Recharging

Conventional vehicles can refuel very quickly. Recharging an electric car is very much slower. Various schemes have been proposed to accelerate charging. Hybrid vehicles and battery swapping, as practiced in industrial applications and as proposed e.g. by “Better Place”, that filed for bankruptcy, are often cited as possible approaches. Remarks on hybrids I have relegated to my Links Page. There are some good reasons to rate these approaches as “transitional”. To invest though in transitional systems can be a risky undertaking. Should e.g. batteries in this case evolve faster than projected, such investments may never reach their pay-back. A Hybrid is also a very complex piece of machinery compared to an only electrical vehicle. Such complexity tends ultimately to end up in uncompetitive costs.

In Europe the network of places where electric cars can be recharged is growing rapidly. According to LEMnet a large number of stations are as yet limited to 240V/16A or 3 phase 400V/16A (11kW) and only relatively recently three phase connections at 400V/32A (22kW) are becoming more common. It is also interesting to note how developed accounting for consumers and providers already can be. A good example for such a system is offered e.g. by Coulomb Technologies. For very fast charges DC-DC connections are needed with additional electronics in the locally fixed charging station, making such chargers more expensive than current AC charging points that rely on the car’s electronics. Calculations often made to prove that fast recharging is impossible, neglect that it is of course possible to discharge a stationary battery to buffer the short burst. Such buffers are also planned to become part of the Tesla fast charging stations (Superchargers) now being installed in the US and Europe. These stations represent the current state of the art, being able to charge a Tesla Model S at up to 130 kW. Further improvements are of course possible. Tesla e.g. aims at being able to deliver a signifcant charge within 5-10 Minutes. 

Some Automakers have agreed in May 2012 to support a "Combined Charging System for AC and DC fast-charging from single inlet port". Tesla Motors is installing in the US, Canada and Western Europe its own powerful fast charge network. For current owners of the new Model S recharges at those stations are free. The network is expanding steadily. The actual status can be found at supercharge.info.

On 31. May 2013 Tesla Motors had announced that construction of this network would be significantly accelerated and that, on the basis of these plans, the USA and Canada will be essentially covered within a year. For Europe Tesla stated in September 2013: "By the end of 2014, 100 percent of the population of Germany, the Netherlands, Switzerland, Belgium, Austria, Denmark and Luxembourg will live within 320 km of a Supercharger station, with about 90 percent of the population in England, Wales and Sweden living within the same distance of a charging station". The power these stations will be capable of was raised at the same time to 130 kW that, according to Tesla, should enable a Tesla Model S to "replenish three hours of driving in just over 20 minutes”. By March 2015 these targets had essentially been reached and further expansion into Southern and Eastern Europe is proceeding apace.

Note also the relationship between range and the number of stations needed. Tesla vehicles with their much greater range than any other purely electric car on the road so far, do also need correspondingly fewer charging stations. Tesla's decisive move, far ahead of anybody else in the US and Europe, creates an interesting precedent and will be a powerful sales argument for their cars. Some details of the agreements with the location owners can be found here.

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There is a tendency in Europe to call for extensive safety measures that are exceeding by far what is current practice for refueling with highly flammable liquids, ignoring completely that most citizens on the road have so far and by definition survived plugging in their hair dryers. Some of these "precautions" are mostly just thinly veiled attempts at locking consumers into local or national monopolies. Some agreement seems to have been reached on the shape of the plugs. Tesla Model S cars sold in Europe are delivered with a  "Mennekes" (Type 2) connector to charge with 3x32A (22kW)  in addition to a connector to a red CEE for 3x16A (11kW) charging. Supercharging from Tesla stations at 130kW  is also possible across this connector on the car side. Also for the Roadster a cable with this Type 2 plug on the station side has become available. An overview over the standards discussions can be found here.

Charge point location needs rethinking. We should not be distracted by our conditioning to “service stations”. A pattern that seems to emerge is a kind of “duality”. Most of the time the car is charged at home in its own garage or parking space. Only when driven sporadically over larger distances, charging en route is needed and then charging is most convenient where the owner would pause anyway. The shorter the planned pause, the more power the charge point should be able to provide and the more pleasant the surroundings for a 1-2 hour stop, the more likely it will be also used. So a restaurant or shopping mall should provide more powerful charge points than a hotel would have to reserve for its overnight guests.

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The International Electrotechnical Commission (IEC) modes definition:

  • Mode 1 - slow charging from a regular electrical socket (1- or 3-phase)
  • Mode 2 - slow charging from a regular socket but which equipped with some EV specific protection arrangement (e.g., the Park & Charge or the PARVE systems)
  • Mode 3 - slow or fast charging using a specific EV multi-pin socket with control and protection functions (e.g.,SAE J1772 and IEC 62196)
  • Mode 4 - fast charging using some special charger technology such as CHAdeMO.

The French initiative to promote charging infrastructure in residential parking lots and garages makes a lot of sense in this context. The often voiced claim that introduction of electric vehicles critically depends on access to a large number of public charging stations scattered around cities should be revised. A Tesla Roadster, if e.g. used for commuting, will usually need nothing more than its charging point at home, as few would have daily commutes over 200 km: A range this roadster can manage with ample reserves at motor-way speeds between 100-120 Km/h in its battery life protecting “Standard Mode” - even in wintertime with snow tires and heating. 

Between the extremes of a short range supported by fast recharges and a relatively long range with mostly slower charging, a lot of combinations are possible. What is convenient depends evidently on the car’s usage pattern. Tesla Motors offer several battery options for their Model S. As customers will be able to choose, the market will gradually adapt to customers preferences and these may not everywhere and for everyone be the same. Tesla Motors recently announced that their 40 kWh option, their smallest battery for the Model S, has been dropped for lack of demand. 

We should also remember that customer surveys relating to unknown products are notoriously unreliable and anecdotes about consequent marketing mishaps abound. Introducing new products entails uncertainties and only once a novelty has found its loyal community, the picture becomes clearer. Tesla staff mentioned the phenomenon of the “vanishing range anxiety”. A new customer explores the range of his electric car gradually and uses it more and more generously as practical experience raises his confidence: a pattern confirmed in BMW’s fleet tests