density and thus, the longest range. But they are temperature sensitive and prone to thermal runaway if overcharged or cooled insufficiently, so managing temperature is crucial.
Ability to withstand environmental conditions: Battery lifetime and range are affected by weather conditions such as rain, snow, road salt, heat, and road debris. Vehicle design and battery management systems play their parts in warding off these effects.
Cost: Batteries are the highest cost component in any type of EV – hybrid (HEV), battery (BEV), or plug-in hybrid (PHEV). This fact is the main reason EVs are still not priced comparably to ICEs (internal combustion engines).https://player.vimeo.com/video/769180681?h=d6a34a902e
Solving for the future of e-mobility
While there are many types of batteries on the market today, each with its own set of benefits and drawbacks, it’s essential to know which materials are best suited for your design.
If you’re an automotive design engineer who wants to learn how to make a more durable, faster-charging, and lighter-weight battery with advanced polymers, you’ll find answers in our e-book. It introduces the world of advanced polymers and their applications in automotive battery components. And it will help you understand how these materials work and why they make a difference in performance.
Note: As of November 1, 2022, Celanese has expanded its Engineered Materials business with the acquisition of the Mobility and Materials (M&M) division of DuPont. For additional information, please visit mobility-materials.com/
GreenPower Motor Company, a manufacturer of medium and heavy-duty EVs, has expanded its partnership with Malaysian bus manufacturer Gemilang International (GML) by agreeing to supply right-hand-drive heavy-duty Class 4 trucks and vans for fleet customers across Asia, the Middle East and Europe.
GML has more than 30 years of experience as a bus body manufacturer and has built bodies for various chassis companies, including MAN, Volvo, Mercedes-Benz and Scania. The company exports commercial vehicles to more than 15 markets worldwide, including Australia, United Arab Emirates, Singapore and Hong Kong.
“We have already delivered a right-hand-drive EV Star Cab and Chassis to GML, and will be delivering additional EV Star Cab and Chassis and EV Star Cargos,” said GreenPower CEO Fraser Atkinson.
Large-format lithium-metal battery developer Sion Power has announced plans to expand its existing manufacturing operations in Tucson, Arizona. The expansion is expected to be complete by 2026 and create over 150 jobs, primarily in engineering and other manufacturing-related positions.
The overall economic impact of the expansion is expected to be $341 million over the next five years, says the company.
Sion Power’s facility expansion will be equipped with fully automated battery cell production capabilities, including proprietary lithium metal anode manufacturing, cell assembly and testing.
“The global construction of battery manufacturing plants is occurring at a rapid pace, and the United States can’t be left behind,” said Tracy Kelley, CEO of Sion Power. “The expansion in Tucson will allow Sion Power to further our mission of scaling battery manufacturing from R&D to commercialization.”
Power management company Eaton has expanded the residential demonstration area within its Experience Center in Pittsburgh. As vehicle electrification continues to have a cascading impact on energy infrastructure, Eaton installed its latest smart breakers and EV charging infrastructure to show visitors how these technologies can contribute to home energy management strategies for the benefit of the grid.
Eaton’s Experience Centers provide a controlled environment for electrical contractors, builders, utility personnel and homeowners to observe product testing and performance, participate in live demonstrations and training courses, and learn about power management technologies from Eaton experts. The Pittsburgh facility showcases a range of solutions for residential applications, including a vehicle-to-grid (V2G) demonstration system, Eaton Green Motion EV 19.2 kW and 9.6 kW pedestal chargers, and multiple 9.6 kW smart breaker chargers inside and outside the building.
The V2G system demonstrates how homeowners can use bidirectional charging to lower their energy costs and carbon footprints. It includes Eaton enclosures, an eMobility Breaktor and a Bussmann series DC-fused disconnect switch.
“As customer demand grows for safer, smarter and more energy-optimized EV charging solutions, homeowners are turning to qualified electrical contractors, installers and home builders for EV charging infrastructure recommendations, as well as installation and maintenance best practices,” said Dan Carnovale, Director, Eaton Experience Centers. “Our goal is to take the mystery out of electrical power systems from utility substation equipment to the receptacle in your home, all while demonstrating the possibilities of using the Home as a Grid.”
“Given the widespread adoption of homes as energy hubs, Eaton continues to develop solutions to support the stability of electrical power and enable far more flexibility in how and when homeowners use electricity,” said Carnovale. “The residential demonstrations at our Experience Center show real-world requirements that help prepare professionals to support the demands of EV adoption.”
Georgia-based EV charging company EnviroSpark has completed a $10-million funding round led by Ultra Capital. The company announced its $5-million Series A funding earlier this year, bringing total outside investment to $15 million.
EnviroSpark plans to use the additional funding to expand its services and increase its employee headcount nearly fourfold.
EnviroSpark partners with property owners, utilities, nonprofits and governments to provide turnkey EV infrastructure solutions. The company continues to rapidly expand on its existing footprint of 5,800 chargers installed across the US and Canada.
EnviroSpark was recently awarded a federal government contract to design and install EV charging stations at federal agency locations throughout the Southeastern US. The General Services Administration contract includes a $500-million budget for the 13-state region.
“Given the US economy’s focus on the clean energy transition and EnviroSpark’s focus on top-notch operations and service, they are poised for success,” said EnviroSpark investor and former CEO of Georgia Power Paul Bowers. “EnviroSpark served as Georgia Power’s preferred partner during my tenure and I’m confident that they will continue to deliver for GPC and all of the utilities they serve.”
“EnviroSpark offers a unique and customizable turnkey solution to property owners looking to meet the rapidly accelerating demand from tenants for convenient and reliable charging,” said investor and former CEO of Post Properties Dave Stockert.
US-based bus manufacturer ENC, a subsidiary of the REV Group, will use propulsion and power management technology from BAE Systems in its new battery-electric and hydrogen fuel cell transit buses.
BAE Systems will supply its Gen3 power inverters and electric motors, Modular Power Control System (MPCS) and Modular Accessory Power System (MAPS) to ENC for use in its Axess Battery Electric Bus (EVO-BE) and its Axess Hydrogen Fuel Cell Electric Bus (EVO-FC).
The EVO-BE will include a Proterra Powered battery system, and the EVO-FC will have a 125 kW hydrogen fuel cell from Plug.
BAE Systems’ electric propulsion technology is developed and serviced at its facilities in Endicott, New York and Rochester, UK.
In Q3 2022, more than 77,000 tonnes of lithium carbonate equivalent (LCE) were deployed in the cells of recently sold passenger plug-in vehicles globally, 70% more than was deployed in the same period the year before, according to Adamas Intelligence.
In the Asia Pacific region, LCE deployment rose 100% year-over-year in Q3 2022 to 49,000 tonnes, and over the same period there was a 91% increase in plug-in vehicle sales.
In Europe, deployment rose 18% year-over-year in Q3 2022 to 16,600 tonnes. There was a 4% increase in plug-in vehicle sales over the same period.
In the Americas, deployment rose 70% year-over-year in Q3 2022 to 11,300 tonnes, and over the same period there was a 42% rise in plug-in vehicle sales.
In Q3 2022, 58% of all LCE deployed onto roads globally was attributed to China, 13% to the US, and 6% to Germany. Together, these three countries captured 77% of the global market, up from a combined 71% in Q3 2021.
In Q3 2022, 59% of LCE units deployed onto roads in passenger plug-in vehicles were derived from lithium carbonate (compared to 54% in Q3 2021) and 41% from hydroxide (compared to 46% in Q3 2021). This indicates that LFP and NCM 5-series cells continue to gain market share from high-nickel batteries that use lithium hydroxide, like NCM and NCA.
As of Q3 2022, there are 537 unique passenger plug-in vehicle models available for sale globally (and 749 versions of those models), per data from Adamas. But the Tesla Model Y alone accounted for more than 10% of all LCE deployed onto roads globally in Q3 2022 and for more than 15% in combination with Tesla Model 3.
EV startup Canoo has delivered its new Light Tactical Vehicle (LTV) to the US Army for analysis and demonstration.
Canoo says the electric LTV is engineered for extreme environments and includes stealth configurations. It incorporates carbon Kevlar for strength without added weight and is designed for passenger ergonomics and battery safety.
Canoo’s LTV has a proprietary all-wheel drive system that provides up to 600 hp of power. To meet the demands of off-road environments, it incorporates air springs, a raised suspension and 32-inch all-terrain tires.
According to the company, the new LTV can be converted from a pickup to a flatbed truck, a cargo vehicle and more. It can easily carry standard-sized plywood, construction and oversized materials, as well as tactical equipment or attachments for required missions.
Canoo’s proprietary modular attachment system enables the LTV to have mission-specific configurations. Flatbed walls can quickly be exchanged for many other types of mounts, including racks, ramps, storage boxes, tents or tactical systems.
“The LTV is another milestone proving the power of our technology and how it can be used, even in tactical situations,” said Tony Aquila, Chairman & CEO at Canoo.
Electric vehicles (EVs) are becoming an increasingly popular choice for environmentally conscious consumers. These vehicles run on electricity rather than fossil fuels, making them a clean and efficient transportation option.
One of the biggest benefits of EVs is their reduced environmental impact. Because they don't burn fossil fuels, they produce zero emissions while driving. This makes them a much cleaner option than traditional gasoline-powered vehicles, which contribute significantly to air pollution and climate change.
EVs are also generally more cost-effective to operate than gasoline-powered vehicles. Because electricity is typically cheaper than gasoline, it can be less expensive to drive an EV over the long term. Additionally, EVs require less maintenance than gasoline-powered vehicles, which can save money on repairs and maintenance costs.
There are several different types of EVs available, including all-electric vehicles (EVs that are powered solely by electricity) and hybrid electric vehicles (EVs that have both an electric motor and a gasoline engine). All-electric vehicles have a limited range (typically around 100-300 miles), so they may not be suitable for long road trips. However, they can be charged at home or at public charging stations, making it easy to keep them powered up.
Hybrid electric vehicles have a longer range because they have a gasoline engine as a backup. They can switch between the electric motor and the gasoline engine as needed, depending on the driving conditions.
EVs are becoming more widely available and affordable as technology improves and production increases. Many automakers now offer a range of EV models, and governments and businesses are investing in infrastructure to support the growth of the EV market.
Overall, electric vehicles are a promising option for those looking to reduce their environmental impact and save money on transportation costs. While they may have some limitations compared to gasoline-powered vehicles, they offer many benefits and are an increasingly viable transportation choice.
Charging infrastructure: One of the challenges of electric vehicles is the need for charging infrastructure. While it is possible to charge an EV at home using a standard electrical outlet, it can take several hours to fully charge the battery this way. To charge an EV more quickly, it is necessary to use a higher-voltage charging station. These stations can be found at public locations or installed at home, and they can charge an EV in as little as 30 minutes to an hour. The availability of charging stations can vary depending on location, so it's important to consider this when deciding whether an EV is a practical option.
Battery lifespan and replacement: The batteries in electric vehicles typically have a lifespan of around 8-10 years, depending on the make and model. While EV batteries are designed to last for many years and miles, they will eventually need to be replaced. The cost of replacing an EV battery can be significant, so it's important to consider this when deciding whether an EV is a good choice.
Range anxiety: One of the concerns that some people have about EVs is the limited range of the battery. While most EVs can travel 100-300 miles on a single charge, this may not be sufficient for long road trips or for those who need to drive long distances on a regular basis. If you anticipate needing to drive long distances frequently, an EV may not be the best choice.
Upfront cost: While EVs can be cost-effective to operate over the long term, they can be more expensive to purchase upfront than gasoline-powered vehicles. This can be a barrier for some consumers, especially if they are considering an EV as a second or third vehicle. However, many governments and automakers offer incentives to encourage the adoption of EVs, which can help offset the upfront cost.
Performance: Electric vehicles are known for their smooth, quiet operation and instant torque, which makes them fun to drive. They can also be very fast, with some models capable of reaching high speeds. However, because the weight of the battery adds to the overall weight of the vehicle, EVs can sometimes feel heavier and less agile than gasoline-powered vehicles.
Overall, electric vehicles offer a clean and efficient transportation option that can be cost-effective to operate over the long term. While they may not be suitable for everyone, they are an increasingly viable choice for those looking to reduce their environmental impact and save
Ford has invested an additional £125 million in its Halewood plant in the UK, bringing the total investment to almost £380 million and increasing its capacity by 70%.
This latest investment secures employment for another 500 people and increases annual production from 250,000 to 420,000 units, says the company.
Ford hopes to sell 600,000 EVs in Europe by 2026, meaning roughly 70% of them will be powered by components produced in Halewood.
“Ford is a global American brand, woven into the fabric of Europe for more than 100 years and a major employer here at Halewood for almost 60 years,” said Kieran Cahill, VP of Ford’s European Industrial Operations. “Our vision in Europe is to build a thriving business by extending leadership in commercial vehicles and through the electrification of our car range. Halewood is playing a critical part as our first in-house investment in EV component manufacturing in Europe.”
In the electrical/electronic world, the terms interconnect and disconnect both refer to a means of joining two sides of a circuit together. The subtle—and entirely informal—difference is that an interconnect is directly or manually operated (inserting a plug into a jack, for example) while a disconnect is indirectly or automatically operated, for example the moving contacts in a light switch, circuit breaker or contactor, or the fusible link in a fuse (which is “operated” by opening up from overcurrent). This might seem to be a distinction without (much of) a difference, but a notable one is that the typical interconnect uses contacts that slide past each other, whereas most disconnects use contacts that meet (or pull apart) directly, with minimal to no sliding component to their motion.
Generally speaking, the four main design objectives for high-power interconnects and disconnects are: 1) minimizing contact resistance; 2) resisting mechanical wear from each operational cycle; 3) preventing contact degradation from all operational and environmental causes (e.g. arcing, corrosion, etc.); 4) maintaining safety during both normal and abnormal (fault) conditions.
One of the first considerations is how to bring the contacts together to close the circuit (i.e. the “make” operation), and how to pull them apart to open it (i.e. “break”). In the case of plug and socket type interconnects which conform to a standard, such as CHAdeMO or J1772 for EV charging stations, these details are going to be dictated to the design engineer, with precious little room for deviation even in those all-too-frequent cases in which the standard doesn’t quite anticipate all the challenges imposed by physical reality.
It’s perhaps less well appreciatedthat contacts designed for high current can become progressively more resistive from repeatedlymaking/breaking under no-load conditions (aka “dry switching”).
The next parameters to consider are the circuit conditions, primarily: the voltage and current to be handled; whether it is AC or DC; and whether the circuit is predominantly resistive, inductive or capacitive in nature. While it’s probably obvious that making or breaking under heavy load should be avoided if many cycles of operational life are desired, it’s perhaps less well appreciated that contacts designed for high current can become progressively more resistive from repeatedly making/breaking under no-load conditions (aka “dry switching”). This is due to the buildup of sulfides and/or oxides on the contact surface, which requires either a sufficient current flow during the make operation to punch through them (read: a sufficient voltage difference), or a strenuous sliding/wiping action, which will itself result in accelerated wear of the contact surfaces (a case in which the cure is arguably as bad as the disease). Otherwise, when circuit conditions are predominantly inductive, it is the break operation that is most stressful, because of the arc that will jump across the opening contacts if it is not suppressed with a snubber of some sort (e.g. a metal oxide varistor, resistor-capacitor circuit, etc.).
Conversely, when circuit conditions are predominantly capacitive—as typically applies to the input to a charger or an inverter—then it is the make operation that is most hazardous, due to the extreme current which will flow if the voltage difference is not reduced with a pre-charge circuit just prior to closing the contacts (with, for example, a smaller relay and resistor wired across the main contacts).
The final circuit condition that greatly affects interconnect/disconnect design is whether AC or DC is being switched. AC of a given power level is far easier to deal with, because the voltage and current periodically cross through zero (e.g. 100/120 times per second for 50/60 Hz, respectively), which will tend to extinguish any arcs that might form during the break operation (there is less benefit to switching AC during the make operation, since it is practically impossible to synchronize the closing of a contactor—much less a human inserting a plug into a socket—with the zero-crossing of the AC voltage waveform). Note, however, that at a high enough voltage and/or with an insufficient contact separation distance (exacerbated by separating the contacts too slowly during the break operation), mains-frequency AC will happily re-strike an arc 100/120 times per second. Two solutions often employed in higher-voltage disconnects are magnetic blowouts, in which magnets placed on either side of the contacts push the arc away as they separate; and filling a sealed contactor with sulfur hexafluoride, a gas with a dielectric strength approximately 2.5 times higher than air (however, it is a potent greenhouse gas—the “no free lunches” rule strikes again).
Two solutions often employed in higher-voltage disconnects are magnetic blowouts and filling a sealed contactor with sulfur hexafluoride, a gas with a dielectric strength approximately 2.5 times higher than air.
As is so often the case in engineering, optimization of one parameter comes at the expense of another, and so it is with electrical life vs mechanical life vs corrosion resistance for the contacts in an interconnect or disconnect. For plug-and-socket interconnects (by far the most common type), the contact surfaces will almost certainly slide past each other during the make/break process, and this is where the heartache of mutually exclusive goals begins. The first pair of contradictory goals is that minimizing the contact resistance requires the contacts in plug and socket to meet with high force, but that then makes the plug too difficult to insert or remove from its mating socket. For plugs/sockets that are only infrequently mated—such as for a dryer or electric range—straight blades in the plug that must force apart curved leaf-spring contacts in the socket are acceptable, despite requiring 10 kg or more of force to mate in the case of dryer and range interconnects.
Eaton’s ‘Breaktor’ device for EVs combines the high-voltage protection device functions of fuses, pyro switches and contactors into a single coordinated device
An AC charging station port on an EV handles a similar maximum amount of power to an electric range (i.e. 240 VAC / 50 A), but requiring a similar 40+ pounds of force to insert the plug into its charging port would not be welcomed by any EV owner (to say nothing of the fact that the combo would wear out after 100 or so uses). One practical solution is to use round pins that mate with sockets that are a cylindrical hyperboloid in shape (strongly resembling a “Chinese finger trap”), as this will achieve a much higher total contact area between each pin and socket, while requiring even less insertion/removal force. A cylindrical hyperboloid socket is much more expensive to manufacture, of course, but this is a case in which the less expensive solution—straight blade interconnects—is simply unworkable, rather than merely not as good.
To continue the theme of trade-offs, improving the mechanical and/or corrosion-resistance properties of a contact material tends to come at the expense of lower conductivity, so it is very common to make the contact out of one metal or alloy, and then plate another metal/alloy onto it. For contacts that can be protected from the atmosphere (e.g. inside a sealed contactor), the emphasis can shift from achieving the highest corrosion resistance to minimizing both metal transfer from arcing and contact resistance, but the contacts in the plugs and sockets of EV charging stations must contend with all three requirements: good corrosion resistance; good mechanical fatigue and wear properties; and low contact resistance (albeit with less need to minimize material transfer from arcing…or that should be the case, anyway).
The highest conductivity (aka lowest bulk resistivity) is obtained with silver, of course, but the best corrosion resistance is obtained with the platinum group metals, or gold. While silver can be a good choice of contact material inside of a sealed contactor, or for bolted-together connections (such as bus bars), it too readily forms oxides/sulfides (aka tarnish or patina) if exposed to the atmosphere/pollution, and it is also quite a soft metal in its pure form, so it wears poorly and tends to deform, rather than spring back, from impact, meaning it’s not the best choice, whether contacts come together directly or slide past each other. Alloying silver with copper greatly improves the mechanical properties compared to either pure metal, but then the conductivity drops below that of pure copper (around 92% IACS for sterling silver). Of the platinum group metals, palladium is most commonly used both in alloys and as a plating for contacts, as it has excellent corrosion resistance and decent hardness without being too brittle, making it a preferred choice for sliding contacts. On the minus side, its conductivity is much worse than that of pure copper (16% IACS) and it is exceptionally expensive, of course. Rhodium has better conductivity than palladium (about 38% IACS), and is much harder as well (about 3x to 4x), but that also means it is more brittle, so perhaps it’s an even better choice for sliding contacts, rather than those that meet with considerable impact force.
Sensata Technologies’ GXC and MXC series of smart contactors
The final consideration is operational and environmental safety, which mainly consists of not exposing live conductors, if applicable, and not catching on fire due to overload, an external ignition source, arcing, etc. The latter objective can be met by only using materials which are non-combustible and which won’t melt at too low a temperature. Operational safety can be much more difficult to achieve for interconnects that are handled by a person, like the charging plug for an EV fast charger, compared to devices located inside a charger or inverter, such as a contactor or a fuse. A decent—if not foolproof—solution is to simply shield the contacts on the live side of an interconnect in two dimensions (so that sliding along the third axis is still possible). This is the strategy employed by every electrical outlet found in the home, after all, and though it has arguably stood the test of time, it is still possible to stick a foreign object into the outlet terminals, or only partially insert the plug into the outlet, thereby exposing the live circuit to a child’s (or a fool’s) fingers. Consequently, a more thorough solution is to use retractable shutters over the pins, sockets, or both, which automatically retract upon insertion of the plug into its receptacle.
Lastly, the means by which wires are terminated into their respective contacts is critical to overall safety (and efficiency). At low currents, a spring-cage, or “screwless,” clamp is a very reliable solution, as the spring ensures that the wire strands are pressed against the terminal cage despite vibration or cold-flow displacement of the copper. Screw clamps are used at current levels from a few amps up to around 10 or so, because they can apply far more compressive force for a given housing volume. From 10 amps to several hundred, crimping a lug onto a stranded wire cable is the termination of choice, as it has the lowest possible resistance, good resistance to vibration, and good to excellent corrosion resistance. For extra longevity and corrosion resistance, lugs can be filled with dielectric grease before inserting the cable and crimping it. The grease is forced out from every interface between the cable wires and the lug wall, effectively sealing off the crimped area from air, liquids, etc. Much the same would be accomplished by soldering the cable into the lug, but that is never done—at least not for cables that will be subjected to flexing or vibration—because the solder causes embrittlement and fatigue cracking of both itself and the copper wires over time. Definitely not something you want happening to a DC fast charger cable carrying a few hundred amps!
Fleets tested Volvo VNR Electric Class 8 tractors for three years: Here’s what they learned.
Large commercial trucks and other heavy equipment have run on diesel fuel for many decades now. Requirements for more aggressive emission after-treatment and the hardware to achieve that add cost and complexity for fleet operators. Rising fuel-economy standards during the 2020s will do the same. But today, heavy trucks remain a diesel world.
That’s about to change. The far higher volumes of carbon dioxide per mile from heavy trucks make them an obvious target for zero-emission powertrains. Some makers suggest hydrogen fuel cells will be the way to go; the most promising application seems to be long-haul trucking with few or no stops.
However, heavy-duty electric trucks from traditional makers have started to hit the market. Publicity magnet Tesla said it delivered its first battery-electric Semi tractor on December 1. It has now received a Certificate of Conformity for the Semi from the EPA. Among its first announced customers, back in December 2017, was Pepsi, which reserved 100 of the trucks and plans to use them in the California regions of Modesto and Sacramento.
Volvo Trucks (now a separate entity from the carmaker Volvo owned by China’s Geely) knew several years ago it wanted to get into the electric truck business. Its first model was an electric adaptation of its conventional diesel-powered VNR tractor. It had a 264 kWh battery pack powering the tractor’s twin motors with more than 4,000 lb-ft of torque and a range estimated at up to 150 miles.
To figure out how to make electric trucks work in practice, the manufacturer, the state of California, and a wide array of partners—more than a dozen all told—launched the Volvo LIGHTS (Low Impact Green Heavy Transport Solutions) project in 2019 to test its first electric Class 8 tractors with multiple Southern California operators. The goal was simply to figure out, for a small number of trucks in different uses, what worked, what still needed work, and what practical hurdles existed for battery-electric trucks in a previously all-diesel fleet.
The group’s final presentation lists 18 insights Volvo and its partners gained from the project.
Altogether, the group’s final presentation lists 18 insights Volvo and its partners gained from the project. Many were covered in detail during a day of presentations and site visits for partners and media held this past August in Ontario, California.
New partners for fleets—and lots of them
The overall lesson, repeated frequently, was that multiple entities must come together for electric heavy trucks to succeed—including many that fleet operators haven’t dealt with before—and that this has to happen early in the planning process. Put another way: Plan first, order trucks second.
The first lesson, one that may seem obvious, is that electric trucks are better suited to some routes than to others. “Identifying ideal routes is key to success,” says the LIGHTS group’s final report, and the learnings were underscored by the fleet operators taking part.
The starting point was routes of 80 to 150 miles a day, but more factors came into play than sheer range. Topography (lots of hill-climbing or mountainous terrain) and weather (extreme heat or cold) have significant impacts on an electric truck’s effective range. In this case, Southern California has fairly temperate weather, and parts of the region are quite flat. But the fleet operators need to work together with the truck-maker and its dealerships to identify the most promising initial routes for electric trucks.
Driving style also matters. Experienced diesel drivers will need training for electric trucks to maximize use of regenerative braking, which can recapture 5 to 15 percent of a battery’s energy.
Driving style also matters. Experienced diesel drivers will need training for electric trucks to maximize use of regenerative braking, which can recapture 5 to 15 percent of a battery’s energy. While semi drivers can be a conservative group, those willing to become the first EV drivers in their fleets soon came to appreciate some side benefits of electric trucks.
Driver Elvis Alvarado and fleet manager Hector Banuelos openly discussed the pros and cons of the first-generation VNR Electric tractor tested by NFI. Among its advantages were smooth power delivery, lack of continuous gear shifting, less vibration (“I could write on my notepad,” marveled Alvarado), and the ability to retain cabin cooling or heating when parked in no-idle zones. Also, he noted, he needed much less time to check over the truck’s powertrain before runs—and he didn’t smell like diesel fuel after the workday.
As for challenges: The VNR Electric tractors were quiet enough that yard and port staff often didn’t hear them coming, requiring extra alertness on the driver’s part. Range anxiety was a continual factor, and Banuelos suggested it could be hard to get the quoted 150 miles to cover two round trips to a port and back in a 10-to-12-hour shift. He expects the 250-mile range of second-generation VNR Electric tractors to provide a comfortable margin in many more circumstances.
Dedicate a project manager to EVs
It’s crucial that any operator have at least one person charged with the responsibility of coordinating all aspects of adding electric trucks to a fleet. He or she should be prepared to work closely with primary contacts at the electric utility, perhaps multiple government agencies, any contractors hired to upgrade electric service or install charging equipment, and more.
It’s crucial that any operator have at least one person charged with the responsibility of coordinating all aspects of adding electric trucks to a fleet.
While a truck-maker and its dealer can help in identifying suitable routes and matching them to electric trucks, that’s only the start of the process. Shepherding the planning, permitting and construction of the needed infrastructure, training for fleet operators and drivers, and ensuring that trucks don’t arrive until their charging is live…all of those tasks should be centralized in one person with clear authority and lines of reporting.
It can well become a big, complicated, sprawling job. But for ambitious fleet staff, it’s experience that can make them far more attractive to future employers.
Charging infrastructure installs vary, a lot
Electricity is everywhere, including in or near the fleet depots and parking lots where heavy trucks spend much of their time. But the time and cost of installing the needed charging infrastructure for electric trucks can vary enormously: “from a few thousand dollars for lower-power chargers to millions of dollars for high-power chargers” that can deliver up to 1 megawatt each.
The time and cost of installing the needed charging infrastructure for electric trucks can vary enormously.
It’s hard to generalize on costs and effort, but factors include a fleet’s electrical load profile (how much power needs to be delivered, and when), the size and cost of the chosen charging hardware, the existing electrical infrastructure at the sites chosen, and even the distance of a site from high-voltage service lines.
One major tradeoff is what level of DC fast charging is required to allow trucks to fulfill their duty cycles. A 150 kW charger may recharge a battery pack to 80 percent in about 2.5 hours, while a 250 kW unit can cut that to 1.5 hours—at the cost of longer installations, more infrastructure work, and higher charging station costs. It all depends on the needs of the routes being covered by the electric trucks.
As the report notes, “A more powerful charger may entail longer installation timelines and higher capital investment costs in the form of civil and electrical upgrades that are difficult to justify during an early demonstration stage but can provide a faster charging experience.”
Faster charging is typically more expensive because it requires an electrical system to operate at peak power, for which utilities levy higher demand charges, since it puts more stress on the electric grid. However, these higher energy costs can often be managed through a sophisticated EV service platform for smart charging.
For fleet operators, concepts like demand charges and charging management software are entirely new. When it comes to diesel fuel, the only significant variables are how far away it is and what it costs per gallon. The small number of operators who run mixed-fuel fleets (diesel and gasoline, or diesel and natural gas) will understand these tradeoffs better.
It’s crucial to plan for future upgrades—by wiring for higher power or more stations than needed at launch—to prevent the need to retrench and add wiring down the road.
Starting out, fleets may want to mix high- and low-power DC fast charging to see which meets the needs of different duty cycles and routes. But if asphalt must be trenched, electrical service must be upgraded, and new cabling must be run into parking lots, it’s crucial to plan for future upgrades—by wiring for higher power or more stations than needed at launch—to prevent the need to retrench and add wiring down the road.
Expect the unexpected, plan on delays
With luck, not every electric truck launch will take place amidst a global pandemic, as the Volvo LIGHTS project did. But the process of installing charging infrastructure will inevitably encounter delays, as all the participants stressed. The earliest possible contact with both the electric utility and local land-use and permitting authorities is crucial, especially if this is the first local project with megawatt-scale charging.
Those early meetings will help “calibrate expectations” for the fleet operator about how fast a project can realistically progress. The LIGHTS partners advised EV fleet adopters to build in extra time before the vehicles themselves are scheduled to be delivered—because a large electric truck without the ability to charge it is little more than a parking-lot paperweight.
Emissions come way down, and so does cost, but …
There’s no longer any question that electric trucks have significantly lower lifetime carbon footprints than any trucks running on fossil fuel. Furthermore, like passenger EVs, their carbon emissions per mile will fall over their lifetimes as the grids they’re charged on decarbonize.
The LIGHTS team had the Volvo VNR Electric tractor assessed by a team at the University of California, Riverside on a heavy-duty dynamometer. Combined with a life-cycle assessment (LCA) of the electric truck’s well-to-wheel impact, the Volvo VNR saved 65 percent of total energy and 81 percent in fossil energy, and it cut lifetime greenhouse-gas emissions and criteria pollutants (hydrocarbons, nitrogen oxides, carbon monoxide and soot) by more than 80 percent compared to a baseline diesel truck.
The cost equation is trickier. Today, battery-electric Class 8 tractors still have a higher lifetime cost, due entirely to the initial purchase price of a heavy-duty vehicle with a huge battery (264 kWh for the first-generation VNR Electric). An electric Class 8 tractor still carries roughly twice the price of a comparable diesel version. That in turn raises insurance costs as well. The LIGHTS team found that, once acquired, the electric truck had significantly lower operating costs per mile—but that didn’t make up for the higher purchase cost.
The LIGHTS team found that, once acquired, the electric truck had significantly lower operating costs per mile—but that didn’t make up for the higher purchase cost.
Several speakers highlighted the need for more federal, state and local incentives to encourage use of zero-emission heavy trucks.
From the report: “The federal government and some states offer dedicated grant programs for BEVs and related infrastructure, but the funding currently available isn’t sufficient to support widescale market deployment. In California, several utilities offer incentive programs to buy down the capital equipment cost for their customers, a model other states should consider emulating.”
Onward and upward
Now that the Volvo LIGHTS program has officially concluded, what’s next? Volvo has launched an updated version of its VNR Electric truck, with increased ranges of up to 230 or 275 miles from battery packs of 375 and 565 kWh. Those trucks are now arriving at selected dealers in California and elsewhere. The company expects to sell hundreds of them, which will provide more real-world experience in a broader array of use cases.
Moreover, to expand beyond depot charging—the focus of the LIGHTS project—Volvo Group announced in mid-November that it would partner with the Pilot Group. That company, which operates more than 750 Pilot and Flying J travel centers across North America, plans to install high-performance charging infrastructure at selected locations over the next few years. This is a step that, so far, Tesla has not taken for its own Megacharger standard.
Mack Trucks, also owned by Volvo Group, updated its own electric tractor in March. The latest Mack LR Electric uses a standard 376 kWh battery, with twin electric motors producing 330 kW (448 hp) and identical peak torque to the VNR Electric. The Mack electric truck is part of a $10-million program by the New York State Energy Research and Development Authority (NYSERDA) to reduce emissions by using zero-emission trucks in the Hunts Point neighborhood of the South Bronx, which suffers from some of the worst air quality in New York City.
Meanwhile, participants in the LIGHTS Project expect to continue experimenting with electric trucks. They’ve seen some of the pitfalls, understand the process better, and are now considering how those experiences will let them scale from one truck to, say, ten, and then more. Stay tuned.
This article appeared in Issue 62: Oct-Dec 2022 – Subscribe now.
Participants in the Volvo LIGHTS Project were: California South Coast Air Quality Management District, Volvo Group, Dependable Supply Chain Services, trucking fleet NFI, the Ports of Los Angeles and Long Beach, Southern California Edison, TEC Equipment, Shell Recharge Solutions (née GreenLots), University of California, Riverside College of Engineering, Rio Hondo College, San Bernardino Valley College, Reach Out and Calstart.
Funding of $90 million for the project came from the California Climate Investments, which contributed $44.8 million of Cap-and-Trade money. The balance came from the project partners.
Volvo Trucks provided airfare, lodging and meals to enable Charged to bring you this first-person report.
