Fast Vehicle Charging Goes by Many Names

Getting dozens of different plug-in vehicles to seamlessly connect and talk to dozens of various chargers is no easy feat. For several years now, a handful of national and global standards organizations, led by the Society of Automotive Engineers (SAE), have been developing standards for plugs and vehicle charging equipment. Despite these herculean efforts of those involved, there's still a lot of confusion about how to refer to the fastest rates for charging vehicles.

The agreed upon (as anointed by the SAE) standard charging rates are known as Level 1 and Level 2 and refer to alternating current (AC) charging equipment. (Equipment on the vehicle itself converts the AC to the DC used to actually charge the batteries). These slow and medium speed charge rates will be offered by nearly every piece of home or commercial charging equipment, from companies including Coulomb Technologies, Ecotality, Eaton, Better Place, AeroVironment, and others. These specific charge rates for Level 1 and Level 2 (1.44 kW and 6.7 kW respectively) will get most vehicles fully charged in as little as 2-5 hours.

But many of these companies anticipate demand for charging in less than an hour for vehicles that are either being used for longer trips, don't have a convenient place to charge at home, or for people who just don't like to wait. Enter direct current (DC) charging, which can cut charge times in half. To input DC power into your vehicle, the car will have to be fitted with a special cable and connector. DC charging equipment that is generally not permitted at most homes because of the huge consumption of power and safety issues. The Tesla Roadster and others provide DC charging cables as an option.

Confusion about Names and Terms

Since there has been no specific global standard passed for this type of charging, EV charging equipment companies have been developing products at a number of charging speeds and have been referring to it in multiple ways. These include rapid charging, fast charging, Level 3 (and sometimes Level III, with Roman numerals) charging, or simply "DC charging." In Japan, the Tokyo Electric Power Company (TEPCO) has created a version of DC charging equipment that has received international support by a group that wants to base a "ChadeMo" standard on it. Here in the U.S., TEPCO is also gaining some support, while other SAE members are holding back on any endorsement and could develop an alternate Level 3 standard.

The use of the term "Level 3" is contentious because Levels 1 and 2 are SAE standards and refer to AC charging equipment, and the SAE hasn't weighed in on a Level 3 standard for AC charging. Level 3 DC charging has only been loosely described by industry folks as fitting within a range of voltage and amperage combinations. For example, AeroVironment has DC charging equipment products for three different rates (30, 50 and 60 kW), and compatibility with the CHAdeMO protocol is an option.

Stop Using "Level 3" Name, Until We Know What It Means

No Level 1 or 2 standards have been drafted by the SAE for DC chargers. Some engineers (many of who participate in standards groups) lately have been waging a battle to get charging equipment companies and the media to stop using the Level 3 terminology because there is no existing standard, and because companies that purchase equipment advertised as such today might believe that what they buy today would be compatible with other current or future DC charging equipment. I've lately had several conversations where this point was made loud and clear to me, yet at the recent PlugIn 2010 conference, several vendors continued to use Level 3 in their marketing materials and presentations.

I was hoping that asking a panel of experts at a session on EV charging would bring clarity, but no such luck. Mark Duvall of the Electric Power Research Institute said that work was still being done on a standard and would likely be done within a year. G.M.'s Gerry Kissel, who had stated in his presentation that there was no Level 3 standard (see this slide) retreated when confronted on the subject, and said that it was nonetheless okay for industry folks to continue using Level 3. To make matters even more confusing, there's debate going on whether a single plug can be developed for both AC and DC or charging, or if they should remain separate.

So the "Level 3" label seen today means proprietary DC charging hardware, and some kind of faster than medium speed, but gives no guarantee that it will make it possible to plug-in anywhere else. And if you use those words together in conversation or online, you may get a strong rebuke, or no reaction at all.