An early goal was to increase the mechanical strength of the coupler but reduce its size. In monthly meetings held throughout late 2018 and 2019, CHAdeMO and CEC expanded the goals for the new standard. Those discussions culminated in a gathering of international EV charging experts in Tokyo for the 1st International ChaoJi Technical Workshop in July 2019.

Blech wrote, “Harmonizing with China’s GB/T is one way to achieve these cost reductions by the economy of scale. China accounts for almost 80 percent of all fast chargers in the world.” CEC members performed the early-stage design work and prototyping. The Chinese and Japanese teams then mutually ensured that the new joint ChaoJi standard would be backward compatible with existing CHAdeMO and GB/T versions.

Test criteria due in 2021

Project leaders claim that if automakers utilize an 800-volt battery system, twice as much range could be added in the same time. The first demo events and trails – using liquid-cooled connectors and a max current of 600 amps – were conducted at UL Japan Kashima EMC testing laboratory in Chiba prefecture, Japan, on February 6, 2020. The testing criteria for CHAdeMO 3.0 certification, currently being written, will be released in 2021. In the U.S., CHAdeMO has accreditation as a standard managed by IEEE.

SAE International’s J3072 standards committee is finalizing updates to meet bi-directional charging requirements to the latest IEEE 1547-2018 standard, according to Rich Scholer, SAE Hybrid PEV Communication and Interoperability Task Force chair. The J3072 standard is focused on AC capabilities rather than DC. IEEE 1547-2018 is also used for SAE DC Chargers capable of bi-directional use, Scholer noted.

Under the ChaoJi design, CHAdeMO and China’s GB/T chargers use the same hardware. However, a special inlet adapter and a dedicated bi-directional charging sequence had to be devised to ensure full-backward compatibility of ChaoJi vehicles with the existing bi-directional CHAdeMO chargers that have this optional feature. Blech wrote, “It was quite a challenge to add a new function with the reduced number of signals, while also ensuring robustness, electromagnetic immunity, and full backward compatibility with the existing CHAdeMO, GB/T, and CCS [Combined Charging System] systems.”

 “How the battery systems are designed in addition to compliance with the specification and standards will depend on the strategy of each vehicle OEM,” wrote Blech. “But one thing is for sure. The introduction to the EV market, possibly in the mid-2020s, of solid-state batteries capable of accepting ultra-high charging rate without the expensive thermal management system, will be a significant breakthrough.”