ChargePoint, which plans to run 2.5 million charging stations by 2025, says the standard would perpetuate an old 'gas station' model that automakers are backing as they launch mass production of battery-powered cars.
As well as being less convenient for users, that could give too much pricing power to utilities, limiting the flexibility of charge station owners, ChargePoint says.
There are only a few million electric vehicles, or EVs, on the roads today, but with the International Energy Agency forecasting that figure could reach 130 million or more by 2030, there is a huge market opportunity up for grabs.
With Swiss bank UBS estimating the cost of building charging networks at $360 billion over eight years, there is a powerful incentive too for stakeholders to influence how they operate.
There are also risks, however, that a botched system which makes EVs harder to use could stall public acceptance, ChargePoint's Senior Vice President Product Bill Loewenthal told Reuters.
"We're at a really delicate time in the industry and getting this wrong is catastrophic," Loewenthal said in an interview.
ChargePoint, which operates but does not own its charging network, providing an Uber-like service, has a 70% share of the market for commercial charging in the United States, by its own estimate.
It has raised $530 million in 10 funding rounds from investors including Daimler, BMW and Siemens in Germany, as well as U.S. energy firms Chevron and America Electric Power.
Yet it finds itself at odds with the German automakers on some aspects of how the industry should develop.
Loewenthal was speaking ahead of the North American Conference of CharIN, an initiative backed by German automakers to support their preferred Combined Charging System (CCS) standard, that starts on Wednesday in Reston, Virginia.
In a clash reminiscent of the VHS versus Betamax videotape saga, CCS has a lead in Europe but is elsewhere up against Tesla's Supercharge system and CHAdeMO, supported by Japanese carmakers Nissan and Mitsubishi.
CHARGEPOINT VS AUTOMAKERS
California-based ChargePoint, founded in 2007, has differences of opinion with the German automakers on two aspects of the proposed ISO 15118 technical standard, known in the industry as "Plug & Charge", that will govern how cars talk to charging stations.
ChargePoint, in a research report, said Plug & Charge would set flawed rules for authenticating secure communication, inserting a middleman into an exchange that can be perfectly well handled by existing Public Key Infrastructure providers.
Further, Plug & Charge would give too much central power to utilities on pricing, to the detriment of charging station operators who want discretion, for example in managing the mix of power they generate on site and take from the grid.
These can be office managers offering an in-kind benefit to staff who plug in vehicles at work, or stores and restaurants offering a free charge to patrons to attract their custom.
More broadly, ChargePoint argues that most drivers will use slow chargers at home and work, enabling utilities to tap the battery reserves of cars on charge to balance supply and demand in their networks for much of the day and night.
Only a minority, such as taxi drivers or people going on road trips, will want to pull in for a fast charge at public stations that run on direct current.
"The reality is that people want to plug in where they work and live - and that aligns a lot with where the needs of the grid are," said Loewenthal.
High-speed chargers are "an industrial solution, not a consumer solution", he added: "It's needed, but it's not what consumers will be using in their daily lives."
(This version of the story corrects to charge station owners, paragraph 3)
(Reporting by Douglas Busvine; Editing by Edward Taylor and Mark Potter)
By Douglas Busvine