Tesla Supercharger stations at Harris Ranch, California, in April 2013 [photo: TeslaTap.com]
There are currently three standards in use for electric-car DC fast charging.
The CHAdeMo standard is used by the Nissan Leaf, as well as the low-volume Mitsubishi i-MiEV and Kia Soul EV.
The majority of U.S. and German carmakers have signed on to use the Combined Charging Standard (CCS), although fast-charging equipped models from these companies have only recently begun to proliferate.
And Tesla has its own Supercharger standard, with company-operated charging stations that are free for Model S owners to use.
So for today's electric-car owner, the availability of DC fast charging often depends on what car he or she is driving.
Tesla is also taking a different approach to the deployment of stations than carmakers using the CHAdeMO and CCS standards, notes Charged EVs.
NRG eVgo electric-car charging station
Tesla--which sells cars with more than 200 miles of range--has positioned its Supercharger stations to encourage long-distance travel.
In contrast, supporters of the CHAdeMO and CCS standards have employed a "clustering strategy," building most stations in and around urban areas.
For those networks, providing confidence to drivers within metropolitan areas can be as important as facilitating intercity travel, Arun Banskota, president of network operator NRG eVgo, said.
That's because the electric cars using CHAdeMO and CCS aren't fitted with battery packs large enough to make routine intercity trips practical.
And while Nissan has worked to build out the network of CHAdeMO stations roughly since the launch of the Leaf over four years ago, the CCS network has some catching up to do.
The first public CCS station opened in October 2013, but CCS-equipped cars did not start to become widely available until the middle of 2014.
BMW i3 and Volkswagen e-Golf electric cars using Combined Charging System (CCS) DC fast charging
So until fairly recently, there hasn't been much incentive to build up a network for what was a fairly small number of cars.
That's beginning to change though.
Nissan will likely continue to support charging-station construction, and BMW and Volkswagen are teaming with ChargePoint to install 100 CCS stations on heavily-traveled East and West Coast corridors.
NRG eVgo officials have also said that the network plans to concentrate more on intercity travel.
More stations will be needed as carmakers introduced more long-range electric cars.
Audi plans to bring a Tesla-fighting electric SUV to market in 2018, and the Chevrolet Bolt EV and next-generation Nissan Leaf are both expected to have 200-mile ranges.