Published on January 13th, 2019 | by Andy Miles0
RU An EV Noob? Part 2, The Differences Between Electric Vehicles & Conventional Vehicles
January 13th, 2019 by Andy Miles
I thought it would be a good idea to write some articles to give good advice and information for new and prospective drivers of electric vehicles, to smooth the way for them in understanding electric vehicles. In November, I wrote the first in the series, “RU an EV Noob? Part 1.” That first article attempted to answer the question, “Why buy an electric vehicle?” I aimed to help people understand why electric vehicles are better. This month I continue with the second article, “What are the differences between an electric vehicle and a conventional vehicle?” Here I aim to go into more depth to help people understand exactly what to expect when they go electric, and how to get the best out of an electric vehicle.
Never Seen an Electric Car?
In many respects, an electric vehicle is very similar to any other modern car on the road today. I have heard people say, “I have never seen an electric car,” but in all probability many electric vehicles have passed them by unnoticed. Externally, the only notable differences are the lack of any large air intake at the front, and the lack of an exhaust pipe belching out pollution at the back. Electric cars do not look like glorified golf carts or something out of a science fiction film, but look just like any ordinary car.
We do not need to mention that the car has no engine, or gearbox, and no fuel tank to fill. We can be pleased about the loss of these, as they all have the potential to cost us a lot of money. The car just has a battery, an electric motor, and systems for controlling the motor and charging the battery. It is a much more simple arrangement, and the differences all arise out of that fact.
It’s Bigger on the Inside
One thing a lot of people notice is the TARDIS effect. An electric vehicle is bigger on the inside than would appear possible from the outside. In an electric vehicle, the battery is normally mounted underneath the floor. Imagine a giant smartphone battery sitting under the floor between the four wheels. The electric motor could be at the front or back, or both, but in either case, takes up less space than a large engine and gearbox. This means much more legroom for the driver and passenger, and the inside seems much more roomy than one might expect.
Another effect of the battery mounted under the floor and the positioning of the motors at or above the height of the axles is a very low center of gravity and even weight distribution. With a front mounted engine and gearbox, most of the weight is towards the two front wheels. Fast cornering tends to make the front wheels lose stability, and drift out from the turn. In a Formula One race car, the engine is mounted behind the driver and in front of the back wheels, so that the weight is more evenly distributed, with a slight bias towards the rear, which makes the car more stable when cornering. A properly designed electric vehicle has equally good stability.
Regeneration – Theory
So there we have two differences without any great technological innovation or special equipment, just by replacing the engine and gearbox with the motor and battery, and positioning them in an intelligent way. One great technical innovation in electric vehicles is what we call regenerative braking. This makes driving an electric vehicle entirely different from driving a conventional car.
Without going into all the technical details, let us just say that, obviously, it takes work to generate electricity. If we connect bicycle pedals to a dynamo, you would find it quite hard work to turn the pedals while the dynamo is generating current. The dynamo works using magnetic fields. If you have ever tried pushing two like magnetic poles together, or pulling two magnets apart, you’ll be familiar with the very strong forces involved. Normally, current is applied to the motor from the battery, so that the motor drives the car. In regenerative braking, the car drives the motor, and acting as a dynamo, it drives current back to the battery. Those magnetic forces in the motor while it acts as a dynamo create quite a strong resistance to the movement of the car. This resistance is what we call regenerative braking. When you use regenerative braking for the first time in your electric vehicle, it feels just like putting the brakes on.
So, what is the advantage of that, you might say. There are two definite advantages.
- In ordinary friction brakes, the energy of the car in forward motion is converted to heat. That energy is just wasted. Also, the brakes wear out fairly quickly, are expensive to replace, and produce particulate pollution in the process. Regenerative braking, therefore, reduces wear on the brakes and particulate pollution.
- Regenerative braking is a very effective and smooth way of reducing the car’s speed, but also returns power to the battery, so extending the battery range. Unlike friction braking, where the energy is just wasted as heat, the energy of the car is converted into something useful.
Regeneration – Practice
That is the theory of regenerative braking, but what of the practice? There is quite a lot you need to know about it in order to get the best out of it.
First, in most electric vehicles, it operates when you take your foot off the accelerator pedal. That makes driving much more simple, and makes braking quicker. However, different electric vehicles add layers of complexity on top of that. Many will also put extra regenerative braking in the very top part of the brake-pedal travel. So, you’ve already started regenerative breaking by taking the foot off the accelerator, but now you can increase the braking power by touching your foot on the brake pedal. Pressing down on the pedal operates the friction brakes as normal. Some electric vehicles will have buttons to change to different driving modes, each of which has different characteristics of regenerative braking. Some have paddles on the steering column to control the level of regeneration. Some, like the new Nissan LEAF, put all of the braking on the accelerator pedal, so that taking the foot of the accelerator will progressively slow the car to a halt, automatically applying the friction brakes towards the end. All electric vehicles are different, so you need to learn about regenerative braking in the particular car when selecting an electric vehicle or beginning to drive the one you’ve selected. Once you know about it, it makes driving so much easier and efficient. It is one big difference in electric driving, and a real bonus point.
A Glass Half Empty
So now that I have you all enthusiastic about regenerative braking, you might hear, sooner or later, people saying something against it. As it is something worth understanding, I will mention it. We all know there are people who see a glass as half full, and those who see the same glass as half empty. It costs you a certain amount of battery capacity to accelerate up to speed, and then, when you slow down again, regenerative braking can put around 60% of that capacity back into the battery. That’s a whole lot better than friction brakes that just waste all that energy as heat, but the glass-half-empty people will say, “yes but you still lose 40% in regenerative braking.” Well OK, they have a point, but how can you slow down without regenerative braking? So let’s realize that these people are trying to get the absolute maximum range out of their battery, so instead of being thrilled at getting 60% back, they are really annoyed with losing that precious 40%. They are going to extremes, and not just driving normally. They are looking well ahead, and slow down just by reducing the power down to zero, and without any brakes of any kind — just letting the air resistance and rolling resistance, and perhaps going uphill — naturally slow the car down. That resistance that slowed you down would be there whether you chose to slow down or not, so nothing extra is lost. This is what electric vehicle drivers call “coasting.” I have never bothered with it myself, but am glad to know about it in case I ever need to get to a charging station further away than I can reach comfortably on the remaining battery capacity.
Looking for Electrons
That brings us nicely to another difference – range and journey planning. Unlike fossil-fueled cars, electric vehicles are not so well supported by refueling infrastructure. This is not at all important for local driving, as most drivers will charge their vehicles at home. They only need to consider charging up anywhere else for round-trips greater than the range of the particular electric vehicle. Where the destination is well within the range of the vehicle, the ideal would be to find a charger at the destination. While doing whatever a person came to that destination for, the vehicle is charging up ready for the return journey. The destination might be the place of work, a supermarket parking area, or just a public parking area in the town.
For longer journeys, however, well in excess of the range of the vehicle, it is necessary to identify places to charge on the route and have everything well planned before setting out. When charging en route, a driver does not necessarily want to stop for any lengthy period, as would be the case for destination charging. When stopping for charging en route on a long journey, the charging time needs to be reasonably quick. The new generation of electric vehicles tend to have a range of 150 miles or more, and the majority of people are quite content to stop for a rest after around 100 miles of driving. When they do stop, the majority of people like to stop for between 15 and 30 minutes. The ideal pattern for charging vehicles on long journeys is for any charging stops to be at around the distance a driver would want to stop in any case, and for the time to charge up to be no more than between the 15 or 30 minutes a driver would normally stop for. Vehicles with a range of 150 miles or more, which charge up in under 30 mins, meet this ideal very well for most people. You would need to consider your own driving patterns when specifying a minimum acceptable range for your electric car.
Oasis in the Desert
However, that ideal being met does not depend only on the car, but also the availability of suitable charging infrastructure. In most of Europe, charging stations are positioned fairly frequently on main routes, so that long-distance driving is perfectly possible. In the USA, the government has not taken the initiative in the planning and specifications of charging stations on major routes. Some parts of the USA are not well developed, so that some roads can continue for 100 miles through an empty landscape. When thinking about buying an electric car, you need to be aware of the availability of charging stations in the country that you will be driving in. A car with a range of 150 miles is perfectly adequate where charging stations are sited every 30 miles along the road, as in the UK, but obviously would be impractical if places to charge were 150 miles or more apart.
Take Charging to a Different Level
As a driver of an electric car, you also need to be fully familiar with the different types of charger, and the different rates of charging. There are currently three defined levels of charging, referred to as level-1, Level-2 and level-3.
Level 1 Charging
Most homes have one or more electric sockets outside or in the garage to power outdoor appliances. Level 1 charging uses an ordinary plug in an ordinary outdoor socket. Different countries have different standards for power sockets. In the UK, for example, all power sockets are supplied with 240 V AC current at a maximum of 13 A. in the USA, power sockets can either be 110 V or 240 V for lower and higher power applications. Level 1 chargers have an in-line control box, generally delivering 10 A of power to a Menneks socket plugged into the electric vehicle. A power of 10 A at 240 V is 2.4 kW, so a 24 kWh battery would take 10 hours to charge from flat. That is a relatively slow rate of charge, but is perfectly adequate for overnight charging. If a vehicle that required 10 hours of charging were to be plugged in at eight o’clock in the evening, it would be fully charged by six o’clock the next morning. The Level 1 charger is something useful to carry on the vehicle for emergencies, as it can be plugged in anywhere that has an ordinary outdoor socket. I would advise people to have Level 2 charging at home, if possible, because it is faster.
Level 2 Charging
One thing you might have thought about already is that the electric vehicle runs on DC current from the battery, and the battery requires DC current to charge it up. The AC current supplied in Level 1 charging needs to be converted to DC by a system in the electric vehicle. Some electric vehicles have a maximum capacity in that converter of only 3.3 kW, where others have 6.6 kW. In Level 1 charging, where the maximum power is 2.4 kW, that is not relevant. Level 2 charging is meant to take full advantage of the maximum power capacity of the converter. Level 2 charging requires a dedicated 240 V power line with a capacity of 32 A to comfortably supply the 6.6 kW in the charging system of the electric vehicle.
Level 2 chargers are supplied as either tethered or untethered. Tethered means that the control unit on the wall outside has its own dedicated output cable and special Menneks plug for the charge port of the vehicle. An untethered system has a female Menneks socket on the control box, and requires a connector cable fitted with a male Menneks plug at each end. Tethered systems are more expensive to buy, are in some ways more convenient to use, but have the inconvenience of a long permanently attached cable to be stowed away after each use. Most drivers will carry a charging cable in their electric vehicle for use on public Level 2 chargers, so it may as well be used for home charging too, using an untethered system. It is well worth having a Level 2 charger at home. Supplying a full 6.6 kW, it would take only 3.64 hours to charge up a 24 kWh battery from flat. If your electric vehicle system has a maximum 3.3 kW capacity, it would take 7.28 hours to charge up a 24 kWh battery, which is not much better than the 10 hours for a Level 1 charger.
Level 3 Charging
A charge rate of 3½ hours for a 24 kWh battery is very conveniently fast for charging at home or at a destination, but it would be painfully slow for roadside charging on a longer journey. Level 3 chargers come to the rescue of the weary traveler. A Level 3 charger will typically provide up to 50 kw of power, and could charge a 24 kWh battery in less than 30 minutes from completely flat. People generally charge up with 10 to 20% of capacity remaining and do not charge up to 100%, but stop at around 80 to 85%. That is because the charge rate gets slower as the battery fills up. Think of it like filling up a tank from a pipe attached to the bottom. As the tank fills up, the pressure begins to build up at the filler pipe, so the flow of water gets slower and slower as the back pressure in the filler pipe gets closer to the pressure in the supply pipe. It gets a lot slower after 85%, which is why most people stop there.
As has already been mentioned, electric vehicles have a system on board to convert AC current to the DC current required by the battery. In most vehicles this is either 3.3 kW or 6.6 kW. To provide up to 50 kW of power requires that it is already DC current going directly to the battery. A 50 kW DC power supply is a potentially dangerous level of electrical power. It could never be a matter of just connecting a two-pin plug to the car. The connector will have the two DC current load-bearing pins, but also a number of low powered connectors for safety monitoring purposes. The system is designed so that no current flows to the vehicle until it is properly and safely connected, so no current can flow from the connector before it is plugged in. Before providing current to the vehicle, the system will gain information through the diagnostic connectors about the voltage and state of charge of the battery, and the maximum amount of current which can safely be supplied to it.
The language has changed while I have been involved with electric cars, the word “fast” tends now to be replaced with “rapid” in Level 3 charging. Just to confuse things, Level 2 charging is sometimes now referred to as “fast” charging.
Just to make things more complicated, there are 4 different kinds of Level 3 charging connector. It is important to know about these before buying or using an electric vehicle.
CHAdeMO is one of the earlier level 3 connection systems, and was developed by a consortium of Japanese auto manufacturers, including Nissan and Mitsubishi. The name is derived from “charge on the move,” pertaining to the concept of being able to fast charge en route. Current versions of CHAdeMO deliver up to 50 kW of power, but the next generation of CHAdeMO will deliver up to 100 kW.
CCS, which stands for “combined charging system,” is a European system. A car equipped with CHAdeMO requires a charging socket on the car specifically for that, and also a Level 2 charging socket. CCS combines the Level 2 charging point with two extra pins for the DC power. It uses the control circuits in the Level 2 socket, so doing away with the need for separate control circuits and a separate Level 3 socket. The Level 2 component of the socket can be used for plugging in a Level 2 charger, which is why it is called the combined charging system. The European Union has specified that as of November 2018, all public charging stations must have a CCS connector. Other connectors are not prohibited, and neither are they mandatory, but most electric vehicle charging stations have a number of alternative connectors available to suit different vehicles. It seems likely that eventually, CCS will become the standard connector worldwide. Current versions of CCS deliver up to 50 kW of power, but the next generation of CCS will deliver up to 100 kW and more.
New chargers are coming out now which can deliver up to 350 kW of power, but the power actually drawn will always depend on the car’s systems. The car communicates with whatever charger it is plugged into via the control circuits to say what voltage and current it wants.
3) Fast AC
Fast AC is unique to Renault cars. It uses the same kind of connector as Level 2 charging, but charges at around 22 kW to as much as 43 kW. Some Renault Zoe cars do not have any fast charging at all, so that is something to be wary of. The Renault Zoe has either fast AC but a slower home charging rate, or faster home charging rate but no fast AC charging.
4) Tesla Super Charger
Tesla cars use a proprietary supercharger system for charging en route on long journeys. The supercharger will deliver up to 120 kW using a proprietary connector unique to Tesla cars. Only Tesla cars can use Tesla chargers, but Tesla cars can use other chargers using an adapter.
So, when buying an electric vehicle, it would be a good idea to check what kind of connector is most plentiful in your part of the world, and take that into account. If you already own an electric vehicle and are planning to go on a longer journey, you need to ensure that the charging stations you plan to stop at will cater for your particular vehicle.
Another difference you will need to be aware of is non-universal access methods for charging. With an ICE car, you will be used to turning up at any fueling station and being able to access the fuel pumps and pay for your fuel using a credit or debit card, or in some cases perhaps, paying cash at a kiosk at the fueling station. Every driver has access to fuel, provided they have the money to pay for it. This is not the case with most electric vehicle charging stations. To access the charger, you will normally need a special card or smartphone application issued by the charging station provider. This will involve some kind of pre-registration. It is possible to arrive at a charging station and be unable to use it because you do not have the required preregistration and card or smartphone application. This is a real downside for electric vehicle drivers who need to have a suitcase full of access cards to be sure of gaining access to any charger they might need to use.
EU to the Rescue
In the EU, the same directive that requires all public charging stations to have a CCS connector also requires universal access and payment methods for users without having to have a suitcase full of charger cards. No one seems to be taking much notice of the directive at the moment, even though the deadline passed in November 2018 for making universal access available. We can but hope that the situation will become more like visiting a fueling station as time goes on.
Another important difference when it comes to buying an electric vehicle are leased batteries. Very few companies are now doing leased battery schemes, but it is something to be very wary of if you are buying a used vehicle. The Renault Zoe is the electric vehicle most likely to have a leased battery, though some Nissan Leaf cars also have a battery lease. The idea of a battery lease, was, in the early days of electric vehicle adoption, to remove any worries a new car buyer might have about the longevity and reliability of the battery. The battery is generally the most expensive item in the entire car. When the battery is leased, the price of the new car is a lot less, but there is a monthly payment for the battery. If anything does go wrong with the battery when leased, it is replaced at the expense of the manufacturer. When the lease period is completed, the car owner has a choice of keeping the battery and paying no further lease payments, or having a new replacement battery. In the early days it was thought that batteries might not last all that long, so the lease scheme had merits. Now that batteries have shown themselves to be more resilient than people expected, most manufacturers are no longer offering vehicles with a leased battery. In the used market, a vehicle with a battery lease still in force is not very attractive for a used car buyer, as they might get their used car much cheaper but will have a hefty monthly payment for the battery. People who buy a new car with a leased battery might have difficulty selling the car in the used car market. In reality, though, that difficulty will probably be passed on to a car dealer when they take the car in part exchange for another new car sold to the previous owner.
Electric Vehicle Bonuses
In some countries and cities, you might find some inducements for electric vehicle drivers, such as state help for buying an electric vehicle, free parking, exemption from congestion, or pollution charges, and freedom to use special lanes normally reserved for buses or other special classes of vehicle. Grants and tax credits are often quite generous, so it is well worth looking into what is available before buying. One small perk that is fairly universal is that chargers will invariably have electric-vehicle-only parking spots for their use. Where everyone else has to drive around looking for a space, yours is right there for your exclusive use (provided another electric vehicle driver has not arrived there first).
An internal combustion engine relies on drawing a combustible mixture into the cylinder when the piston is moving down. Firing that mixture provides the power in the engine. A 4-stroke engine fires only once per cylinder in 2 revolutions, so at 500 rpm, each cylinder is firing only 250 times per minute. The maximum power in that minute is the power available from the fuel-air mixture burnt in those 250 firings. When the engine is spinning at 5000 rpm, each cylinder is firing at 2500 times per minute and is burning 10 times as much fuel with 10 times the amount of power released. It is not really as simple as that, because the amount of fuel and air mixture getting into the engine is controlled and naturally reduces at higher engine revs unless the engine is supercharged. That simplified explanation gives a fair idea of how the engine performs. The internal combustion engine has lower power, and lower torque, at lower engine revolutions. That is why you need a clutch and gearbox to get the car moving.
An electric motor behaves entirely differently. When the electric motor is connected to the power source, it has the full power and torque available as soon as it begins to move. That power and torque does not diminish, and is continuous. No clutch or gearbox is needed. When you press the accelerator pedal to the floor, the electric vehicle will surge forward with maximum acceleration, and will continue accelerating smoothly without interruption from gear changes until it reaches the speed you require or the software-limited maximum speed.
As you can imagine, this, coupled with the regenerative braking attached to the accelerator pedal, makes driving an electric vehicle extremely easy and effortless. There is also, even in the tamest of electric vehicles, much higher performance than you might be used to in the average family car. So this provides the final major difference – that an electric vehicle is much more fun to drive.
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