Bring Your Own Cord

Credit: Flo / itselectric

On Tuesday the EV charging company itselectric announced its partnership with Hyundai and the NYCEDC to deploy curbside Level 2 chargers at two Brooklyn locations as part of a two-month pilot program. Most of the coverage takes note of the fact that these will be the first chargers in North America to feature “a fully detachable charging cord” (see here, here and here), but that undersells what I think is a pretty exciting development: finally, we are getting BYOC (bring your own cord) chargers.

BYOC is a common-sense solution to some of the biggest challenges associated with wide deployment of AC public charging infrastructure (read: not DC fast charging). BYOC  has long been the standard in the UK and broader Europe and the benefits are substantial.

1. BYOC significantly reduces the initial cost –and unsightliness– of AC chargers. While not extremely expensive, nondetachable cables that are made for commercial use are built quite robustly and cost more than a cord for individual use. And because these commercial cords need to be kept off the ground when not in use, the chargers themselves tend to be bulky and intrusive. BYOC changes all that. Instead of tall cable management towers that are a street eyesore, we can build chargers right into existing street infrastructure. For example, since 2020, Siemens has worked with Ubitricity to retrofit thousands of lampposts in central London with EV charge points.

2. BYOC also significantly reduces the cost of charger maintenance. One of the main challenges in keeping EV chargers operational is ensuring the charging cables and connectors remain in good condition. Wear and tear accumulates on these components from normal use as well as from deliberate abuse, and proactive maintenance is required to keep everything operating properly. Even the simple act of connecting and disconnecting the cable from the car slowly wears out the connector itself. 

The cables, because they need to be able to reach all points of a car, are necessarily quite long and unwieldy–we’re talking 25 feet, as long as a garden hose. This means that the cables often rest on the ground and, if not put away correctly, can be run-over or otherwise damaged. The perceived political character of going electric, combined with the high copper content of the cables, means the cords are also often targets of deliberate vandalism or theft.  

These factors make operating a widespread public charging network in a city a particularly daunting prospect. What municipality or charging operator would want to be responsible for maintaining thousands of long charge cables in a city where one man destroyed 42 LinkNYC screens? 

3. BYOC eliminates a major point of failure from the charging experience. As any EV owner can tell you, one of their biggest complaints is the unreliability of the public charging network. For homeowners and renters who have a dedicated place to park and charge every night, this is only an occasional annoyance. For city dwellers whose cars spend most of their lives parked curbside, this can be a make-or-break problem. If the majority of the energy going into your vehicle is coming from public chargers, the dependability of those chargers will be critical to your purchasing decision and your satisfaction as an owner.

For all the reasons already mentioned, charger cords are susceptible to damage. BYOC makes the charger that much easier to maintain and puts the cord into the hands of owners who can easily store it in the trunk of their vehicles and keep it out of harm’s way. This model also ensures that any act of vandalism affects a single user at a time, rather than the entire user base of a given charger.

Urban AC charging doesn’t get as much press as DC fast charging but is an equally crucial piece of the EV charging challenge. It’s very exciting to see a simple, cost-effective solution to the problem of curbside charging being deployed in NYC. Here’s hoping the pilot is successful and can serve as a model for smart citywide curbside charging nationwide.

Size Matters PT.2: Farewell Chevy Bolt

Chevy Bolt 2016 - 2023

Last week I wrote on the dismaying trend toward ever-larger vehicles in the US and expressed the hope that the transition to EVs might help shift our preferences to something more sustainable than the trucks and SUVs that most Americans now purchase.

So much for that. Yesterday, GM announced that it is shutting down production of the Bolt EV (and its very slightly larger EUV sibling) and converting the Bolt plant in Michigan to instead assemble Blazer and Equinox EV SUVs. 

GM’s exit from the small-EV space is disappointing. The Bolt was an extremely competent, if unexciting, little car. On paper it did everything well. The Bolt EV and EUV start at around $26k, meaning they can be had for less than $20k when factoring in the federal tax credit. This is less than half of the average purchase price of a new vehicle in the US. They also have a decent range of around 250 miles, depending on trim. They have all the expected safety and technology features like lane keep assist, Apple carplay, wireless phone charging, and heated and ventilated seats as standard. At 3500lbs, they are pretty light for an EV, but still have enough space for four 6ft adults and cargo. They are even reasonably quick with a 0-60 time of 6.7 seconds. 

If the Bolt models have any major flaw, it's that its fast charging is capped at 55kW, making them decidedly inconvenient for road trips (charging from 10-80% would take about an hour). That said, for most owners this would be a factor pretty infrequently. As a city car or a commuting runabout, they are ideal. They even sold reasonably well, with GM planning on selling 70,000 of them this year, certainly making them GM’s current best selling EV. 

The larger Ultium platform EVs are newer technology and will likely sell in larger numbers than the Bolt. These vehicles will definitely offer greater range, power and size, but will also cost twice as much as the Bolt. 

While I knew it was unlikely that consumer preferences would shift overnight to smaller, more efficient vehicles, I had hoped that the Bolt’s compelling combination of capability and affordability would have persuaded GM to bring the advantages of the 800V Ultium architecture to a Bolt-sized vehicle, in addition to the larger SUVs that are its bread and butter. It seems a shame that consumers will no longer even have the option to buy a small, quietly competent, well-priced EV. 

Size Matters: Rethinking the Trend Towards Larger Vehicles

These two trucks have the same sized bed. Source Reddit

Last week at the New York Auto Show I checked out the unveiling of the new Dodge Ram REV, Dodge’s very first electric pickup truck. As with the launch of the Ford F150 Lightning in 2021 and the Chevy Silverado EV last year, Dodge’s milestone was met with much excitement and the implicit question of whether this new Ram is a ‘real’ pickup. 

These days a ‘real’ pickup is expected to have a very high payload rating, towing capacity, and off-road ability, while serving simultaneously as a luxury family-hauler. A modern F150 Platinum or King Ranch, for instance, has the comfy ride and leather interior to rival the Lincoln and Cadillac brands, but can still tow up to 14,000 lbs, carry a literal ton in the bed in certain trims and, with the right tires, can also be very capable off-road.

All these added features have made modern pickups much more expensive than their predecessors. But putting that aside, this capability comes with other costs: in particular, size and weight. A typical super crew (4-door) F150 weighs around 5,000 lbs. Even when compared to similarly equipped pickups from the 90s, these trucks are longer, taller and heavier by a significant margin. 

Judging from the wild popularity of pickups, Americans are willing to pay for the poorer gas mileage and other inconveniences that accompany this enormous added weight. Light trucks (a category which includes larger SUVs as well as pickups), made up a staggering 79% of new vehicle sales in 2022. Ford famously stopped selling sedans altogether in 2019 and only offers a single ‘car’ these days, the Mustang. The F-series has long been the best-selling vehicle in the country, and in recent years pickups in general represent as much as 20 percent of US auto sales. But when you’re talking about EVs, inefficiency isn’t something that can just be shrugged off with a credit card at the pump. Until batteries improve and chargers become more ubiquitous, EV owners will pay heavily for blocky profiles and every unnecessary pound in the form of shorter range and greater charging anxiety.

There is a reason that the early hybrids, the Toyota Prius and Honda Insight, had virtually identical profiles: aerodynamics. When miles per gallon was the main selling point of the vehicle, trading aesthetics for efficiency was an obvious choice. For EVs the argument is even stronger. The efficiency of the vehicle now not only affects how much you will spend to fuel it, but how far you can travel from home without charging and how long it takes to charge on long trips. The best batteries can charge from 10% to 80% in about 18 minutes these days, but living with that is drastically different if your range is 200 miles versus 400 miles. 

As a general matter, the problem of excess weight will create challenges as EVs take over simply because EVs tend to be heavier than their ICE counterparts (consider, for example, the structural integrity of older parking garages designed for much lighter vehicles). Batteries are inherently less energy-dense than gasoline, and so, to achieve comparable range, more space and mass must be dedicated to them. For a typical passenger vehicle, this means an additional 500 lbs or so. And this weight penalty scales with the size of the vehicle, so we can expect large pickups to weigh as much as several times their ICE equivalents. The F150 lightning weighs about 1,000 lbs more than the closest ICE analog. And the new GMC Hummer EV, with its 212 kWh battery, weighs over 9000 lbs, which is 3,000 lbs more than the Hummer H2 that preceded it and fully double the weight of a standard F150. As for the newest member of the EV pickup family, the Ram: When I saw the 230kWh battery announced for the 500mi range version, I realized that this latest iteration of EV pickup is likely at or around 10,000 lbs. 

As the owner of a 2,000-lb 1990 Mazda Miata, this is terrifying. Having my head at bumper height of modern pickups is scary enough, but doubling their weight and giving them the ability to accelerate as fast as a Ferrari make future roads sound like a pretty scary place. But no doubt Dodge decided the huge battery was necessary to ensure decent range–the F150 quite famously lost half its range when towing a large load in testing. 

That brings me to the part of the EV weight problem that is particular to pickups. It’s not just that EV pickups are necessarily heavier than their ICE equivalents. The problem starts with the ICE pickups themselves, which have become unnecessarily heavy over the last two decades.

A pickup used to be a work truck. From their inception with a version of the Model T in the 1910s, through much of the 1990s, pickups were utilitarian workhorses. (Their labor connotations were so strong that even now, apparently, some homeowners’ associations do not allow pickups to be parked in driveways.) They had spartan interiors. Their durable, heavy load-capable suspensions made for a bumpy ride. Their bench seats didn’t recline. It wasn’t until 1993 that leather seats were even an option in the F150 with the launch of the now iconic Eddie Bauer trim, which set the tone for what was to come. Dodge followed suit in 1994, and Chevy waited until a 1999 redesign to catch up. 

Today, a pickup is expected to be both functional and fabulous–so fabulous that most pickup owners buy their trucks despite barely using their capability. On average, 75% of owners used their truck to tow once a year or not at all, a similar percentage go off-road, and 35% of owners are unlikely to use the bed even once in the course of a year. So we have a huge percentage of drivers on the road with very capable, very heavy, very expensive vehicles that are increasingly purchased with very long, onerous loans. These are owners whose actual needs would be better served with a sedan, minivan or small SUV, as they could simply rent a big pickup on the rare occasions when they need to tow or haul something significant. For owners who do need to use the bed more than occasionally, my guess is that a smaller, more efficient pickup like the new Ford Maverick would serve the needs of many just as well, and do so while getting 40+ mpg. (That said, I should note that the Maverick, by far the smallest of the four main pickups Ford currently offers, is three inches longer than a short bed F150 from the 90s, and seats two more people.)

The pickup craze isn’t an accident. Among other things, the federal government has long incentivized the purchase of these huge trucks, along with very large SUVs. Famously, the Section 179 deduction allows owners to deduct as much as $27,000 of the vehicle’s value as long as at least 50% of its use is for business purposes and the GWVR (Gross Vehicle Weight Rating, or fully loaded weight) is between 6,000 and 14,000 lbs. This deduction was initially put in place in 1986 when passenger-oriented vehicles very rarely were that large, but it has since become an oft-exploited loophole used to allow small business owners to reduce the cost of everything from Range Rovers to Rolls Royces. Being quite popular, and often actually used for business purposes, F150s and the like are major beneficiaries of this tax incentive. On top of this, the way our fuel economy standards are structured, larger vehicles are subject to more lenient efficiency standards simply because they are larger. 

Which raises a big question–perhaps the question–as the EV boom gets underway. Do we want the same cars in battery-powered form? Or should we think of the EV revolution as an inflection point in the history of automotive machines–as an opportunity to integrate consumer wants, climate needs, and the best of our smart tech into a new vision of the modern American car.

An interesting case study of optimizing for efficiency can be seen in the Hyundai Ioniq 5 and Ioniq 6. Both vehicles are roughly the same size, and utilize identical batteries and powertrains. The Ioniq 5 wears a fairly traditional hatchback/small SUV body, whereas the Ioniq 6 has a sedan shape that is highly optimized for aerodynamic efficiency. In fact the Ioniq 6 may have the lowest drag coefficient, .21, of any true production car. This difference in shape allows the sedan to extract 58 miles or ~20% more range than its blockier cousin. This means it will cost 20% less to fuel, and in practical terms charge 20% faster as well. If Hyundai had announced a new battery that improved range by 20%, it would be hailed as revolutionary. This efficiency gain should be met with similar applause. A more extreme example is Mercedes’s recent concept vehicle, the EQXX. This highly streamlined sedan boasts a drag coefficient of .17, allowing it to travel over 620 miles on a 100kWh battery. As a point of comparison, the current class-leading Tesla Model S travels 405 miles on the same battery capacity. We could have recognized these gains with ICE vehicles, but chose not to because gas was cheap and cars are often a more emotional than rational purchase. 

With time, batteries will become more energy dense, lighter, and faster charging. EV chargers will also become more ubiquitous and able to support higher charging speeds. But until that day, we have real incentive to make cars more aerodynamic, more efficient, and responsive to our actual rather than imagined needs. The constraints of current EV technology and charger availability are real, but they also heighten the rewards for creative solutions (and possibly some consumer soul-searching).

At the very least, maybe the transition to EVs will force the question of whether downsizing and optimizing for efficiency is something we should do more broadly. If the government really wants to encourage people to buy smaller and more efficient vehicles, EV incentives alone won’t be enough. Reforming the tax and fuel economy standards for all vehicles to disincentivize (or at last stop incentivizing) the ever heavier American vehicle fleet will be critical to reducing the environmental impact of our driving, whatever fuel is powering it.

EV Illiteracy: How to Spot Bullshit

On Saturday, while waiting to check out at Whole Foods, I saw a sleek magazine from Centennial Spotlight slotted in the rack between towers of bottled electrolyte water. The magazine was ambitiously titled “The Complete Guide to Electric Cars”, and the blurbs on the front promised not only "expert reviews " of some of the newest EVs, but also tips on "maximizing range" and "home charging." Intrigued, I bought a copy.

That was a mistake. The “guide” was riddled with glaring factual inaccuracies. I just wish I could say I was surprised.

We have a serious EV literacy problem in this country. Now, let me be clear: I’m a car guy. Actually, I’m interested in just about anything on wheels. I was 15 when I took apart my battered 1972 Datsun 240Z and put it back together again, and in the two decades since, I’ve owned and retooled more bikes, motorcycles, ATVs, and cars than I can count. But as a car guy, I understand not everyone shares my interest. Certainly most people don’t have the time to learn the intricacies of inverters and battery management systems. Yet if the United States is to successfully transition from gas to electric cars, a lot more attention needs to be paid to basic consumer education about how EVs work–and, more generally, about how to think about charging, power, and energy.

It is understandable that many of the concepts behind buying and living with EVs would be foreign to most drivers today, as most have never driven an EV, let alone looked for the best charger in their neighborhood. But despite their best efforts, even intrepid EV owners can be stymied by the lack of information and even misinformation about how to maintain their cars, manage the costs of charging, and improve their day-to-day driving experience. 

Dealerships are the average consumer’s first point of entry into the EV world, but they are often ill-equipped to educate consumers on how to purchase or use EVs, and sometimes have to be dragged kicking and screaming into supporting them at all. So consumers are likely to turn to published resources, whether online or in print, to find the answers to their questions.

Cue the talking heads and “complete guides.”

The first few pages of this magazine were an innocuous history of EVs dating back to 1835. But this was followed by a particularly problematic glossary section that contained so many errors that I covered my copy with notes.

Nothing could be more flagrant than the magazine’s nearly constant confusion about the difference between energy and power and repeated mix-up of the units used to measure each. For example:

Level 1 - This is the slowest and least recommended way to charge a vehicle, as it is merely an AC plug connected directly to a standard household outlet. It provides a scant 2.3 kilowatts per hour (kWh)

In fact, most circuits in the US can provide only 1.5kW, but the main issue here is that a kWh is a measure of energy, not of power. Charging power is measured in kW, not kWh.

Level 3 - Known as a DC charger, this is currently the fastest way to charge an electric vehicle with speeds of up to 250kWh.

Again, DC chargers today  can be as fast as 350kW, and again, a kWh is a measure of energy, not of power. 

Charging from home, consider the average cost of a kWh to be about $0.15, so an EV with a 66-kW battery would cost about $10 to fully charge at home

This one is particularly frustrating because it gets  the first unit right, but misses the landing on the battery size (which should be kWh). 

Confusing energy with power is not a minor mistake. In the context of an EV, energy describes the amount of electricity that is stored in your battery and determines how far your car can travel, while power is the rate at which that energy is removed from the battery to propel you forward. So, other things equal, a car with greater battery capacity (typically measured in kilowatt hours, or kWh) can travel more miles, while a car with an electric motor with a higher power rating (measured in kW) can accelerate more quickly.

Put another way, power is the amount of electricity used at any instant, as reflected in the units used to measure it: for example, a kilowatt is a thousand watts, and a watt is simply a joule of energy used per second. Energy is simply power multiplied by time. Putting the two concepts together, a space heater requiring 1kW of power running for 1 hour uses 1 kWh of energy. To compare the units to something more familiar, 1kW is equal to about 1.34 horsepower.

An EV charger rating is a power rating: it represents how fast electrical energy can be transferred from the charger to your EV's battery (at least in theory, even if not in fact). But you are billed for your charger use based on the amount of energy you put in your battery, which makes paying per kWh for an EV a lot like paying per gallon for a run-of-the-mill internal combustion engine (ICE) car. An EV owner might have a 100kWh battery, pay $.30 per kWh to charge at a 150kW public station, and go from 20% to 80% charged in about 30 minutes.

Some other egregious errors:

The PHEV(Plugin Hybrid Electric Vehicle) is the most commonly seen type of hybrid vehicle and is usually what first comes to mind when people use the term ‘hybrid car.’...Nonetheless, plug-in hybrid vehicles remain the most common and popular solution for American Drivers

This is the exact opposite of the truth. In fact, HEV (non plug-in Hybrid Electric Vehicles) were first to market and so synonymous with the archetypal Prius that Toyota had to add ‘Prime’ to the model name to distinguish the plug-in version. More to the point, even as recently as February, HEVs outsold PHEVs four to one. The section then goes on to list the Audi e-tron as an example of a PHEV. But that’s wrong again: the e-tron is Audi’s sub-brand for its full electric models. 

Level 3 Charging - Also known as DC charging, it charges at 480 volts with a direct current (DC) plug. It takes 30 minutes to charge an EV with a 100-mile battery.

This makes no sense as a way to think about charging speed.  For starters, charging voltage for a DC charger can be anywhere from 200V to 1000V, and charging time depends on the car and the rating of the charger itself. That said, what car has a “100-mile battery”? I’m aware of only one EV with such a limited range that can fast-charge, the Mazda MX-30. Presumably, the author meant a car takes 30 minutes to get 100 miles of range. But in any event, a more accurate statement would be “typical cars can charge to about 80% in around 30 minutes.” And depending on the car, 80% can mean a range of anywhere from 100 to 400 miles.

SAE Combo CCS - An enhanced Level 2 plug that supports DC charging levels of up to 170kW.

CCS Combo is the de facto standard Level 3 plug and supports charging levels of up to 350kW currently.

The magazine goes on to talk about upcoming tech from a company called uBeam that will “charge the battery via Wi-Fi with electromagnetic waves.” This vision–of “a safe way of beaming power to your devices,” from a company that has promised and failed to make the idea work for even phones since 2011–is preposterous. (To be clear, the so-called WiFi option is not the same as close-contact inductive charging, which has been around for a while.) The reference, by itself, makes clear this magazine is not to be taken seriously.  Now, I know that because I am an engineer working in the space. But you shouldn’t need a degree to filter out misinformation from a magazine whose entire contents are dedicated to EV education. Putting out this level of misinformation is borderline reckless, and will inevitably do more harm than good to consumers trying to educate themselves about what is likely the second-largest purchase they will ever make. 

Charge Port Placement: Can’t We All Just Agree

Many of my articles thus far have been relatively technical, but this one covers a much simpler issue: We all really need to agree on where the charge port is placed on a car.

An odd legacy of gas fillers is that we’ve come to terms with them being placed on either side of the car. But it’s not as if this is of no consequence. Gas stations take up a larger footprint than they would if we were consistent. Often you will see cars doing a bit of a shuffling act to get to an available pump. Most of this nonsense could be avoided if, at least as a country, we could pick a side, as we have with steering wheels and turn signal stalks. 

EVs have not only inherited this problem but have given it another degree of freedom. Charge ports can be located just about anywhere–not only on either side of the vehicle, but also in the front or rear. The Nissan leaf has the port in the middle of the hood, while the F150 Lightning has it just in front of the driver’s door. Meanwhile Tesla has always placed its charge ports on the driver's side rear.

Inconsistent charge port placement has real consequences. Chargers that are designed to serve all vehicle types need cables that are 20 feet or longer in order to reach the potential port locations. This doesn’t sound like a big deal until you realize that the cables themselves are often the bottleneck when it comes to charging speed. Increasing amperage requires either thicker or water-cooled cables. Both solutions are expensive, and the former–thick copper cables–are unmanageable when 20 feet long. 

Tesla neatly solved this problem for itself by putting the charge port in the same place on every car it produces. This relatively obvious solution meant that Superchargers could have cables that were only 6 feet long: either thick, passively cooled cables carrying 400A, or water-cooled  cables handling 600A or more. This has allowed Tesla to charge 400V cars at 250kW, a feat that no other charging provider has been able to replicate. 

Other charging providers have been saddled with the responsibility of catering to a range of cars manufactured with charge ports in every imaginable place, and thus have needed to deploy extra long cables, which have typically been limited to 350A even when using active water cooling. This means that even some fancy 350kW stations are only capable of charging at 175kW when charging the standard 400V cars. 

Another problem is arising now that Tesla is opening up the Supercharger network to other vehicles. Because of the seemingly random charge port placement, it is possible that a mix of vehicles could tie up all of the charge post/parking space combinations while only using half of the posts themselves. It seems that Tesla is tackling this problem by creating a new charge post with a slightly longer cable and placing it between spaces rather than in the center of the space, but all this hassle could be  avoided if we could just agree to put the port in the same place. From a technical standpoint, standardizing port placement wouldn’t pose a significant burden on EV manufacturers and is a common sense step for the industry to take.

Stay tuned: in a future article I’ll move beyond the location of charge ports and discuss flaws in the ports themselves and why we have committed to an inferior charging standard. 

NEVI: BUILDING FOR YESTERDAY? PT.3 - POWER SHARING

Part three of a multi-part series discussing the shortcomings of the recent NEVI final rule and what that may mean for EV charging in coming years.

In my first NEVI article I discussed how the NEVI final rule, the most important set of government standards for determining how EV infrastructure is deployed along the nation’s corridors, disregarded the issue of cord amperage and in this way missed the opportunity to set a real baseline for what constitutes ‘fast’ charging. In my second article, I explained that the NEVI-specified minimum site size is too small to serve even current demand and that incentivizing “make-readies” would have helped ensure sites are equipped for easy expansion to meet inevitable future demand. Here I put aside the question of future efficiencies that could have been captured and stick to analyzing the constraints the NEVI places on the efficient use of even the power that is supposed to be available to EV drivers today. 

The problem starts with the NEVI’s undue emphasis on charging speed ratings (which, as I have discussed, are more theoretical than actual because the NEVI does not account for the voltage of the typical EV and the amperage of the cord). The first principle to understand when discussing speed ratings is that they specify the maximum charging speed, not the average charging speed for a vehicle over a charge session. That matters because, for technical reasons I get into below, a car battery can charge at or near the maximum charging speed for only a relatively brief portion of the period required to get a full charge. In fact, most EVs today spend a relatively small amount of time charging at a speed above 100kW, let alone above 150kW. The efficient response to this reality would be to allow chargers to dynamically share power between multiple cars, so that at any given point in the charge session the charger dedicates to a car only as much power the battery can take and reallocates the rest. 

But one of the NEVI’s principal requirements is that each of the minimum four ports at a station must be capable of delivering 150kW simultaneously for the whole duration of a charge session.

The provision is well-intentioned and presumably designed to ensure a fast and consistent charging experience wherever an EV goes. But what it signifies in practice is that for a lot of the charging time, much of the hardware and grid capacity that is dedicated to each charger will go unused. Thus sites that adhere to the NEVI’s minimum requirements standards as written will experience wasted power capacity and unnecessarily high hardware, construction, and electricity costs. 

First things first: car batteries charge on a curve. In fact, depending on the car, they charge on many different curves, as reflected in the below chart (from P3 Group):

Many factors affect charging speed, but the most important to consider is the fundamental chemistry of lithium ion batteries. As shown in the chart, whatever a lithium battery’s charging curve, generally the lower the battery’s state of charge (SOC), the more power it can accept. In plain English, the deader the battery, the faster it charges. As the battery becomes more full, the rate of charge slows down. A simple way to picture the charging process is as follows. The lithium ions need to move from one electrode in the battery to the other. But those ions need to find cavities in the electrodes to fit into. When the battery is at a low (SOC) most of these cavities are empty so it is easy for many ions to find a home at the same time. The fuller the battery becomes, the more “searching” each ion has to do to find an available spot, with those very last spots at nearly 100% SOC taking quite a long time to find. As you might notice with your laptop or phone, going from 10% to 20% charge typically happens very quickly, whereas 90% to 100% takes far longer. The same principles apply to the chemically similar, far larger lithium batteries in electric vehicles. 

As can be seen in the charge curve graph above, maximum charge rate can typically only be maintained until around 40-50% SOC, after which the maximum power the battery can take tapers off gradually. It is for this reason that charge times are often quoted from 10%-80% SOC rather than going to 100%, because that last 20% can take as long as the previous 70%, and in practice drivers are unlikely to wait around that long. 

There are other factors that impact charging speed, many of them temperature-related. The curves above represent a battery and charger in ideal conditions. Lithium batteries are sensitive to temperatures that are too high or too low, and so being at either extreme can impact charge rate. Like humans, batteries tend to work best in the 70-80 °F range. The battery management system (BMS) that controls charging in an EV knows this and is constantly balancing between keeping the battery at the right temperature and using up energy to do so. Most EVs are capable of actively heating and cooling their batteries to bring them to the ideal temperature, but this uses a significant amount of energy, so batteries are often allowed to stray outside of the ideal range to save energy. Some vehicles, like Teslas, feature what is called “smart preconditioning,” where the car recognizes when you have input a charging station as a destination and brings the battery up to temp just in time to charge, trading a bit of energy for a significant time savings once you start charging. If a car arrives at a charging station with a very cold battery, it might spend 10-20 minutes charging at only 10kW while the battery is brought up to temperature. Similarly, the charge rate suffers at the upper end of the temperature spectrum, and on hot days you can often hear the vehicle’s fans running at full blast to keep the battery cool and maintain charge rate. In fact, Rivian just patented chargers with fans to blow cool air vaguely in the direction of the vehicle to enable faster charging.

All that is to say that there are myriad reasons why a vehicle at a busy four-port charging station will not be able to accept the full power that the charger is capable of delivering for the full duration of the charge session. So the energy it isn’t using could theoretically be used by any of the other three cars plugged into the station. But the NEVI doesn’t permit that kind of sharing except where the available power exceeds 150kW.  

Tesla enabled power sharing between pairs of chargers at the inception of its Supercharger program because it recognized that it was unlikely that two cars would each be requesting power from a charger at the then-100kW max at the same time, or for very long. These chargers were designed to dynamically share 150kW total between two charge posts (rather than, say, capping the charge posts at 75kW each). As the batteries got larger and chemistry improved to allow them to charge faster, Tesla moved to V2 Superchargers (150kW split into two 120kW posts), then to V3. V3 actually represented a step change in power sharing: not just power sharing between posts fed by a cabinet, but between multiple cabinets at a particular site. 

Each 350kW charge cabinet was directly connected to three or four charge posts, each charge post had a 250kW max. But these multiple cabinets could be connected by a common DC bus, meaning that in practice the power was shared between all posts at the site, not just between the ones connected to a particular cabinet. To play this scenario out, an eight-stall site could have charge posts that would each be capable of delivering 250kW reliably, but instead of having a connected load of 2mW as would be required if those were individual 250kW chargers, only 700kW would be required from the utility. This allows for a smaller transformer, as well as smaller switchgear and conduit. This also means that the utility is more likely to be able to provide the necessary power without major (sometimes infeasible) modifications of the existing electrical distribution infrastructure. Put another way, with this power-sharing set-up, for a given electrical load you could install roughly three times the number of chargers that in practice would be about as fast (for all the battery-chemistry reasons stated above), on the same electrical connection.

The same general principle applies at a more bare-bones, NEVI-compliant, four-port site. NEVI requires a charge capacity of at least 600kW at every site for those four 150kW ports. A site with the same charge capacity but five or more ports is not compliant under the NEVI and therefore ineligible for federal funds. That’s a shame, because a few additional ports would allow more vehicles to be serviced at a given time, without significantly slowing down charging for any particular vehicle.

The NEVI-mandated installation of DC fast chargers that do not share power (at least below the quite-high threshold of 150kW) impacts more than the number of EVs that can be served or the size of transformers, switchgear and conduit. It impacts the cost of electricity itself. That’s because two potential cost-drivers on a utility bill are the capacity and demand charges. Put simply, capacity is the maximum power you have the ability to use, demand is the maximum instantaneous power you actually use. Having dedicated 150kW chargers necessarily maximizes capacity charges, and has the potential to increase demand charges for very little benefit. This means that even for the same amount of electricity, used at roughly the same time of day, in a power-sharing scenario the electricity bill could be significantly lower. These savings could be passed on to the consumer.

During the NEVI notice and comment period, commenters highlighted the many potential benefits of accommodating power sharing. But the official response, reflected in the final rule, was that “the requirement that each DCFC must simultaneously deliver up to 150 kW, as requested by an EV, was retained as a minimum requirement to provide a standard, reasonably high level of charging service.” This stance is particularly frustrating considering that, as I covered in my first article, that “high level” of charging service is not guaranteed for the majority of EVs by the NEVI standards because of the agency’s decision to ignore certain actually critical determinants of charging speed, like cord amperage. 

And so we find ourselves in a scenario where 150kW of dedicated power has become the de facto standard for the building of fast chargers, despite being of dubious value in practice–that is, as experienced by current EV owners who will use that dedicated power for a fraction of their charging session (if at all). Allowing more dynamic power sharing would allow for more chargers to be built more quickly on available power, and would reduce not only construction costs but operating costs as well. Sharing available power over a larger number of chargers also helps alleviate drivers’ biggest complaint with the charging experience and the subject of my next NEVI article: reliability.

Stepping on the Gas: Why Fuel Retailers May Be the Best Drivers of EV Adoption

EV charging is a tough business. But legacy fuel retailers are well-positioned to make it work. 

Direct current (DC) fast chargers, in particular, are not fast money. Capital expenditure is typically in the hundreds of thousands per site, while the margins made on the energy sold to drivers are cents on the dollar. Plus maintenance is a surprisingly high ongoing cost for any truly reliable site. The upshot is that even for the busiest sites, the payback period on the capital invested can approach a decade. 

So how to make EV charging an appealing business proposition? Two main approaches have emerged and promise varying degrees of success.

The first and primary approach has been for original equipment manufacturers (OEMs)–that is, car makers–to subsidize the installation and use of chargers. The most obvious example is Tesla, which has made its Supercharger network free for Tesla owners for much of its history, and has paid for the network’s construction and operation through vehicle sales (and ever-increasing stock value). Similarly, OEMs that don’t own chargers can simply pay third-party charging operators to provide their vehicle owners free or subsidized charger network access. Ford, for example, offers its customers 250kWh of complementary charging at Electrify America (EA) stations (which were created as part of VW’s deal with the U.S. government after its emissions scandal and are, somewhat ironically, funded through the sale of diesel vehicles). Hyundai offers two years of free charging at EA stations.

The second approach has been government or utility subsidy. Local, state, and quite recently federal government agencies have offered funding to cover the capital expenditures associated with installing EV chargers. This is helpful and perhaps necessary, especially in this early phase when EV adoption is just ramping up and all sites may not be fully utilized right away. Drastically reducing the ROI timeline allows EV charging operators to expand more quickly, and also incentivizes them to build sites that aren’t immediately busy and generating maximum revenue but are necessary to enable long-distance travel. These sites are critical in encouraging widespread EV adoption, and so the subsidies make sense, but we can’t expect the government to foot the bill in building these stations forever.

Recently a third option has emerged: using advertising on chargers to supplement the charging revenue.These chargers incorporate a large screen to show ads not only to those charging, but also to passersby. While this model makes operating a charger much more financially sound, it makes the most sense in dense areas like cities where a high volume of people can be expected to view the ads. It doesn’t necessarily work for corridor locations where fewer people will be able to see them.

The challenges facing EV charging should sound familiar. There is another player in the transportation industry that faces high capex, extremely low margins, and long ROI timelines: fuel retail. 

Gas stations cost even more to build than EV charging stations, and with gas stations so ubiquitous that they are often across the street from each other, competition on pricing is stiff. Most stations make only a few cents per gallon on fuel. What makes these businesses profitable? The food and convenience stores attached to them. One regional fuel retailer told me in 2018 that they are willing to sell fuel at a loss to be the cheapest in town, so that drivers will fuel up with them, and hopefully buy a sandwich and a coffee while they're at it. Costco similarly breaks even on fuel, and uses its cheap fuel stations to coax shoppers into its stores and onto its membership rolls.

So it makes all the sense in the world that companies like 7-Eleven are getting into the EV charging game. These companies are accustomed to long payback periods on high capital investments, and crucially, they have the experience and supply chains to make money from drivers waiting to charge. During my time at Tesla, convenience stores were among our most enthusiastic partners. They were more than happy to host Superchargers, even though their parking lots were often quite small, because they knew there was a high probability that drivers would come in for a snack while they waited.

These retailers are positioned to scale quickly. They already have the land required, and largely in the right locations to serve drivers needs. They are experienced in building complex construction projects and dealing with the knotty planning, zoning and permitting required to get projects approved in the first place. They have the maintenance infrastructure to keep everything in top condition. Most importantly, their incentives are aligned with those of EV drivers. Because they make their money on convenience retail and not fuel, they have every reason to invest in a sufficient number of the fastest chargers available to maximize the number of customers who visit their store, and to maintain them so that drivers return. They don’t lose much in creating redundancy and building chargers that might sometimes sit empty. The charger itself can be a loss leader, as long as the charging experience is so good it brings drivers to their property.

So while the government is currently kickstarting EV charging to get the flywheel moving, it will be more sustainable for the 7-Elevens, Sheetzes and Walmarts of the world to lead the charge in the coming years. The true value to businesses to be gained from charging is not a markup on electrons, but the time and money drivers can be expected to spend on their property while they charge. Fuel retailers should be preparing for the future by applying the skills and infrastructure they already have, and EV charging companies should be looking to the past for lessons on how to make financial sense out of charging when the subsidies dry up. 

NEVI: BUILDING FOR YESTERDAY? PT.2 - FUTURE PROOFING

Part two of a multi-part series discussing the shortcomings of the recent NEVI final rule and what that may mean for EV charging in coming years.

In my last article I discussed how the NEVI final rule, the most important set of government standards for determining how EV infrastructure is deployed along the nation’s corridors, missed the opportunity to set a baseline for what actually constitutes ‘fast’ charging. Here I begin delving into why  the charging sites built to meet NEVI standards will not be sufficient to meet EV owners’ needs today, let alone those of the near future. 

Determining the appropriate number of charging posts to satisfy demand is admittedly a difficult problem. From my time at Tesla, where I ran the charging infrastructure team for the Northeast US, I know only too well that many factors play into the calculation. How many vehicles do you expect to service during peak times? How much energy will they require on average? How quickly will they be able to charge? How reliable are the chargers you are installing and what degree of redundancy are you aiming for? How much do your chargers cost and how many charge sessions per month will be required to pay them off in a reasonable amount of time? How do you expect all of these factors to change over the lifetime of the site, which is likely decades?

These are still the early days of EV infrastructure, and so these questions can’t be definitively answered but nevertheless should be considered when designing a site. At Tesla, I was equipped with very detailed information about the cars, chargers and usage patterns and was able to reasonably assess how many chargers would be needed to serve demand for the next few years. Though I had this information at hand to ‘right size’ any given location, when a site host would ask how many spaces for charging I wanted, my answer was always ‘as many as you will give me’. And even at this stage, we insisted on building sites with no fewer than eight stalls.

This was our approach even though when I joined in 2016, the EV market was a fraction of what it is today–then Tesla’s global fleet was just over 100,000 cars, whereas nearly a million EVs were sold in the US in 2022 alone. Despite not even earning direct revenue from the chargers until 2017, Tesla was willing to invest in large sites because it was building for the long term, the agreements it signed with site hosts spanned decades, and crucially, because it understood three fundamental rules of EV charging. 

The first rule is that for a given location, every additional charger you install reduces the average cost per charger of the site as a whole. This is mainly due to the fact that for most charging stations, it is the infrastructure on and under ground rather than the chargers themselves that drive much of the cost. Significant drivers of cost include laying conduit; pulling conductors; pouring pads for transformers, switchgear and charging posts; landscaping; paving; and line painting, and these are costs that don’t change much whether you are building a 4-stall or 10-stall site. By spreading this infrastructure cost over a larger number of chargers, you get more chargers per dollar spent. Tesla knows this and builds sites with at least eight and as many as one hundred chargers. This is one reason why Tesla’s cost per charger is so much lower than that of other charging providers. 

The second rule is that even if you don’t need the additional chargers now, they will almost certainly be useful within the design life of the site. It doesn’t take much imagination to picture more than a dozen cars an hour needing to charge at a given site along the Interstate within the next few years, which is roughly the best-case scenario for a four-post, 150kW site that meets the NEVI standard, even accounting for the fact that future vehicles should be able to charge faster than today’s cars (on this, see my last post). Critically, more stalls also means more redundancy. That’s important because as any EV driver can tell you, chargers don’t always work. According to a recent study, as many as a quarter of them are nonfunctional at any given time. While EV supply equipment manufacturers and operators certainly need to improve that statistic, the consumer pain of a nonfunctional charger can be mitigated in the meantime by building larger sites that provide more redundancy. 

The third rule is that it is essentially just as difficult to add more chargers to an operational site as it is to build a new one from scratch. For starters, you often have to go through permitting, planning and zoning again, a process that can take years. Even assuming that process can be simplified for public corridor chargers, a site undergoing expansion would need to be closed down for at least a few days or weeks, and in most cases the transformer and switchgear would need replacement. The site would also need to be excavated again to lay new conduit and pour new concrete pads and relandscaped when the work is done. 

The upshot of these rules is that, when viewed in the long term, it always makes sense to build larger sites. What’s more, they should be built to support future capacity. 

Let me explain. It is understandable that EV charging operators would have a different approach to charging than Tesla. Tesla sells cars, not energy, and so is not as focused as a charging operator might need to be on shortening ROI timelines for each site. For much of its history, Tesla was losing money on every use of its public chargers but invested in quality chargers anyway because it recognized that a fast, reliable charging experience helped sell cars. For most charging operators, the incentives are reversed. A busy site is a profitable one. Keeping drivers waiting to charge does not affect their bottom line, while building chargers that sit underutilized does. For this and other reasons, it might not be reasonable for the government to mandate that charging operators install excess charging stations that may not be fully utilized for years in all cases. There is, however, a middle ground that NEVI could have utilized to prepare the country for the inevitable expansion of EVs and their increasing demands for public chargers: incentivizing and subsidizing make-ready.

Simply put, make-ready means making the site ready for future installations, and includes building infrastructure to support more chargers to make future expansion of the site quick, cost effective and easy. In practice this means when the initial four chargers are installed, they would be fed by a slightly larger piece of switchgear containing spare breakers  to support another four or more chargers. While the sitework is done, empty conduit would be run to additional spaces in the parking lot. All this conduit would be a little larger than is strictly necessary so that larger conductors could later be installed to support even faster chargers in the future, should that become the new standard. These steps represent minimal increases to construction costs when the site is initially being built, but would be far more expensive to go back and do later. This small amount of additional investment would future-proof each charging site, not only facilitating its ability to deploy more chargers quickly and easily, but simplifying upgrades to existing chargers. 

During the notice and comment period, FHWA fielded submissions underscoring the importance of encouraging or even requiring make-readies from environmental and industry groups alike (for example, see comments from RMI, Plug in America, Oncor, and Clean Fuels Michigan). By instead making the minimum site size four chargers and not providing any incentive or guidance on how to design sites to be cost effectively expanded in the future, the NEVI final rule has locked us into small sites that will be congested almost immediately, and will require costly, time consuming upgrades well inside their design life.