Charging ahead in 2019

What's it like to own an electric car in France?

Around 2009 (10 years ago) I made the decision that I wouldn't buy another new/used gasoline powered car, but I would keep my current car running until I could buy a practical fully electric vehicle (EV). My wish was finally granted about 5 months ago and I hope to shed some desperately needed light on this unnecessarily mysterious technology so that people can make informed decisions about how best to transition to an EV. First I'll give some history, explain general engineering concepts, briefly talk about the various candidate cars, and finally share what is involved in the daily life of owning and driving an EV. The "appendix" at the end shares some specs for competitors and puts theoretical numbers into perspective through application.

Even if you don't agree about the dangers of climate change, oil will be depleted in around 50 years (according to BP's 2012 Statistical Review of World Energy). That means it'll continue increasing in price exponentially, and we should probably be saving what's left of raw crude oil for making plastic materials instead of burning them up for transportation and expelling CO2 into the environment (intensifying the atmospheric greenhouse effect and acidification of the oceans).

History

But enough about why you should (must) switch to an EV, let's talk about some background info on this relatively simple technology. Electric motors have been in practical usage for nearly two centuries (1830's). It shouldn't be too surprising that this preceded common usage of combustion engines by about 40 years, because electric motors are so much more mechanically simple than combustion engines. Since that time, electric motors have been optimized and improvements are still being made today (see modern advances in axial flux motors). EV's have also been around since 1870, but they've never been practical for one main reason -- their batteries.

Batteries

Improving electrical energy storage is a technological barrier that we've slowly been chipping away at, but batteries would still need to double in energy density to resemble something comparable to a modern gasoline powered car. I'd argue that this is very possible and will probably be achieved in 5-10 years, at which point, electric cars would easily be able to achieve a range of 600km on one charge. In the past this was largely thanks to portable devices like smart phones and laptops which have been pushing the technology forward, but now that multiple car manufacturers are taking this competition seriously, it's attracting attention. I believe the next new billionaire will be the person leading the way to design a fast-charging, lightweight, long-lasting electric battery.

Designing batteries compact enough to fit into a car is just one obstacle; the 2nd issue with batteries is their charging rate. Again, this is something that will likely be doubled in the same 5-10. There is already a very wide range of charging rates available, but their price range matches accordingly. Battery capacity has been increasing while their costs simultaneously decreasing, and EV's will likely surpass gasoline cars in both categories easily by 2030 (especially if you account for savings in fuel costs). Later I will give some specific examples and numbers, so stay tuned!


Lastly, batteries are designed to operate mainly between 20-80% of full capacity. In fact, they typically charge more slowly above 80% and supposedly degrade the battery slightly more quickly when charged to 100% frequently or when allowed to drain to nearly 0%.

Maybe someday we'll circumvent the need for batteries entirely if we can provide the power directly like trains do.

About me

During my undergraduate studies in 2007, I participated in an overseas summer internship at BMW in Munich, Germany where I learned about the latest M3 V8 engines on the assembly line. Upon returning home I also took a college course on Internal Combustion Engines (ICE) to solidify my theoretical background with them. They were fascinating and I enjoyed learning about their complexities. Two years later around 2009 during my masters degree I dove deeply into studying gas turbo-machinery using computational fluid dynamics (CFD) where I learned that turbines offered an obvious efficiency improvement over ICE's, but were not practical for use in small vehicles. Very recently during my 2016 post-doc I started learning about combustion modeling (mainly for turbines) and throughout all of this experience one thing has stood out out for certain -- these mechanical machines are overly-complicated and rather inefficient at turning fossil fuels into rotational energy/motion. There are better ways to achieve motion than burning oil. It's been difficult for society to wean away, mainly driven by the fact that the fossil fuel industry is so entrenched in its ways and expects ever increasing returns on their investments. The industry has setup a worldwide conglomerate of infrastructure to support securing fossil fuel sources, then its extraction, transportation, refinement, and consumption. They've spent billions of dollars making it as convenient as possible to provide fuel for your vehicle and ensure that you'll keep needing it, hiding (out-of-sight and out-of-mind) the background process as much as possible, and have also earned an exorbitant amount of profit in doing so.

I'm really glad that I didn't end my education at a bachelor's degree. The difference between the focus on course material was immense. It was less about preparing students to work for profit, crunching numbers, and memorizing methods/equations, but more focused on critical thinking skills to solve big societal challenges. Or at least I felt that it enabled me to do so. Just at or before the start of my PhD, I enrolled in three separate courses: renewable energy, solar power, and environmental engineering, and I was made aware of various future possibilities (which I'll share in more detail later). That's when I made the critical decision and commitment to never buy another gasoline vehicle again, even if it meant spending a little more.

My gasoline car

My first new car was a 2002 Volkswagen GTI, and it came installed with a turbo charger that gave it an impressive 100hp (horsepower) per liter (of engine displacement). This is a measure of power density, meaning that a small 1.8L (4 cylinder) engine producing 180hp could fit into a pretty small car (by American standards because the GTI is actually one of the larger models in Europe). This was pretty impressive at that time, made possible because a turbo charger improves an ICE by bringing it closer to the thermodynamic cycle of a gas turbine. Most recent cars have focused on fuel efficiency rather than acceleration, so while I was able to achieve a consistent 28 miles per gallon (MPG) equivalent to 8.4 l/100km with my good driving habits, most econo cars today can achieve twice that or approach 3x that if they exploit a technology known as "regenerative braking."

Engineering Concepts

Feel free to skip this section if you already familiar with these engineering concepts.

Regenerative Braking

If you didn't know this already, one of the coolest things about electric motors is that they are ALSO electric generators! They can seamlessly switch between opposite roles, either

• Consume input electricity to produce an output torque
• Apply an input torque to generate output electricity

depending on whichever you need (vehicle acceleration or deceleration respectively). Most people understand intuitively that a motor consumes electricity to produce a torque (on car wheels to accelerate a car forward), but Regenerative braking is the opposite process of recapturing wheel motion (rotational kinetic energy) via an electric generator to re-produce electricity. This technology was successfully deployed in hybrid vehicles a decade ago with small batteries so that some of the energy during braking could be recaptured, stored, and used later to help re-accelerate the vehicle back up-to-speed, effectively increasing the city mileage by around 40%. This benefit is noticeable mainly in stop-and-go city driving, but has near-zero benefit on highways where braking is seldom used. This means that all EVs will natively support regenerative braking, as it adds almost no extra engineering requirements or costs. Electric trains have been using this technology for many decades because they don't need batteries, they just feed electricity back into the grid whenever they slow down.

As a side note, in 2008 my mechanical engineering senior project was to design a regenerative braking system for a bicycle. We all decided that an electric motor and battery was the most efficient/easiest way to go, but that it would be too expensive (exceeding our $100 budget) and didn't pertain to mechanical engineering as much as it does electrical engineering. So the class explored other alternatives, but ultimately we all decided to use elastic energy storage mediums, e.g. winding/stretching springs and bungee cords to slow down a moving bike and convert its kinetic energy into elastic energy. Methods of capture and storage aren't limited to just electrical or elastic energy either, but those two turned out to be the most applicable for a bicycle.

Hybrid cars combine the best of both worlds, longer range with the regenerative braking of an EV, but it leaves the vehicle heavily dependent upon all the disadvantages of an ICE.

Efficiency Losses

You may be surprised to learn that the typical ICE in a consumer car only achieves around 20% thermal efficiency (25% for diesels). This means that out of the total heat capacity of the fuel consumed by the engine, only one fifth of it is actually being converted into rotational kinetic energy (to accelerate your vehicle). The other 3/4th's are going into generating waste heat, noise, and wearing/grinding down metal/rubber/plastic parts.

That small fraction of energy that actually does manage to make it to the output crankshaft then has to overcome additional energy losses:

• Transmission (manual/automatic transmission)
• Drive train (shafts/axles)
• Rolling-resistance (tires and bearings)
• Air resistance (body drag from movement through air)

before actually making the vehicle accelerate forward. The last two are pretty similar for all cars regardless of the motor type, but the first two can be reduced significantly in electric cars. An electric motor only needs a very simple transmission that lets you switch between park, drive, neutral, and reverse. In other words, there are very few mechanical aspects (moving parts, gears, etc) in the transmission, and it's mostly an electrical engineering concern which reduces the weight and increases the reliability significantly. The fewer moving parts, the better.

Secondly, axles spanning across the vehicle body can be removed entirely if individual motors are placed directly at each wheel. This gives superb computer assisted traction control capabilities and removes some of the losses incurred by shaft bearings and differentials, decreases the rotational inertia of the axles, and decreases the overall weight (linear inertia) of the car. Less inertia means more acceleration and less rolling resistance.

Electric vs. combustion motors

"Silence is the sound of efficiency" -Me, circa 2010 (annoyed anytime a loud muffler motorcycle/car passed by me).

An electric motor produces a maximum torque at 0 rpm (revolutions per minute) and diminishes gradually at higher rpm, whereas the torque curve of an ICE is a rather complex curve depending on many factors (timings, fuel ratios, spray configurations, turbulent airflow, boost, compression ratios, just to name a few).

Example curves for a typical ICE

Additionally, an ICE needs a starter (and battery) to bring it above the self-sustaining idle rpm and must be disengaged from the wheels while continuing to consume fuel while idling to prevent stalling. Furthermore, a clutch and transmission must also slowly apply the vehicle's load onto the engine to keep it from stalling and requires the use of gear ratios to keep the wheel rpm in the operating range of the engine rpm (1000-8000 typically).

An electric motor has neither of these issues, as it doesn't need to startup, idle, or consume any energy when stopped, and can apply a massive peak torque from a standstill nearly instantaneously (though software controllers usually apply a smooth ramp-up function to act as a "digital clutch"). In an optimal configuration, the torque would theoretically decay inversely proportionally to its rpm so as to maintain a constant flat power curve, but in reality for a DC motor it's closer to an inverse linear curve with a max power somewhere around half of its max rpm.

1999 Center for Innovation in Product Development

I haven't tried this yet myself, but an electric motor theoretically performs practically identically in forward or reverse rotation, which is why a Nissan Leaf set a record time averaging 55mph entirely in reverse on racetrack!

EV's are very self-contained closed systems (once charged), meaning that their operation doesn't intake air or produce exhaust pollutants. This means that crowded cities full of EV's would have much cleaner breathable air and be significantly (eerily) quiet. Furthermore, since EV's don't need oxygen, they perform just as well in high elevations or even technically underwater (deep puddles).

Maintenance 

Maybe you've grown accustomed to it, but the maintenance on ICE cars is fairly frequent and costly. If you're like me, then you're tired of buying parts designed to wear out (including brake pads, oil filters, drive belts, air filters, spark plugs, etc.). Oil changes may be one of the most frequent and annoying aspects of owning an ICE Vehicle (ICEV). The oil must be exchanged every 5k-10k miles, and even if you drive infrequently (like I did) then you still have to change the oil every 6-8 months because it degrades over time.

Friction brake pads are another important topic because they're consumed much more slowly in vehicles equipped with regenerative braking. Traditional friction brakes are only used to supplement the regenerative braking when the generator and/or battery are unable to absorb rapid incoming energy coming from the wheels during hard-braking. The common ground vehicle has been wasting useful energy by heating and grinding metal pads into dust... for over a century... this has been the predominant method of slowing down cars without recapturing any of that motion (kinetic energy).

Fuel

I've also become weary of purchasing gasoline knowing the harm the oil procurement, extraction, and emissions has on societal conflicts and the environment respectively. EV's obviously still have impacts on the environment, but relatively much less so than ICE vehicles. No one should be expecting EV's to be a perfect solution to all environmental problems, but it's a big leap in the right direction. For one, electrifying ground transportation and its infrastructure prepares us for newly incoming renewable energy sources. Wind, solar, and nuclear energy will directly power our cars in the near future. Here in France, 75%+ of electricity is from nuclear, so I guess you could say that my car runs on nuclear power 😎. In Europe, gasoline costs between 2-3 times as much as in the USA, which provided more than enough incentive for me (and many others) to switch to an EV. But for now the focus has predominately been on marketing luxury/performance EV's because they're already far superior to similar ICEV's in almost every aspect.

Let's also take a moment to recognize that mankind is on track to deplete Earth's oil reserves in just another 50 years (about a total of two centuries), but that crude oil required tens of millions of years to form underground. In other words, we're consuming it at a rate about 100,000 times faster than it's forming... a very unsustainable and irresponsible behavior. The coming paradigm shift will be to embrace distributed energy sources that capture "directly" from the sun, like wind, solar, and hydroelectric. I say "direct" because wind is a consequence of temperature and pressure differences in the atmosphere caused by scattered sunlight patterns, precipitation (for hydroelectric power) is caused by evaporation from the sun, and solar power absorbs photons/radiation directly from the sun. These are all great, but have extra challenges because they are erratically dispersed with some unpredictability in smaller concentrations. However, the "fuel" is freely available as long as the sun keeps burning. Switching away from centralized power generation (coal, oil, nuclear) to a distributed network poses some infrastructure challenges with power transmission and storage, but in the 21st century, there's no question about whether we have the ability to do it, we obviously can 😅. If fusion energy makes some breakthroughs then it would allow centralized power to remain a dominant infrastructure architecture for the foreseeable future.

It's important to note that gasoline can also be used to generate electricity, at a much higher efficiency than small ICE's are capable of in a typical car. By scaling up the design and using a gas turbine, the fuel can be converted into electricity at a rate closer to 60% efficiency! This means that even if we still used gasoline to generate electricity at a centralized plant to charge electric vehicles, we'd be 30% better off overall.

Power vs. Energy

If you're familiar with physics/engineering you can skip this section, but before I go any further I want to clear-up the common confusion around the two distinct units of energy and power. A Joule is a common unit used to describe any type of energy (or work), whether it's kinetic, electrical, thermal, gravitational, elastic, chemical, etc. It's what you could store in a "battery" for later use. Power is a rate of energy, typically measured in Joules per second (also commonly known as a Watt), and is used to describe how quickly energy is being consumed/produced (that is to say, a transfer rate between energy types). If my battery stores 500 Joules, then it could power a 100W light bulb for 5 seconds. As you probably gathered from this example, a Joule is a very small amount of energy. Household items usually range between a few hundred Watts up to a few kiloWatts (kW). For example, microwaves increase the thermal energy content of your food at a rate of about 1kW (1000W). A typical household wall outlet can supply up to a maximum of around 3kW of power.

You may be familiar with the archaic unit known as "horespower", well that's just 0.75kW (=746Watts), they're both units of power. ICE power is traditionally measured in horsepower (USA) or kW (the rest of the world). I'll just stick to kW for now because it makes EV charging much easier to explain/calculate.

Returning to energy, you may have wondered, "what the heck is a kWh?" You've probably seen it on your electricity bills, but the name "kiloWatt-hour" is confusing because it multiplies a rate by a time, which cancels-out leaving just a unit of energy. Basically a kWh is the amount of energy resulting from 1kW of power transfer for 1 hour of time, or 3.6 MJ (3,600,000 Joules). It's pretty amazing that it only costs a dime or two for that much energy.

Vehicle Candidates

I kept my VW GTI running happily for 15 years until I sold it after moving to Europe, then I relied on public transportation for 2 years (luckily this is a viable option in big European cities like Paris) before beginning my search for a practical daily commuter EV. I've listed below the options I was aware of at the time:

• Tesla Model S ($60k-90k)
• Tesla Model 3 ($40k-60k)
• BMW i3 ($45k+)
• Nissan Leaf ($30k)
• Renault Zoe ($20k with battery rental)

The one vehicle that stood-out uniquely was the Renault Zoe, and because of the price, it was the only one I ever seriously considered; and it's not even available in the USA! The Zoe provided the option to rent the battery (that's partly why it's significantly cheaper). I'll explain more details on that later.

The battery rental cost is similar (or less than) what you'd expect to put into the maintenance of an ICEV, but spread out evenly at regular predictable intervals with far fewer unexpected maintenance issues. And I'm guessing that in 5-10 years when I receive a new battery, it will be a newer model with a larger capacity and possibly a faster charging/rate, so my range will be upgraded, either that or the monthly price will decrease. The French government is still giving a €6k Euro stipend right off the price of the car at the dealership to encourage people to purchase EV's.

Charging locations

If you own/rent a home with a garage/carport, you really don't have to worry about anything. You can conveniently charge your car overnight once per week. Otherwise, I highly recommend the chargemap free app/website to find information about charging locations, connectors, speeds, and prices, mostly via community-driven data. You can optionally buy a Chargemap pass ($20) and use it on many participating charging stations, I'd estimate that about half of the charging stations are compatible with it. The goal is to help unify the many diverse charging companies and let you pay a flat rate with just one card. As it stands now, there are many small competitors each with their own small territories (about 10km radius). I guess that's OK if you never travel too far from home, but long roadtrips require planning in advance all the places you will charge, and even prepare some alternate backups. This can be a little tedious the first time around, but repeating trips is much easier later. You'll learn to trust some stations more than others. All of this should get better in the future too, and I recommend planning your roadtrips along free charging stations. Some supermarkets (Lidl, E.Leclerc, IKEA, etc.) offer free charging (may require free membership), but there as much incentive to keep free charging stations well-maintained, so they're not as reliable as the ones you pay for. Again, Chargemap's community is usually pretty good at warning you when stations are out-of-service.

European reader: Renault discontinued their Z.E. Pass partnership, but you can still buy the KiWhi Pass individually, and it offers amazing membership rates allowing customers to recharge at participating stations at a massive discount. I chose the COMFORT plan which costs only €24/year and just 35 cents per charge! It's practically free.

Charging Connector Types

This part is unnecessarily confusing. From what I understand, there are many types of connectors/plugs, but with 3 main types:

• Type 2 (Europe/USA car manufacturers)
• CHAdeMO (Japanese car manufacturers)
• Tesla (Tesla only)

Some of these are obsolete

A Tesla car with support for Tesla's charger AND the type 2 port

Type 2 seems the most promising to me. Tesla is even now providing dual connections to include the Type 2 connector (120kW) on newer vehicles for their European market. So it will probably come down to a battle between Western and Eastern manufacturers, and who knows if we'll ever decide on a single universal standard (I sure hope we do). Again, Chargemap is an excellent resource to find out which stations are compatible with your vehicle's port(s).

The following terms are used to describe the charging rates:

• < 7kW "slow"
• 11kW-22kW "fast"
• > 40kW "rapid"

Your car will usually come with an adapter cable so that you can plug into any standard wall outlet and charge at 3kW max.

Renault Zoe

I decided to focus on the Renault Zoe because it seemed like the most practical option in France (and also if you live in Germany or the UK). I liked that the battery rental emulated what we're accustomed to as customers, paying maintenance over the lifetime instead of all upfront. First I looked for used cars, but there were very few to be found. Seems that people are generally very happy with them. I've heard it's difficult to find a used Tesla too, and EV's depreciate in value slower than ICEV's because they're more reliable. Tesla provides an (8 year) infinite mile warranty to reflect that! See the section below about battery warranties that blow ICEV's out of the water.

With a Zoe I'd be able to:

• Commute (40km per day) to work only needing to charge once per week.
• Never need oil changes again.
• Easily make trips up to 230km away.
• Make practical trips up to 500km in a single day stopping once to fully recharge.
• Free parking in Paris (while Autolib is transitioning).
• "My Z.E." perks.

The online "My ZE" account lets you remotely view the status of your car battery level, schedule charging times, pre air-condition the cabin, etc.

So I finally made the leap and purchased a new 2018 Renault Zoe R90 Intens in September. The "90" stands for the motor's horsepower rating (90hp = 65kW), and the "R" means it's the slower charging model (22kW). The high-end "Q" model can charge twice as fast (43kW), and there's also a 110hp motor version, but both of those upgrades cost extra. Other special features (paint job, rims, upholstery, rear-view camera, automatic headlights/wipers, GPS, etc.) all cost extra too. The "Intens" version I bought included almost all of those features.

The Zoe's power system includes a traditional 12V lead-acid car battery for emergencies to power the computer/lights in case the main drive battery fails or fully drains. I suspect other brands may use similar setups because it's so similar to the electrical system of ICEV's. From what I could gather, the Zoe always keeps the backup 12V battery fully-charged, and it means that you can easily jump-start a dead ICEV with regular jumper cables. I know because I tried it successfully and didn't even need to have my EV powered "on."

The Driving Experience

Once you test drive an electric car, you might fall in in love immediately like I did. The quiet uninterrupted smooth torque is remarkable. The only sound is the wind outside. The only vibration comes from the tires on the road. Driving down a curvy highway feels like gliding through the air. You'll soon wonder how you tolerated an ICEV for so long.

Battery Rental

Customers can choose to buy the main drive battery upfront for an extra €9k or they could pay a monthly fee and when the battery decays below 75% of its original full capacity, it is replaced for free. This contract transfers to the new owner if you sell the vehicle. Depending on the annual driving distances, the battery rental price varies between €69-€239 per month, but they offer an unlimited distance plan for €119/month, so I'm not sure why anyone would ever pay more than that. I chose the 12,500km per year plan for €89/month, which is about what I'm saving in gasoline for the same distance.

Warranty, reliability, and Maintenance

If the maintenance is truly significantly less than an ICEV, I should be saving lots of money in the long term. The Zoe is at most €4k more expensive than a similar ICEV counterpart, so the return on investment should take only a few years. In fact, if you choose to buy the 40ZE battery upfront instead of renting it, Renault guarantees that it will sustain 66% of its initial capacity for up to 8 years or 160,000km (100,000 miles).

Competitors

A Tesla can charge at an impressive 120kW rate and their batteries store around 100kWh. Remarkably, Audi is planning to release the E-Tron that can charge at 150kW and Porsche the Taycan at 350kW! That is insane, but I wouldn't expect that to be affordable for most mainstream consumer vehicles for another 10-15 years.

Perspective

Based on my driving habits, I'm saving about €1,000 ($1,200) annually on gasoline, and am spending only about $1 per full charge with the membership, about $50 annually. The price of electricity in Europe is similar to the US, between 15-20 cents per kWh, so charging my Zoe from home would cost:

0.15 [€/kWh] * 40 kWh = €6

and scheduling the car to only charge during off-peak hours could save $1-2 per charge if you have one of those power plans. However, it's usually even cheaper than that if you charge at a station or have a membership. Not only is it faster than a standard home wall outlet (most non-Tesla stations currently range between 7kW-60kW) but you'll pay closer to:

€1 / 40 [kWh] = 0.03 [€/kWh]

3 cents/kWh. At least for now while the government is providing incentives with subsidies. And don't forget that many FREE charging stations still exist. My car can only charge at a rate up to 22kW, which means it takes about 2 hours to fill up all 41kWh from empty:

41 [kWh] / 22 [kW]  = 1.86 [h]

But in practice there are some energy losses incurred by the battery charging and seems to require around 15% longer in my experience. I typically charge my Zoe from 20 → 90% in 90 minutes. If the car battery is in below freezing temperatures, it could be an additional 5-10% slower. This is another perk for homeowners who have the option of charging their car in a warm garage.

Just to give some more perspective on energy and power magnitudes, if my car was capable of absorbing all the power coming from a (moderately large) 1MW wind turbine, it would take about 2 minutes to fully charge my car's battery (41kWh), and allow me to drive 320km +/- 50km.

41 [kWh] * 3600 [s/h] / 1000 [kW/MW] = 147 [s]

After driving an EV for a few months, ICEV's now resemble glorified model-T Fords from the 1920's with their loud, smelly, greasy, and less reliable design. Once you go EV, you'll never go ICEV again.