The SAE standards group has officially updated the J1772 standard to change DC fast charging from its previous limit of 50-500 volts at 200 amps to 0-1,000 volts at 400 amps. The updated specification was published in October, 2017 although it has not been widely reported.
People commonly talk about the upcoming high power generation of DC chargers as being “350 kW” but the actual international specifications are all aligning to support 400 amps at 1,000 volts which is a peak theoretical 400 kW. Actual vehicles charge at lower rates determined by their battery configuration and design. Typical charging voltages range from 300-400 volts although future cars like the Porsche Mission E may be capable of charging at twice that voltage.
The SAE J1772 specification describes the AC charging plug and inlet also known as a “charging coupler” design for EVs sold in North America, Japan, and some other areas except for vehicles sold by Tesla. Tesla’s design uses the same basic pins and signaling but with a proprietary physical plug design. Tesla sells a J1772 adapter in order to provide AC charging compatibility. The same J1772 document also specifies DC charging by adding 2 additional DC power pins.
Europe and some other areas use a different physical coupler design which shares the signaling design used in J1772 but adds 2 extra pins in order to support 3 phase AC which is more common outside of the U.S. and Japan. This design specification is defined by another standards group known as the IEC. The IEC standard is being updated and has not officially been published yet.
Last year the CHAdeMO standards group in Japan updated their DC charge coupler specification to support 500 volts at 400 amps (200 kW) from its previous limit of 500 volts at 125 amps (62.5 kW). Efforts are under way to increase that again later in 2018 to 1,000 volts at 400 amps which will match the new SAE J1772 limits.
China has their own AC and DC charging standards commonly called GB/T (which is actually the name of an entire category of Chinese standards). The GB/T DC coupler is believed to already support 1,000 volts at 400 amps.
Some new charger products from ABB and ChargePoint document support for DC charging at 500A under some some configurations.
Actual charger products capable of supporting these high power levels are just beginning to be delivered and installed.