The world waits for a proper fast charging system that could handle megawatt power, required by electric trucks and potentially also in aviation and shipping industries.
This Summer (July and August) industry experts and researchers had an opportunity to meet and test their solutions at a second high-power electric vehicle charging connector evaluation, co-hosted by the National Renewable Energy Laboratory (NREL) and the Charging Interface Initiative (CharIN) with support from the U.S. Department of Energy, the California Energy Commission, and others. The first event was held in September 2020.
"The participants used NREL’s state-of-the-art Electric Vehicle Research Infrastructure (EVRI) evaluation platform within the Energy Systems Integration Facility (ESIF). They included representatives from leading vehicle manufacturers, charging equipment manufacturers, and component suppliers."
The goal is to develop a new high-power charging standard for medium- and heavy-duty vehicles called the Megawatt Charging System (MCS).
It must offer fast-charging capability for large battery packs in 15-20 minutes, which requires a power output of 1 MW and more. In fact, the current target is 3.75 MW peak (3,000 A at 1,250 V).
1 minute at 3.75 MW is about 62.5 kWh. In 5 minutes it would be over 312 kWh, while in 15-20 minutes 937-1,250 kWh.
This kind of power is more than seven times higher than the 500 kW peak in the CCS Combo. NREL notes that at 3.75 MW a single vehicle would use equivalent power to the average power needed for 3,200 U.S. homes! It would transfer the daily energy consumption of a typical home in about 28 seconds.
And we must remember that the fast-charging stations in the future must be ready to recharge multiple vehicles at the same time. Usually not all will be charged at peak output simultaneously, but in general, the installed capacity must be massive.
NERL notes that "transferring this much energy over a short duration requires unique design in the cabling, connector, and charging inlet".
"Electric vehicle charging equipment evaluation helps ensure the new standard is interoperable, meaning multiple manufacturers will be able to design and build parts that work together. Interoperability is critical to ensuring broad, consistent access to charging stations, and it will allow electric vehicle manufacturers to have confidence in station compatibility as new models come to market."
Andrew Meintz, who manages NREL's electric vehicle grid integration team said:
"We’re providing the opportunity for industry to come together, in a central location, so that even competitors can have detailed conversations on the technical merit of different equipment parameters and come to a consensus,".
According to the NREL's report, four manufacturers have come to test and refine their MCS prototypes.
"During the recent round of testing, EVRI enabled four manufacturers to evaluate designs for vehicle inlets and charger connectors. This year, the participants brought refined, molded prototype connectors based on 3D-printed proofs of concept that were evaluated in the first round. By going through the process of developing molded parts, the participants were able to not only put their designs to the test but also ensure they could be manufactured at scale."
"As with last year's event, participants checked how well the connectors fit with charging inlets and how easily they could be connected and disconnected. They also evaluated the systems' thermal performance—a key consideration in high-power charging. The expanded evaluation included measuring the strength of the locking mechanisms on the connectors; quantifying connector insertion force between dissimilar manufacturers; and judging durability. Participants provided both new components and versions that had been aged to simulate the effects of environmental conditions and repeated use at charging facilities."
It's not clear when we will see the MCS standard ready, but hopefully within a year or two. Another important thing is whether Tesla will have a separate solution, like in the case of the car plug in North America, or something compatible.
CharIN, a nonprofit association, requires developing the MCS with downward compatibility to CCS1 and CCS2. It means that there will be again two separate physical connector types - one for North America (and a few other markets), and one for Europe and probably most of the rest of the world (aside of China and Japan).
The MCS charging inlet will allow to charge from the existing chargers with CCS plugs, while the higher power output will be possible at MCS chargers via "add-on power extension modules" to the existing connector.
Here are the requirements listed by the CharIN:
- Megawatt Charging System (MCS) Up to 1250 V and 3000A
- In compliance with power classes, as defined by CharIN
- Usability of Megawatt Charging System (MCS) – Infrastructure for 1000V/500A medium power supply (current CCS connector)
- “Vehicles equipped with Megawatt Charging System (MCS) should be able to charge from the existing CCS infrastructure.”
- Coverage of Megawatt Charging System (MCS) power demand via ,,add-on power extension modules” to the existing connector
- It is required that the additional power demands be met with additional extension modules surrounding the existing CCS plug, unless its proven not to be technically feasible, following the holistic CCS charging approach.
- Downward compatibility to CCS 1 and CCS 2 (long term invest protection)
- Reuse of CCS 1/2 connector and communication with basic safety concept “as it is”
- Communication and basic safety concept shall be compliant with CCS standard
- Common set of documents at the interface EV-EVSE for requirements and test cases of Megawatt Charging System (MCS)
- Charging use-cases as baseline for requirements and definitions comparable to existing high/medium power solutions
- Support of reverse power transfer for Megawatt Charging System (MCS)
- Automated Conductive Charging as a second step for Megawatt Charging System (MCS)