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Electric Vehicle Charging As the number of electric vehicles (EVs) on the roads increases, charging them all becomes a challenge. There are many ways to charge an EV (AC or DC, fast or slow etc), and some charging stations can only charge certain vehicles. This article describes the various charging systems, connectors and varying charge rates, from a few kW up to 1MW! By Dr David Maddison hile there are obviously other difW ferences, the main practical difference between EVs and ICE vehicles is the method of recharging or refuelling. An EV can be charged at home, at work or via a dedicated charging station at a shopping centre, parking lot or other location. In contrast, an ICE or hybrid vehicle is refuelled at a service station or from a fuel can. The amount of time these procedures take can vary wildly. An EV can take hours (sometimes more than a day) for a full recharge, although a ‘top up’ at a fast charger can be much quicker, perhaps under half an hour. In contrast, refuelling an ICE vehicle usually takes a couple of minutes. The time to recharge, along with the distance between charging stations, can cause “range anxiety” for EV drivers. Still, petrol and diesel vehicles are not immune from that, especially when away from urban centres in a country as large as Australia! In places such as the USA, Europe and Japan, there is a sufficiently high population density that charging stations are relatively closely spaced, but that is not always the case in Australia. Also, long road trips of up to 1000km or more are rare in places like Europe and Japan. This article covers the practical and technical aspects of charging EVs, such as connector standards, power supply 16 Silicon Chip issues, charging times, the extent of recharging networks, limitations of charging at home and other relevant matters. Charging stations One of the most important aspects of EV ownership is locating charging stations, especially when planning a long trip. Many EV owners also install a home charger, although most can be charged from a regular power point (but that can be slow). The main components of an EV charging station are: • The power source (usually derived from the mains, but possibly solar panels, other batteries or a generator). • The charging cable. • The connector that plugs into the vehicle. As part of all this, there are various charging standards, data protocols and charging protocols, charger power ratings, voltages and currents. Some charging stations have their own cable and connector; others require you to provide a cable with a suitable connector, typically kept in the vehicle. There are also adaptors to convert from one type of connector to another. It would be grand if any EV could rock up to any charging station, plug in and get a charge, but unfortunately, there are too many competing Australia's electronics magazine standards for that always to happen. Now is as good a time as any to bring up that old chestnut from Andrew S. Tanenbaum: “The nice thing about standards is that you have so many to choose from”! EV charging stations in Australia and NZ There is now a reasonable network of EV charging stations in the more populated areas of Australia and NZ, documented at www.plugshare.com Fig.1: an EV charging station in Adelaide. Source: www.wikiwand. com/en/Plug-in_electric_vehicles_in_ Australia (CC BY-SA 2.0). siliconchip.com.au However, for longer-­distance trips, it is still necessary to ensure you have the range to get between charging stations on your proposed route, allowing for any side trips. Also, during peak periods such as school holidays, there can be 90 minutes of delays at some charging locations; for example, see this reporter’s video on what happened in Australia last holiday period at: https://twitter.com/PhilWilliamsABC/ status/1607951693039423490 Some remote charging stations run on diesel fuel or biodiesel (see Fig.2). An experimental 50kW charger was coupled with a diesel/biodiesel-­ powered generator by inventor Jon Edwards, who called it a “ChargePod”. It produces 3.392kWh/litre of diesel. Some trips in the Australian Outback are unsuitable for electric vehicles with present range limitations (such as the nearly 1900km Canning Stock route – https://w.wiki/6RUS). Battery configurations and charging Virtually every EV on the market today uses lithium-ion batteries (with lithium polymer or LiPo being one variant). They typically have large numbers of cells joined in mechanically and electrically complex ways with embedded cooling systems (between cells in the case of Tesla and some other models), along with sensors, fuses etc. We covered lithium-ion battery technology in detail in the August 2017 issue (siliconchip.au/Article/ 10763). To give an idea of the complexity, the Tesla Model Y has 4400 of 2170 size cells, meaning they are 21mm in diameter and 70mm long. There are 17,600 welded connections, four per cell. Tesla is starting to use 4680 cells in Texas-made models, which are 46mm in diameter and 80mm long. Those battery packs only need 830 cells and 1660 welded connections, giving a significant cost saving. The Tesla Model S battery pack (Fig.3) has 6912 18650-size cells arranged as 16 modules, each in the 6S72P configuration (72 paralleled strings of six series cells) and with individual cell voltages from 3.10V at 0% capacity to 4.15V at 100% capacity. Even though an EV may contain siliconchip.com.au What if your battery runs flat? Check your options with your EV supplier or roadside assistance organisation; for example, in NSW and the ACT, the NRMA offers roadside assistance vans to charge flat EVs. Two NRMA vans have been equipped with 4.8kWh lithium-ion battery packs that provide 1km of charge every two minutes (see siliconchip.au/link/abkc). Enough energy is provided to get to the nearest charging station; a ten-minute charge will get you about 5km. A company called RE:START (https://restartev.com/) has investment from the RACV (the Victorian motoring organisation) and produces a fast charging unit which they say will provide 50km of range in 15mins – see Fig.a. Another European solution is a trailer-mounted generator such as the EP Tender (https:// eptender.com/en/product/) shown in Fig.b. You can rent this trailer for longer trips to charge your battery as necessary, even while driving. The same company is developing a batteryFig.a: a roadside only trailer. assistance fastcharging unit produced Some people have also carried generators in by RE:START. Source: their EVs, but you need a large and powerful one https://restartev.com/ to charge at a reasonable rate. A YouTuber permanently installed a generator in his Tesla as an experiment, thus turning it into a hybrid – see Fig.c. The video is titled “Cordless Tesla (I Drive 1800 miles without charging)” and is at https://youtu.be/hHhf223jGIE If all else fails, you would have to either call a tow truck or a nearby friend with a portable generator. Fig.b: a solution to EV range anxiety. Source: https://eptender.com/en/ product/ Fig.c: a rear view of the ‘hybrid Tesla’ with a 10kW generator. Source: youtu. be/hHhf223jGIE Fig.2: a diesel/biodieselpowered EV charger in the Outback. Source: https:// thedriven.io/2018/12/14/ diesel-charge-evs-remotelocations-greener-thanyou-think/ Fig.3: a partially disassembled Tesla Model S battery pack with 6912 18650-size cells in 16 modules. It has a rated capacity of 85kWh at 400V DC. Source: https:// hackaday.com/2014/09/13/ tesla-model-s-batteryteardown/ Australia's electronics magazine July 2023  17 standards from Table 1 and adding those shown in Table 2. Fig.4: the charging scheme for a typical lithium-ion battery, like those used in most EVs. Charging Connector Types EV Charging connectors and protocols can be divided into AC charging (single-phase or three-phase) and DC charging, with preferences for different connector types by region shown in Fig.5. While we’re showing regional preferences, different connector types can still be found within the same region. The following types of connectors are in use or planned: AC ● Type 1 (Yazaki, SAE J1772, single-­ phase) ● Type 2 (Mennekes, SAE J3068, three-phase) ● Type 2 (GB/T, type 2 physical connector with different pinouts) ● Type 3 (Scame, uncommon) thousands of cells, each cell still has to be charged using the basic lithium-ion charging scheme shown in Fig.4. The primary charging scheme involves charging at a constant current until the maximum voltage is reached, then holding them at that voltage until the current drops below a certain level. If the initial state of charge is low, this scheme might also be preceded by a ‘conditioning charge’ at a much lower current, to allow the cell chemistry to stabilise before rapid charging begins. Regardless, the variation in charge voltage and current will be managed by the battery management system (BMS). Individual lithium cells might range in voltage from 3.10V to 4.15V in the case of the Model S, but due to the 6S configuration, each module charges to 24.9V. The modules are also arranged in series sets of 16, giving 398.4V (24.9V × 16), so the vehicle requires a 400V charger. There is no chance of connector incompatibility due to different connector standards if the EV owner uses their own cable, as long as the remote end is compatible with the charging station connector. However, at high-power DC charging stations, the cable is permanently attached to the charger because it is thick, heavy and often has coolant running through it. In Australia, the Type 2 connector (also used throughout Europe) is the most common to find. This can be used for AC or DC charging. We will come back to that a bit later. Charging stations and cables Table 1 – SAE J1772 voltage & power standards (limits) for North America Charging stations are either AC or DC. If the charging station supplies DC, it is applied directly to the battery pack, and the charge rate is limited only by what the pack can handle. However, if the station supplies AC, the vehicle uses an onboard AC-to-DC converter, which will typically be the limitation on the rate of charge. For example, many plug-in hybrids have an onboard converter that’s limited to 7.2kW (32A <at> 225V AC single-phase), while some EVs are limited to 11kW (16A <at> 432V AC three-phase); others can handle 22kW (32A three-phase). At lower-power AC charging stations, the EV owner can use their own cable, which is kept with the vehicle and plugged into the charging station outlet (or a cable might be provided). 18 Silicon Chip Voltage and power standards Various EV charger power and voltage ratings have been defined. Table 1 summarises those for North America. The IEC (International Electrotechnical Commission) has produced standards for international implementation by adopting most of the SAE Method Current DC ● CHAdeMO (AA⋆) ● GB/T (BB⋆) ● ChaoJi (planned) ● CCS “Combo” Type 1 (EE⋆) ● CCS “Combo” Type 2 (FF⋆) ● Megawatt Charging System ⋆ AA, BB, EE & FF are designations under the IEC 62196 standard. AC & DC ● NACS (Tesla) Combined Charging System Combined Charging System (CCS) connectors are based on extensions to the Type 1 (North America & Japan) and Type 2 (Europe & Australia) Voltage Power Notes AC Level 1 16A 120V 1.92kW Standard domestic outlet AC Level 2 80A 208-240V 19.2kW 240V single-phase or 208V three-phase DC Level 1 80A 50-1000V 80kW DC Level 2 400A 50-1000V 400kW Table 2 – IEC additional charging standards (limits) Mode Type Current Voltage Power 250V 4kW 16A 480V 11kW 2 single-phase 32A 250V 7.4kW 32A 480V 22kW 3 single-phase 63A 250V 14.5kW 63A 480V 43.5kW 200A 400V 80kW 1 single-phase 16A three-phase three-phase three-phase 4 DC Australia's electronics magazine The three-phase power ratings are about 50% higher than the product of the voltage and current, since the current rating is per conductor and there are three conductors rather than two for singlephase. siliconchip.com.au Fig.5 (left): some common EV charge connector types. Not shown are Type 3, ChaoJi or Tesla. For more details, visit https://w.wiki/6RUd Fig.6 (below): the Type 1 connector pinout. L1 is AC Line 1, N is Neutral for Level 1 charging or AC Line 2 for level 2 charging, PE is protective earth, PP is the ‘plug present’ signal and CP is ‘control pilot’ for various control signals. Source: https://w.wiki/6RHE (CC BY-SA 4.0). L1 N PP CP PE Fig.7 (right): a Type 1 connector. Source: https://w. wiki/6RHF connectors. The extensions consist of two additional DC connector pins to allow high-power DC charging. In such a configuration, the AC pins of the original part of the Type 1 and Type 2 connectors are no longer used. The extended connector is called CCS Type 1 (CCS1), Type 2 (CCS2), Combo 1 or Combo 2. Power can be delivered at up to 350kW and 200920V. We will illustrate these connectors later. Type 1 and Combo 1 The Type 1 connector is also known as the SAE J1772, J plug or Yazaki (see Figs.6 & 7). It is also covered by the international standard IEC 62196 as the Type 1. It is common in Japan & North America, and is used in Australia on cars such as the Holden Volt, Nissan Leaf, Mitsubishi Outlander PHEV, BMW i3, BMW i8 and Porsche Taycan. The Combo 1 connector for highpower DC charging is a Type 1 with two DC charging pins added (see Fig.8); the AC pins are not used. Type 2 and Combo 2 Type 3 Also known as Mennekes or IEC 62196-2, Type 2 is a mandated standard in Europe and commonly used in Australia, mainly by Teslas and some European models. These are installed at Tesla charging stations, although only Teslas can connect at such stations. For AC charging, vehicles with this connector typically charge at 7.2kW for 230V/32A single-phase AC or 22kW for 400V three-phase AC. Two more DC charging pins are added for high-power DC charging, forming the Combo 2 or CCS2 F CP N DC+ Fig.8: a Combo 1 plug for high-power DC charging. Source: https://w. wiki/6RHG (CC BY-SA 4.0). siliconchip.com.au The Type 3 or Scame connector was used in France and Italy but has now been superseded by the European standard connector, Type 2. GB/T The Chinese GB/T 20234.2-2015 connector uses the same physical connector as Type 2 (AC) but with gender differences for the plugs and a different signalling protocol. GB/T (DC) The GB/T DC charging connector is mainly used in China (see Fig.11) M PP PE L3 connector (Figs.9 & 10), which can transfer power at 350kW. The AC pins are eliminated or not used. Where this connector is used in the USA, it is covered by the SAE J3068 standard. PP L1 L2 DC- L1 CP PE L2 DC- N L3 DC+ Figs.9 & 10: a Combo 2 connector (the leftmost cable in Fig.10); yellow AC pins are unused. Without the bottom two pins, it would be a Type 2 (the rightmost cable in Fig.10). F is the charging station outlet, while M is the car inlet. PP is the ‘proximity pilot’ signal, CP is the ‘control pilot’ signal, PE protective earth, N neutral and L1-L3 are the three phases. DC+ and DC- are only used for Combo 2 charging. Source: https://w.wiki/6RHJ & https://w.wiki/6RHK (CC BY-SA 4.0). Australia's electronics magazine July 2023  19 S+ CC2 S- CC1 DC+ A+ DCPE A- Fig.11: the GB/T DC connector. S+ & S- are CAN bus, CC1 & CC2 the charging confirmation signals, A+ & A- are auxiliary power, PE is protective earth and DC+ & DCcarry up to 1kV at 250A. Source: https://w.wiki/6RHM FG SS1 N/C DCP DC+ DCPP C-H C-L SS2 Fig.12: the CHAdeMO connector pinout. FG is ground, N/C is not connected, DCP charging enable, SS1 & SS2 are the charging start and stop signals, PP is the charge interlock to disable the drivetrain during charging, while C-L & C-H are CAN bus signals to communicate with the vehicle. Source: https://w.wiki/6RHL and is also designated as the BB configuration under IEC 61851-23, IEC 61851-24 and Chinese standard GB/T 20234.3. A power delivery of up to 250kW is possible, and CAN bus signalling is used. CHAdeMO CHAdeMO is a Japanese standard (see Figs.12 & 13). The name comes from “Charge de Move” (a French phrase), which its developers interpret as “charge for moving”. However, it originally comes as a pun on the phrase “o cha demo ikaga desuka” (おちゃでもいかがです か), which means “how about a cup of tea?”, referring to the time taken to charge a vehicle! CHAdeMO is popular in Japan but less widely used in the USA or Europe. The second generation CHAdeMO standard is capable of 400kW <at> 1kV/400A DC. In Australia, the CHAdeMO connector is used by the Nissan Leaf; as more EVs are bought to Australia, it might become more widely adopted. Tritium-brand charging stations support this connector. The connector supports bidirectional operation, such as using the EV as a power source (more on that later). A third generation, called ChaoJi, that can deliver 900kW is being co-­ developed with China; see https://w. wiki/6RHf ChaoJi Not to be confused with the Tesla Megacharger, the MCS (Fig.14) is a high-power charging connector under development for large EVs (eg, trucks, ferries and aircraft). It has a power rating of 3.75MW or 3000A at 1.25kV DC. 20 Silicon Chip Charging-related standards such as connectors, protocols and ‘vehicle to grid’ (V2G, described below) are covered by specifications in the following documents: ● China: GB/T 20234 ● International: IEC 61851, IEC 62196, IEC 63110 & ISO 15118 (V2G) ● North America: SAE J1772, SAE J3068, SAE J3105 (heavy vehicles) & SAE J3271 (megawatt charging) Some charging methods and protocols are proprietary and not covered by the above standards. fast DC chargers that form the Tesla Supercharger network and facilitate long-distance trips, usually at 120kW or 250kW. There are also lower-power Tesla ‘destination chargers’ at places like hotels and shopping centres, typically delivering 22kW. Tesla NACS Tesla has developed its own charging standard called the North American Charging Standard. It was initially proprietary, but Tesla has now published it for all to use, and Aptera Motors has adopted it. The connector is smaller than a J1172/CCS connector but uses the same pins. It has the same communications protocol as CCS, ISO 15118 and DIN 70121. In Australia, Tesla uses the Type 2 connector. A Tesla Model 3 has additional pins for higher power charging, with a CCS Type 2 connector, but it can also use a Type 2 connector only. ChaoJi, also known as CHAdeMO 3.0, is a proposed standard for an EV car connector developed between Japan and China for charging at powers up to 900kW DC with a maximum voltage of 1.5kV and a maximum current of 600A. It is designed to be backward-­ Adaptors compatible using an adaptor for Various adaptors (see Fig.15) are CHAdeMO and GB/T DC charging. A available to convert one charging conmegawatt charging connector called nector to another type, but data signals “Ultra-ChaoJi” is also under devel- must also be compatible. opment. Megawatt Charging System (MCS) Fig.13: a CHAdeMO plug. Source: https://w.wiki/6RHQ Charger & connector standards Tesla Supercharger Tesla Superchargers are high-power Australia's electronics magazine Charging levels Depending on the available power, there are different charging levels (not to be confused with connector type), as shown in Tables 1 and 2. The following names are commonly used in Australia. These charging level names do not conform with the IEC international recommended levels (which they call Modes), outlined in Table 2. siliconchip.com.au Fig.14: a prototype Megawatt Charging System connector v3.2. There are two DC pins, four data communications pins (white) and a protective earth pin (PE). Source: https://w.wiki/6RHN (CC BY-SA 4.0). Fig.15: a Type 1 to Type 2 adaptor sold by EVSE. Source: https://evse. com.au/product/type-1-to-type-2-evadapter-cable-32a-2 Level 1 uses a standard domestic single-phase 230V AC ‘GPO’ outlet. This is the most basic level of charging. The charging power is 2.3kW in Australia and NZ. At this rate, it takes one day plus eight and a half hours to fully charge a Tesla Model 3 from flat, with 14km of range added per hour. Single-phase 15A 3.45kW outlets can also be installed in premises in Australia & New Zealand, increasing that rate to 20km/hour and reducing the total charging time for that vehicle to around 22 hours. You will often see slightly higher powers quoted because the supply voltage is usually higher than the nominal voltage of 230V AC; those higher power ratings are generally based on an average of 240V. A proprietary single-­ phase Tesla charging station will deliver 7.2kW, adding 42km per hour of charging and fully charging the Model 3 in 10.5 hours. Level 2 charging is from a threephase (~400V) 16A outlet. Such outlets are not typical in homes in Australia or New Zealand but can be installed easily. The power delivery is 11kW, taking 5.5-7.5 hours to fully charge a Tesla Model 3 at a rate of 65km of range added per hour. Note that 400V 32A outlets are also possible and provide 22kW, doubling that charging rate and halving the total charging time. There is some argument over the exact definition of “Level 3”, but this refers to high-power DC charging, which is unlikely to be affordable and not always possible in domestic installations. The typical power delivery is 120kW, and it takes about half an hour to charge a Tesla Model 3 from flat to 80%. But note that repeated fast charging can prematurely age the battery. siliconchip.com.au Fig.16(a): An overall view of one of the chargers. There is a place to tap a payment card above the car symbol. Local council charging station I had a close look at my local council charging station, which is typical of what might be found around Australia – see Fig.16. Each side of the station has a Type 2 outlet (socket) into which you plug in your cable. The Tesla prime-mover Megacharger Terminology varies from country to country, but the ten-wheel unit that pulls an eight-plus-wheel trailer is called a prime-mover in Australia and New Zealand, or a tractor unit, among other names, in North America. Tesla Fig.16(b): Another charger with its own cables (Type 2 plug & socket); they can be unplugged from the charger socket to plug in your own. In the corner is a close-up of the Type 2 plug. The cost to charge an EV It depends on how much you pay for electricity and how efficient your charger is, but at around 30-40¢/kWh in Australia, assuming 10% losses, charging a typical 60kWh EV battery will cost around $20-26. Public fast chargers have a higher cost per kW (60¢/kWh for some 350kW chargers), so a full charge might cost up to $40. The ‘fuel economy’ of EVs is generally measured in kWh/100km. Some people overseas use “MPGe” or miles per gallon (equivalent). However, equating electricity to a volume of liquid fuel containing a similar amount of energy is flawed logic. At around 17kWh/100km (a figure measured in real-world testing), that $2040 charge will take you around 350km. By comparison, $20-40 will buy you 11-22 litres of petrol which, for a hybrid Camry, equates to a range of about 250-500km. The average fuel consumption of a purely petrol-powered vehicle was 10.8L/100km from the ABS 2020 figures. When charging an EV, you are not paying the 46¢ plus GST per litre “excise” applied to petrol and diesel. However, in Victoria, EVs are taxed at 2.6¢/km and hybrids at 2.1¢/km. The excise money is meant to pay for road building and maintenance, although it is actually a general revenue-raising tax. Australia's electronics magazine July 2023  21 is developing a prime-mover called the Tesla Semi (see Fig.17), not to be confused with the Tesla Cybertruck, a much smaller utility vehicle. The vehicle is said to have a 900kWh, 1000V battery, a range of 997km with no load, and a range of 480km or 800km with an unspecified load, depending on the model. It is to be charged with a 1MW DC charger called the Megacharger. This charger will also be used for the Cybertruck, which employs a 1000V battery system rather than the 400V system used in Tesla cars. Some industry experts are sceptical about the capabilities of the Tesla Semi and its cost-effectiveness. Ultimately, that will be decided by the marketplace. The Semi started deliveries in the USA in December 2022. A car charging cable such as the V3 would not be suitable for charging the Tesla Semi because it would take too long with battery capacities in the hundreds of kWh. Therefore, Tesla developed a V4 charging cable that can deliver 1MW. Like the V3 cable, it has active cooling, but instead of 12 power wires, it has two. Each wire is immersed in its own coolant return tube, with coolant supplied by two tubes along the body of the cable – see Fig.18. According to Tesla, a current density of 35A/mm2 can be achieved. Adding the coolant lines to prevent overheating means less copper is needed for a given current, saving expensive copper and reducing the weight of the cable. By comparison, the Tesla V3 supercharging cable (also shown in Fig.18) has a power conductor current density of about 14A/mm2, allowing up to 250kW to flow. The Tesla V2 cable Can the electrical grid handle mass EV charging? There are already problems in the upmarket suburb of Brighton in Melbourne, where EV-owning residents wanted to set up a charging schedule. See the articles at siliconchip.au/link/abjp (Herald Sun) and siliconchip.au/link/abjq (radio 2GB). We don’t know what future electricity policy will dictate. Still, in Australia, there is the big question of whether enough reliable, low-cost power will be available to charge all the anticipated EVs. Consider that total generation has been stagnant for the last few years. Secondly, what will happen if everyone goes home from work, plugs in the EV and draws an extra 2.3kW to 22kW (Level 1 and Level 2 charging) per vehicle per household, all at the same time? Our back-of-the-envelope calculations suggest that the total generation would likely have to at least double to provide enough power to charge all those vehicles, assuming the demand is evenly spread out. That’s based on electric passenger vehicles only; we haven’t considered delivery trucks, semi-trailers or other commercial vehicles, including those used in mining. The grid will also need significant investment to carry twice as much power, with many transformers needing to be upgraded, along with transmission lines. That makes local generation and storage, such as with PV solar panels and stationary batteries, seem attractive. Unfortunately, there are problems with that too. Each home would need a very large solar system to gather enough energy to charge an EV (depending on how much driving was being done). As it’s unlikely that the charging time would coincide with power availability, large batteries would be needed to store the energy when it is available, then charge the vehicle when it’s plugged in. is uncooled and has a current density of up to 4A/mm2. Electrical power losses in conductors scale with the square of the current, so losses can be reduced by reducing the current and increasing the voltage. To achieve four times the power rating of the V3 cable, the charging voltage has also been increased from 400V for the Tesla Models 3, Y, S and X to 1000V for the Cybertruck and the Semi. Increasing the voltage results in new problems, such as the requirement for more insulation and additional design elements to prevent electrical breakdown and arcing. The above is about the cable only; no details have yet been released on the type of connector used with the 1MW charging system. Wireless car charging The SAE J2954 standard relates to wireless charging or “wireless power transfer (WPT)” for EVs – see Fig.19. Power deliveries of 3.7kW, 7.7kW or 11kW are allowed for. There is also a provision for 500kW transfer for large vehicles under J2954/2. The principle of wireless charging is similar to inductive charging but uses ‘resonant inductive coupling’. Currently, the Genesis GV60 (a Hyundai 1 MW + DC CHARGING IMMERSION COOLING TECHNOLOGY CHARGING AMPACITY 40 HIGH VOLTAGE CONDUCTORS 2 AMPS / MM 35 V3 CHARGING CABLE 30 25 COOLANT TUBES 20 15 HV CONDUCTORS IMMERSED IN COOLANT RETURN TUBES 10 5 V2 Fig.17: a Tesla Semi EV. Source: Tesla. 22 Silicon Chip V3 V4 V4 CHARGING CABLE COOLANT TUBES Fig.18: a comparison of the Tesla V2, V3 and V4 charging cables with crosssections showing the power conductor parts of the V3 & V4 cables. Source: Tesla, screen grab from https://youtu.be/LtOqU2o81iI?t=1600 Australia's electronics magazine siliconchip.com.au luxury brand) is the only EV with wireless charging, and this option is only available in South Korea at the moment. For more details, see the video titled “How to make EVs - From EV Batteries to Wireless Charging Technology | Genesis GV60” at https://youtu.be/ npUNCgT68bE The Open Charge Alliance The Open Charge Alliance (OCA; www.openchargealliance.org) is an international consortium to promote the use of open standards via the adoption of the Open Charge Point Protocol (OCPP) and the Open Smart Charging Protocol (OSCP). These standards are for ‘cloud-based’ charger system (network) management. The OCA standards are for communications between the charge point or charge point network and the ‘back office’ and do not involve physical connector or charging protocol standards for an EV. The EV owner does not interact directly or knowingly with OCPP and OSCP, although they might operate ‘behind the scenes’. OSCP 2.0 (Fig.20) is for charging site owners and electricity utilities. It communicates predictions of locally available electrical production and generation capacity, fits production and generation resources to grid capacity and facilitates communication between the providers. In other words, it helps ensure that sufficient electricity will be available for the vehicles that need charging. OCPP 2.0.1 (Fig.21) is relevant to charging points, providing a consistent experience even when charging at locations owned and operated by different parties. It supports SOAP and JSON data formats, smart charging, load balancing, charging profiles, tracks the time spent charging and the current status while providing device management, transaction handling and security. Fig.19: a wireless charger for an EV, which can surprisingly deliver multiple kilowatts. Usually, a low barrier is placed so that the vehicle naturally comes to a stop over the charger. Source: https://w.wiki/6RHP (CC BY-SA 3.0). Fig.20: the Open Smart Charging Protocol (OSCP) communicates a 24-hour forecast of the available electricity (blue). Based on this, service providers generate charging profiles (red) for EVs to make the best use of the grid capacity. Source: www.openchargealliance.org/protocols/oscp-10/ Vehicle to Grid (V2G) Vehicle to Grid is a concept where an EV acts as an energy reservoir for the grid (https://w.wiki/6RHk). An EV has a convenient large battery, generally much larger than home energy storage batteries, such as: • Tesla Powerwall (13.5kWh; http:// siliconchip.au/link/abk3). • Enphase Energy (10.08kWh for IQ Battery 10; siliconchip.au/link/abjz) siliconchip.com.au Fig.21: the Open Charge Point Protocol (OCPP). EVSE is the Electric Vehicle Supply Equipment, ie, the charging station, while CSMS is the charging system management software. You don’t need to provide payment and charging details separately with every charging station you pull up to, as long as they support OCPP. Source: https://youtu.be/0exHWxV-uW8 Australia's electronics magazine July 2023  23 Fig.22: the Wallbox Quasar offers bidirectional power flow for V2G applications. Fig.23: a Ford F-150 Lightning connected to a home charging station. The vehicle might be charging or operating in either V2G or V2H modes. Source: www.ford. com/trucks/f150/f150-lightning/2022/features/intelligent-backup-power/ • LG Home Battery (16kWh for RESU16H Prime; siliconchip.au/link/ abk2) • sonnenBatterie Evo (10kWh; siliconchip.au/link/abk1) • Redflow ZBM3 (10kWh; http:// siliconchip.au/link/abk5) • DCS PV Series (15kWh; http://­ siliconchip.au/link/abk0) • Zenaji Aeon (1.93kWh, expandable; siliconchip.au/link/abk4) Note that some hybrid vehicles support V2G, but they have much smaller batteries than dedicated EVs, so they will not work as well in this role. The way it works is when an EV is plugged into a home charger, power can flow bidirectionally to either charge the EV battery from the grid or discharge it and export the energy into the home or back into the grid to meet local demand. As with grid-scale batteries, the objective is to charge the battery when power is cheap and use it in the home or export it when power is expensive. Still, you would want to avoid totally discharging it, especially when you might need to use it. Of cars available in Australia, V2G is supported by the Nissan Leaf (full EV, 39kWh), Mitsubishi Outlander PHEV (hybrid, 20kWh) and Mitsubishi Eclipse Cross (hybrid, 13.8kWh). V2G Jetcharge (siliconchip.au/link/ abk6) are doing work in this area in South Australia. The Wallbox Quasar (siliconchip. au/link/abk7), shown in Fig.22, is an example of a bidirectional charger What’s inside a DC fast charger? DC fast chargers are essentially switchmode power supplies converting AC from the mains grid to a variable DC voltage at high power for battery charging. Of course, they incorporate battery charging logic, communications with the vehicle, metering, communications with the owner and everything else required to do the job. All but the most basic fast chargers will incorporate multiple switch-mode units in parallel – see the adjacent photo. For a start, it’s very difficult to design a single device to deliver 100kW or more, while it’s relatively easy to design a supply capable of delivering, say, 10kW that can be paralleled for more power delivery. This also gives manufacturers the flexibility to design one charger board and then deploy it in a range of products, from the low end to the high end. suitable for V2G. It can charge or discharge at up to 7.4kW, operating between 150V and 500V and using a CHAdeMO connector plus internet connectivity. Other carmakers supporting V2G technology include: • Volkswagen Group are building V2G hardware into all their vehicles that use their Second Generation Modular Electric Toolkit (MEB), a standardised EV platform. Vehicles on this platform include various Audi, Seat-Cupra, Skoda and Volkswagen EVs using the Type 2 port. • Porsche (part of VW) has been testing the concept with the Taycan EV; it may be able to be implemented in future with a software update. • The Ford F-150 Lightning pickup truck in the USA supports V2G (see Fig.23), although V2G is currently only being tested: siliconchip.au/link/abk8 Tesla has not announced plans to support V2G, although presumably, they could implement it with a software upgrade in some models. Before using V2G, consider whether it will shorten the expected life of your EV battery and whether the cost of replacing it will be higher than the Fig.25: the Kerb Charge system, charging an EV in the street. Source: www.kerbcharge.com.au The power source for a Tesla V3 Supercharger being installed. Note the two rows of what appear to be metal boxes containing switchmode converters. Source: https:// teslamotorsclub.com/tmc/threads/supercharger-beaverton-or.283907/page-2 24 Silicon Chip Australia's electronics magazine siliconchip.com.au Hybrids vs EVs Fig.24: power outlets on the Ford F-150 Lightning pickup truck. Source: same as Fig.23 benefits of the V2G connection. Vehicle to Load (V2L) and Vehicle to Home (V2H) Vehicle to Load (V2L) refers to the ability to plug mains-powered appliances into your EV, such as power tools, floodlights or a kettle. This is useful for tradesmen working at building sites or recreational campers, for example. With Vehicle to Home (V2H), a vehicle can be plugged into your home via the right sort of charger interface, to power your home during a power outage. A variation of this is Vehicle to Building (V2B), where a vehicle powers an entire building, or V2X, where it powers ‘everything’, with bidirectional power flowing through a building to the grid. V2L is available on EVs such as the Hyundai IONIQ 5 (Fig.26) and KIA EV6. The Ford F-150 Lightning mentioned above also supports Vehicle to Load (V2L) and Vehicle to Home (V2H) during power outages. Battery charging efficiency According to tests by ADAC, a major German car association, electrical EVs are purely electric and only operate from a battery, while hybrids combine an internal combustion engine (ICE) with a battery. In both cases, regenerative braking is used to recover some kinetic energy into the battery during braking. Plug-in hybrids are hybrids where the battery can also be recharged from the mains. One advantage of a hybrid over a regular ICE vehicle is that the engine can mostly run at optimal efficiency, at a fixed RPM and throttle position, to charge the battery and/or drive the wheels. Not all models mentioned below are representative and are not necessarily current or available in Australia or New Zealand. We have included the range for all-electric EVs and plug-in hybrids on battery only. All-Electric: Audi e-tron (336-444km), BMW i4 (510-590km), Hyundai Ioniq electric (373km), Jaguar I-Pace (470km), Kia EV6 (484-528km), Lexus UX300e (305km), Mini Cooper SE (200km), Mercedes-Benz EQA (480km), Nissan Leaf (270-385km), Porsche Taycan (431-484km), Tesla Model 3 (491-614km), Tesla Model S (637-652km), Tesla Model X (580-547km), Volvo XC40 Recharge Pure Electric (380-418km). Parallel Hybrid: the ICE and electric motor are locked together and can drive the vehicle individually or together, eg, Honda Insight. They usually require the ICE to be running to move. Mild Parallel Hybrid: like a parallel hybrid but with only a small electric motor to keep various pumps and the aircon compressors running, and provide extra power for acceleration: Honda Civic Hybrid, Honda Insight 2nd generation, Honda CR-Z, Honda Accord Hybrid, Mercedes Benz S400 BlueHYBRID, BMW 7 Series hybrids, General Motors BAS Hybrids, Suzuki S-Cross, Suzuki Wagon R and Smart Fortwo. Series-Parallel Hybrid: two drive motors are used, ICE and electric. Depending on conditions, either motor can be used or both together, coupled in such a way that each can contribute any amount of the total power, eg, Toyota Hybrid Synergy Drive/Toyota Hybrid System II including: Toyota Prius, Ford Escape and Fusion Hybrid, Lexus RX400h, RX450h, GS450h, LS600h and CT200h. Series Hybrid: driven by an electric motor and can function as an EV when there is sufficient battery power, but an ICE drives a generator to charge the battery: BMW i3 with Range Extender, Fisker Karma, Nissan Note with ePower. Plug-in Hybrid: a serial or parallel hybrid with a larger battery that can act as a pure EV for shorter distances: MG HS Plus EV (52km), Ford Escape ST-Line PHEV (69km), Mitsubishi Outlander PHEV (69km), Mini Countryman All4 Hybrid (61km), Mercedes-Benz GLC 300e (46km), Range Rover Velar (69km), BMW X5 xDrive50e (94-110km), Porsche Panamera (51km). Note that the electric range of plug-in hybrids is limited; it’s 110km at most in those examples and usually much less. Long journeys will still invoke the ICE motor (still, many peoples’ commutes are within these ranges, possibly even the round-trip). Fig.26: an external V2L interface on a Hyundai IONIQ 5. There is also an interior outlet. There is a similar external adaptor for the Kia EV6 as well as an interior outlet. Source: www.hyundai.co.nz/v2l siliconchip.com.au Australia's electronics magazine July 2023  25 Considerations for a home EV charger If you want to buy an EV and charge it at home, here are some things to consider: 01 The standard plug-in charger that comes with your EV will take many hours, maybe days, to fully charge it. You need a dedicated hard-wired highpower charger to charge the car quickly. Still, the slow charger may be adequate if you only drive short distances or will leave it plugged in permanently between trips that do not fully exhaust the battery. 02 Many different chargers are available. Some are ‘smart’, with various features; some support solar panels; some are bidirectional and support V2G (see elsewhere). Choose one that suits your needs. 03 Consider whether you should buy a charger that supports standards from the Open Charge Alliance (www.openchargealliance.org). 04 Unless you are offered an excellent deal, consider whether you need a charger from your vehicle manufacturer that might only charge specific models. Would you be better off with a more generic model that will work on other vehicles in your household (perhaps later purchases) or others you may buy in future? Check that the charger will work with your proposed vehicle and does not affect the vehicle warranty (it shouldn’t). 05 Make sure you get the right cable length to go between the vehicle and the charger. You might usually charge it in a garage, but what if you sometimes want to charge it on the driveway? It might be worth getting a longer cable. 06 If you have multiple vehicles in your household, you might need multiple chargers to charge more than one car simultaneously. Will your household power supply support that? 07 If charging from solar panels, ensure you have enough capacity, especially for winter use. It is unlikely that you will be able to fully charge from solar panels unless you have a very large solar installation and can charge during most of the day. 08 Charging your car might cause you to drain your solar battery. Will the charger communicate with the battery and take power from the grid when necessary? Remember that there are substantial losses in charging from battery to battery. losses of between 10% and 30% occur when charging an EV from a wall socket at home, and losses of 5% to 10% occur when using a ‘wall box’ (dedicated hard-wired charger, presumably Level 2). In their tests, the Renault Zoe lost 30% at the wall socket, while the most efficient car was the Fiat 500e, which lost only 5%. Further losses occur due to some vehicles drawing power from the grid to heat or cool the battery at extreme temperatures. Battery heating and cooling is very important, since many early EVs that lacked active battery temperature management experience shorter battery lives with early reductions in range. Converting battery power back to motive power involves an additional 5% to 10% loss – see siliconchip.au/ link/abk9 Remember that those were only the losses from the wall to the battery and did not include grid losses or the inefficiencies of the power generation itself. More links & videos • A Daily Mail article highlighting the difficulty of finding a charging station that is not busy: siliconchip. au/link/abjs • “Towing with my Ford Lightning EV Pickup was a TOTAL DISASTER!” – youtu.be/3nS0Fdayj8Y • “Can a generator charge your Tesla?” – youtu.be/T92oxFrOA6M SC 09 Consider installing a three-phase power supply to your house if you don’t already have it. This will allow more charging power (and less charging time). My electrician said that adding three-phase power to a typical home would start at about $3,000 plus utility fees. It will be more expensive if power is supplied to the house via underground cables rather than overhead wires. 10 If you live in an apartment complex, find out whether you can get permission from your owner’s corporation to install charge points, likely at your expense. EVs have been banned at an underground parking garage in Germany due to fire risk, and this ban could conceivably extend to underground garages at apartment complexes, including in Australia. See siliconchip.au/link/abka Editor’s note: from October 2023 in NSW, new apartments must have the ability to charge electric cars; see siliconchip.au/link/abkb 11 What if you have to park your car on the street? Local councils have fined some people when they have run cables from their houses across footpaths to charge EVs. To alleviate this problem, some local councils are trialling schemes where a cable is run from a resident’s home, under the footpath and to a location near the gutter with a charging point, at your expense, of course – $6,000 plus other costs. You would have to hope no one took the adjacent parking space! See siliconchip.au/link/abjr 12 An Australian company that makes such charge points is Kerb Charge (www.kerbcharge.com.au) – see Figs.25 & 27. But also keep in mind that there are usually council regulations against blocking or placing obstacles on footpaths (eg, to ensure people in wheelchairs can get about), so you would need to verify you would not get in trouble before installing such a device. 26 Silicon Chip Australia's electronics magazine Fig.27: the inventor of the kerb charger, Rod Walker from Kerb Charge (www.kerbcharge.com.au). Source: www.portphillip.vic.gov.au/ media/1uwb0n2f/img_1574.jpg siliconchip.com.au