Slow, Fast and Super: EV Chargers Conundrum
Some time back, the Indian Transport Minister set an audacious goal for India to achieve 100% electric mobility by 2030. Now, goals and ambitions are good for both individuals and countries. However, as we all know, proper infrastructure is to key to success. British administrators created railway infrastructure in India about 170 years ago, and since then it has become life line of Indian economy. Therefore, for EVs to become mainstream, India must establish its EV charging infrastructure. Given the current predominance of Lithium-ion batteries, the creation of EV charging stations or “EVSE” is of paramount importance.
EV Charging Stations
A typical charging station is usually a fixture connected directly to an electric outlet or to a distribution panel. It consists of one or more charging cables equipped with a connector (that is quite similar in shape to a petrol pump nozzle), in same fashion it simply connects to the EV’s charging socket.
The station has lights that indicate that the EV is connected and charging. It can also have a button for starting or stopping the charging operation. Some of the advanced charging stations boast of additional functionalities such as; energy metering, electronic payment integration, card-controlled access system and Internet based cloud connectivity. Formally, electric charging stations are called EVSE.
EVSE: Stands for “electric vehicle service equipment.” It is the intermediary between a power source and the vehicle’s charging port, and is typically mounted on a wall or up on a pedestal. Its role is to simply relay the AC power to the vehicle safely.
Different Types of EV Chargers
At the first sight, charging an electric car seems to be a simple process, implying that one can plug one’s car into a charger that is connected to the electric grid. However, it is not as simple. It depends on the types of EVSE that one has deployed. In some cases, specially, in personal garages one connects the cable on one end to a domestic power socket and the other end to the car’s charging port. However, many more sophistication have emerged which we will have a review of.
EV chargers typically fall under one of three main categories: Level 1 charging stations, Level 2 charging stations, and DC Fast Chargers (also referred to as Level 3 charging stations).
As we see, from the above table, some chargers are faster than others. And, not only this, but we must also realize that different electric cars need different types of charging ports.
This brings us to the concept of On-board charger. The actual charging device for Level 1 and Level 2 charging comes factory-installed in the car and is called the “on-board charger.” It converts AC power from the wall to DC power that charges the battery in the vehicle. The charging speed may vary, but the most common on-board chargers are 6.6 kW on battery electric vehicles (BEVs) and 3.3 kW on plug-in hybrid electric vehicles (PHEVs). As shown in the figure above, the connector styles are also different depending on the type of “OBC”.
Level 1 Chargers
Level 1 chargers simply use a plug to connect to the on-board charger and a standard household (120v) outlet and are typically used in North America. These are the slowest chargers. However, unlike other chargers, Level 1 chargers do not require the installation of any additional equipment and are popular for residential use. They are the least expensive EVSE option. While this option may not look great, it works for those commuters who travel less than 40 miles a day and have all night to charge. Some popular manufacturers of Level 1 EV chargers include AeroVironment, Duosida, Leviton, and Orion.
Level 2 Chargers
These chargers must use an EVSE to provide power at 220v or 240v and up to 30 amps. Level 2 chargers are used by both residential and commercial charging stations. They, however cannot be plugged into a standard wall outlet and require professional installation. Such chargers can fully charge an electric car battery within two hours. This makes them an ideal option for commuters who need fast charging and businesses who want to offer charging stations to consumers as a perquisite while they shop, bank, or have a meal. The popular Level 2 chargers manufacturers include ClipperCreek, Chargepoint, JuiceBox, and Siemens. Many electric car manufacturers, like Nissan, have their own Level 2 charger products. Currently, effort is on to improve charging capacity of these chargers to further reduce the charging time.
Level 3 or DC Fast Charging
Since most users of EV wanted faster charging in lesser time, the fast charging DC chargers emerged. Initially, Japanese took the lead as they had the cars ready viz, Nissan Leaf and Mitsubishi i-MiEV. They developed the chargers known as CHAdeMO EV charging stations. There is an interesting story behind this name. According to Wikipedia, CHAdeMO is an abbreviation of “CHArge de MOve”, equivalent to “move using charge” or “move by charge”. The name is derived from the Japanese phrase O cha demo ikaga desuka, translating to English as “How about a cup of tea?”, referring to the time it would take to charge a car.
This type of charger looks like a typical petrol pump-sized machine. It can add 60 to 100 miles of range an electric car in just 20 minutes of charging.
Unfortunately, CHAdeMO charging infrastructure did not grow very fast. The reason being that other automakers lobbied against CHAdeMO deployment because it was not an SAE authorized standard. It was standard co-developed by TEPCO (Tokyo Electric Power Company) and the Japanese automakers. Instead of adopting CHAdeMO, the SAE developed their own fast charging standard (Combo Charging System), Tesla Motors developed a proprietary fast charging system (Supercharger), and the Chinese developed a different fast charging standard.
Emergence of CCS/SAE Combo type of DC fast Chargers
When SAE was asked to develop a DC fast charging system by non-Japanese automakers, the SAE J1772 committee basically took the existing J1772 plug and added on two large pins for high power DC. The upper part is the ordinary J1772 plug used in the USA, and the lower portion are the two DC power pins.
Among the reasons the J1772 committee developed CCS are single charging inlet to support slow and fast charging (versus two required for CHAdeMO)
Since the same connector serves multiple purposes, it allows car makers more freedom by needing only a single charging port in the skin of the car.
Also, going forward, smart grid protocols would be used to control charging. The point being the control protocol between the car and the charging station. CCS uses PLC for this communication, whereas CHAdeMO uses CAN. It must be noted that CAN is a data protocol used between components inside cars, whereas the PLC is part of the smart grid protocols. Therefore, the smart grid connectivity would be better served by CCS type of chargers.
As can be seen from the above picture, there are four or so DC Fast Charging systems currently being used by electric car manufacturers. The picture shows four different connectors.
At the current moment the leading car for each type is:
- CHAdeMO — Nissan Leaf
- CCS/SAE Combo — BMW i3
- China GB/T — Chinese Models
DC fast-charge stations generally support both standards. All carmakers adhere to one of these standards, except Tesla, which has developed a higher-performance charging station, “Super Charger” but offers a CHAdeMO adapter as an option.
“Tesla Super Charger”
Since Tesla considers itself to be the market maker in the EVs world, it took advantage of the fact that there is no single standard for fast-charging. Therefore, it developed what it calls Tesla Superchargers which have a max power output of 120 kW. These super-fast charging stations can charge a Tesla battery in about 20 minutes and are being widely installed across the United States.
It must be noted that:-
- The Tesla mobile charging unit comes with adapters for every kind of power outlet, from 120 volt 12 amp (NEMA 5–20), through to 240 volt 50 amp (NEMA 14–50).
- Via an adapter, it can connect to J1772 charging stations
- At a Supercharger station (pictured above) it can receive DC fast charging at up to a 120 kW rate.
It means a Tesla Model S or Model X owner can get rapid charging in a wide range of situations. Tesla Motors also sells an add-on adapter allowing a Model S/X owner to recharge at a CHAdeMO station.
Summary of EV Charger types
The table below from SAE summarizes current state of various EV chargers currently in vogue, it includes both AC and DC chargers. It proposes the development of AC Type 3 and DC Type 2 & 3 Chargers in the future. Naturally, CHAdeMO is not included in this chart as SAE considers it to be a non-standard type as is the Tesla Super Charger for now.
Emergence of Induction Chargers
Another type of chargers based on inductive charging are coming into vogue. Inductive charging (also known as wireless charging or cordless charging) uses an electromagnetic field to transfer energy between two objects through electromagnetic induction.
Advantages of inductive (wireless) charging
It has several advantages such as:
- Ease of operation and amenable to automation of the charging process.
- User comfort as no cable connections are required and the driver can simply drive over the induction plate to charge. Great advantage in adverse weather conditions.
- Automated charging as the inductive charger is placed on the parking slot, at home or at work.
- The system is safe against vandalism, misuse/abuse and environmental influences (e.g. humidity) because all devices are encapsulated in the vehicle and the ground
- There is no negative impact on the cityscape (all devices are hidden in the ground)
One innovative player called PLUGLESS is popularizing wireless inductive chargers for existing EVs also as shown in the above picture.
Over and above, the earlier mentioned stationary charging advantages being the inductive charging offers many more possibilities for en-route charging.
The potential of inductive en-route charging
With inductive en-route charging, EVs could be charged while standing at the traffic light, the bus stop or the taxi stand while it should be impracticable with the conductive charging option. So, using wireless inductive charging, these short timeframes could be used to charge the EV and hence its range. The charging method above is called static inductive en-route charging because the vehicle is standing still while charging.
In addition, there is also the possibility to charge the vehicle while it is actually moving. This charging method is called dynamic inductive en-route charging. This charging method holds the potential of giving the driver virtually limitless range as long as he stays on paths specifically adapted for dynamic inductive en-route charging.
QUALCOMM is a leading proponent of this technology and it has developed what it calls Qualcomm Halo dynamic electric vehicle charging (DEVC). Based on the DEVC technology many new innovations in inductive charging are coming into vogue which allow cars to charge both while parked and while on the road
Implications for India
Given this backdrop and the fact that the penetration of EVs is still minuscule in India, the choices are many. Some of the decisions making that need to be made are:
1. Adoption of a specific charger protocol given the scenario possibly for India, SAE combo would be a more appropriate choice.
2. India could also like in Telecom, leapfrog directly to wireless inductive technology. This has advantage as India has relatively less public space and propensity to vandalize public infrastructure is high. This technology would take care of both the above aspects. However, the costs factors could be huge in short run.
3. The other emerging competitors such as Battery Swapping may makes sense in a country like India, which has wholeheartedly adopted ‘sharing economy’. The current bottleneck is non-standardization of batteries used in EVs.
4. In a still futuristic scenario, flow batteries or metal air batteries may become technology of choice whereby the existing fossil fuel infrastructure can be revamped to fill fresh electrolyte in such batteries and remove spent electrolyte. This scenario is shown in picture below.
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