It seems certain that electric vehicles (EVs) will become an increasingly common sight on the world’s highways. From a starting point of around 400,000 such vehicles worldwide at the beginning of 2014, the total figure looks set to double on an annual basis for the foreseeable future as the consequence both of changing customer attitudes and a mix of governmental incentives and pressures.

But EVs cannot simply be charged up in a matter of the two minutes or so it takes to refill a car running on petrol or diesel. For now, an EV must be connected to a charging station that will inevitably take much longer – a period that may be measured in hours not minutes - to recharge a battery from near zero to full capacity.

So how are the automotive and recharging technology industries ramping up to meet the challenge of compressing the timescales involved?

Slow vs, Fast Recharging

IHS Automotive analyst Ben Scott confirms two basic divisions in the market for recharging devices. One is between methodologies that rely on relatively slow recharging from domestic electricity supplies and those that provide a much higher-powered input (and therefore more rapid recharging) from a public charging station. The second is between charging methodologies that input alternating current (AC) to the car which will then necessarily have to be converted to direct current (DC) by on-board hardware before it is fed to the battery and those that input DC directly to the battery.

How these might be used in practical terms will, in turn, depend on a number of variables. AC input from a domestic supply generally requires several hours to charge a battery up from flat to full. This approach is, therefore, the obvious option at times when the car owner can leave the vehicle plugged in for an extended period, say overnight.

A BMW gets an AC recharge via a Schneider Electric wall box. Source: Schneider ElectricA BMW gets an AC recharge via a Schneider Electric wall box. Source: Schneider Electric
In contrast, both AC and DC can be used for higher-powered public recharging although DC may make more sense because conversion hardware can be incorporated in the recharging station. As far as the actual power input to the vehicle is concerned, Scott says that AC charging using domestic power and the vehicle’s own on-board equipment might be rated as low as 3kW. A public DC charging station, by contrast, might deliver as much as 50kW.

But the reality is not quite as clear cut. For a start, some vehicles will allow for 6kW or more of domestic AC input if the owner has a wallbox fitted at his or her home to permit enhanced power delivery. In addition, AC even at a low rate can still be an option for non-domestic recharging in situations where a car is stationary for an extended period, for instance at an office or shopping carpark.

Another factor in the equation is cost. Scott says that the hardware for a public DC recharging station might easily cost the equivalent of $30,000-$40,000, whereas that for a comparatively low-powered AC recharge device might cost as little as $1,500. On the other hand, there is no theoretical maximum to the rate at which DC power could be input, although Scott cautions that it is unclear whether or not repeated high recharging sequences might reduce battery life, something that could pose serious financial consequences for the overall economics of EVs.

As such, Scott says that when public and domestic recharging stations are taken into account, then AC will predominate for the foreseeable future. He says that IHS estimates that by 2020 there will be around 12 million recharging stations of all sorts worldwide, but that 2% of them will be DC installations.

Scott also says that the U.S., Western Europe and parts of Asia are the main areas where recharging networks are currently operating. He says that the physical geography of a country can be a factor that facilitates the introduction of such networks. For example, a “long, thin” country in which charging stations can be installed along a few major roads running from one end of the country to the other is ideal territory, quite literally. In Europe, Norway is a prime example, although Scott says that government policy there is also encouraging drivers to adopt EVs.

The Connection Quandry

Another issue that complicates attempts to construct public recharging networks – whether AC or DC – is that of standardizing the physical connectors that lock the charging cable to the vehicle’s recharging point. This issue is complex, but there are essentially two main categories: one called CHAdeMO for DC only that originates from Japan and one known as SAE J-1772 for AC. The latter approach is published by the U.S. Society of Automotive Engineers, but it was developed with European input so that it exists in two different configurations -- the original U.S. Type 1 and a European Type 2 -- as well as in two "combo" versions in which the AC connector is integrated into a single housing with an additional DC input connector. Hence there are two AC-only connectors – known simply as Type 1 and Type 2 with the first predominantly for use in the U.S. and Japan and the second in Europe, along with two corresponding Combo 1 and Combo 2 versions.

Scott says Type 1 is primarily used in the U.S. and Japan, although there will be a few Type 1 units in Europe. Type 2 is the European standard and is "becoming the de facto standard" for AC charging, he says. "It is likely we will see less and less of Type 1 in Europe.”

Depending on the car maker, electric vehicles may be equipped with one each of the two different types or a Combo which will enable them to use either AC or DC recharging. In general terms, a car from, say, a Japanese manufacturer would likely have a CHAdeMO connector plus a Type 1 or Type 2 Combo depending on whether they were to be sold in the U.S. or Europe. A vehicle from a German company, meanwhile, would likely have just a Combo 1 or Combo 2. One car maker –- French company Renault -- only supplies vehicles with an AC connector, but equips them with an on-board AC-to-DC conversion capability that enables them to be fed with AC power at a much higher rate than a domestic source would provide.

Dr. Colin Herron, managing director of Zero Carbon Futures, a consultancy and low-carbon technology development company based in England, says that the company (which is a unit of Gateshead College) is involved in a project called Rapid Charge Network. The project aims to install 74 "dual standard" rapid charging stations made by French company DBT and provide both DC and AC recharging – the former at 44kW and the latter at 43kW -- across the UK and Ireland. Other partners in the project include Volkswagen, BMW, Renault and Nissan.

The first of the stations was inaugurated in September at a motorway oasis near Coventry in the UK. Herron says the network should be completed by early 2015 when it will offer one of the first multi-standard recharging units in public operation in Europe. When it is, the mainland network will form a spine reaching from London to Stranraer and on the west coast of Scotland. Halfway up, lateral links will stretch out east and west, the latter to Holyhead on the island of Anglesey at the northwestern tip of Wales. The importance of the Stranraer and Holyhead locations is that they connect by ferry to Belfast and Dublin where there also will be recharging stations. In this way, the network will extend to both the north and south of Ireland.

Herron says that in order for the network to comply with both the CHAdeMO and SAE standards (the latter referred to in Europe as combined charging system, or CCS) the network must use recharging stations that can provide drivers with a choice of three cables to attach to their car, each with a different connector: a CHAdeMo, a Type 2 and a Combo 2.

Standardization Standoff?

There seems to be little likelihood in the near term of consolidating this number from three to two or even one connector. Herron says “standardization is set at the current level of confusion. We are caught between the automotive powerhouses of Germany and Japan and will remain so unless either the German or Japanese OEMs agree that one of them has lost the argument and adopts the other’s standard." He says one of the only routes left to remove the plug connector is to fully develop induction charging. Herron also says that for the most part, installing recharging stations is fairly straightforward although on occasion some upgrading of the local grid infrastructure – such as transformers – may be necessary.

Nevertheless, this situation is arguably the result of competition to develop optimal technologies in a young market, which suggests that a degree of convergence will inevitably follow. That is the view of David Greave, director of EV infrastructure business for the UK, Ireland and the Nordic Baltic zone for French-owned multinational recharging hardware manufacturer Schneider Electric. His company has been in the market for six years and provides recharge kits for both domestic and public use.

On the domestic front, Greave says that though it is feasible simply to plug an EV into a wall socket and rely entirely on on-board hardware to control the recharging process, the reality is different. In practice, car owners generally use a wall-mounted box conforming to an International Electrotechnical Commission (IEC) standard known as Mode 3. This standard enables automatic adjustment of the rate of charging according to both the car’s AC-to-DC conversion capability and other demands that may be made on a residential housing unit's electricity supply.

The boxes that Greave refers to are designed and made for a particular manufacturer, and Schneider is one of the largest suppliers worldwide of these boxes, including for BMW. He cites the recharge unit for the BMW i3 EV, which he says can provide up to 7.4kW of power – representing an actual current flow of 32 amps – enabling the vehicle to be recharged completely from a domestic source in three-and-a-half hours.

Greave also identifies two market sector developments that point to continued evolution in terms of standardization and technical innovation. First, the European standards organization CENELEC has addressed the issue of connecting EVs to recharging sources by mandating that from 2017 there should be a single Type 2 connector in use on the Continent for connecting recharging cables to wallboxes. He says that although this is already largely in practice, the move means that a standard approach will soon be unavoidable.

Second, Greave says that domestic wall boxes able to deliver DC charging at 20kW to EVs will become much more common. Some units have already begun to appear and he confirms that Schneider is developing a product for this application.

As a result, even if little immediate prospect exists for a single, global rapid-charging system, other ways exist in which the market is moving towards a more user-friendly mix of recharging options for the growing number of EV drivers.

More Resources:

IHS Automotive

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