New standard should prevent “plug war” for megawatt-scale electric truck charging

A feature of the early days of modern electric cars was a confusing mix of different charging plug/socket combinations.

Called the Plug War, it hampered the early adoption of EVs as potential buyers hung back, worrying their purchases may not be capable of charging outside of their home if their car’s plug lost the ‘war’. Thankfully, the war has effectively been won and the CCS (Combined Charging System) now predominates in new vehicles.

However, there is a limit to the capacity of CCS connections. The CCS DC plug tops out at around 350kW and 500 amps. For cars that is fine – at that pace a car with a 64kWh battery could be 0 to 80% charged in as little as 8 or 9 minutes: barely time to do a coffee or toilet stop (and little slower than current hydrogen refuelling systems).

On the other hand, when it comes to trucks doing long-haul runs with 200kWh to 400kWh (or more) in their batteries – 350kW would not be fast enough.

At that rate, it could take an hour or more to charge the largest batteries. This in fact has been the argument put forwards by the proponents of swappable battery technologies, such as Janus, and hydrogen fuel-cell technology for long-haul EV trucks. (As discussed in my recent article on EV trucking).

A larger power connector is therefore vital for making long-haul electric trucks time competitive with their diesel brethren. (As are the chargers and electricity infrastructure to go with it). However, one important issue for any higher power connector is the avoidance of another Plug War resulting in different plug shapes and communications protocols.

For a while it seemed one was in the wings as Tesla were talking about developing their own Megacharger plug, CharIN (a consortium of car and charger manufacturers overseeing the development of industry-wide plug standards) doing a slow but steady development of another and current EV truck manufacturers simply fitting the CCS plug to the trucks they build.

It seems that issue, at least, is close to sorted with the recent announcement from CharIN launching an agreed set of draft specifications and a charging plug layout for what they are calling the Megawatt Charging System, or MCS. To go with the announcement, CharIN showed a prototype MCS fitted truck and MCS charger at the recent EVS35 show in Oslo, Norway.

As Tesla is now part of the CharIN consortium (and have held off announcing their truck charging system specifications) it would seem most likely it will adopt MCS for the upcoming production launch of the Tesla Semi. (Interestingly, the CharIN name for this new charging system is the one Tesla gave theirs back when they first announced the Semi).

Importantly, CharIN made the point that the MCS standard, whilst vital to make long-haul EV trucking a reality, will also pave the way to electrifying other heavy duty transport areas such as ferries and aeroplanes along with mining and agricultural equipment.

Some of the key specifications of the MCS include a capability of up to 1250 V/3000 amps, backwards compatible with CCS (presumably through an adaptor) and V2X (bidirectional) capacity. That last is interesting as it would allow large truck and machinery batteries to double up as significant power sources during emergencies.

An additional feature of the draft standard is mandating position and height for the vehicle socket. For trucks this would be on the left hand side of the vehicle at approximately hip height.

(Something owners of EV cars can only wish for as the charging plug is in a different spot in almost every EV made and making it hard for many EV owners to actually park within a marked EV charging spot and still have the lead reach the charging port).

Coupled with the Megawatt charger will be the need to build some sort of storage battery buffering – after all, drawing one megawatt of power from the grid can be problematic in many places, let alone if several EV trucks were to pull in at once for charging.

Therefore, as part of the ‘first of its kind’ public electric truck charging site (in Portland, Oregon, USA) the installation will include both MCS charging AND battery storage to back up the grid at times of high demand.

The draft CharIN standard is now out for public comment and it is expected the finalised specifications will be released in 2024.