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Electric Vehicle Refueling Connectors

[Note added 28 July 2017: "Computer, show the historical documents..." This page is way out of date, referring to the sitation at the start of the modern EV era twenty years ago. Modern electric vehicles, in the U.S., anyway, all charge at up to 6.6 kW with connectors using a conductive standard known awkwardly as SAE (Society of Automotive Engineers) J1772; Tesla uses its own connector but makes an adapter for J1772 available. There remains some variation among fast-charging connectors (up to twenty times as fast as J1772!), and maybe I'll write up a page on that someday. For now, though, I'll just leave this webpage in place as a time capsule.]

There is a "Beta vs. VHS" battle, or at least "Windows vs. Macintosh", going on right now between different standards for recharging connectors for electric vehicles. GM and Toyota have lined up behind inductive connectors, like this one (actually, an updated smaller version has since been promoted as the standard):

Inductive connector

...while Ford and Honda have settled on conductive connectors, like this one:

Conductive connector

These are the dominant designs currently used for inductive and conductive connectors, but I know of at least one additional standard design of each, giving at least four mutually incompatible connector types...

A conductive connector makes electrical contact by putting metal conductors in contact with each other, just like an ordinary 110-volt plug; the multiple holes you see in the faceplate of this connector are for data connections, so that the wall- or floor-mounted charging unit to which the connector is attached can communicate with the vehicle's computer to decide how much electrical charge is needed and how fast it should be put in. By contrast, there are no metal-to-metal connections on an inductive connector; both power and data are transferred by magnetic fields. For data, this amounts to very-short-range radio; for the battery-recharging power transfer, you can think of the inductive charging "paddle" in the picture at the top of this page as being one half of an electrical transformer, with the other half being built into the vehicle.

Advocates of the inductive charger stress that there is no exposed metal to give you a shock; I've heard the term "lickably safe" used, meaning that you can stand in a puddle of water in a rainstorm, put one hand in the charging slot of the car, and lick the inductive charging paddle, and you still won't get shocked. "Well," reply the partisans of the conductive charger, "how often are you going to do that?" They point out that all the metal parts of the conductive charging connector are covered up and unpowered (note you don't see any metal, just plastic insulators, in the photo above) until the connector is seated inside the vehicle's charging port. They also say that conductive chargers are less expensive, and that it is easier to redesign a conductive charger to transfer more power, so as to charge a vehicle's battery pack faster, than it is to do so with an inductive charger; however, the first high-powered quick charger that I've seen put into field testing is an inductive type.

I certainly don't know who's right here; nor is it yet clear, as I said, whether this will be "Beta vs. VHS" where one standard pretty much wipes the other out, or "Windows vs. Macintosh" where one will dominate but the other will survive (after all, I'm still typing this website's code on a Mac). As even the inductive-charger partisans at the EV1 Club note, if the answer were obvious then there wouldn't be any argument! At present, public recharging facilities with both types of connectors are being made available; and, of course, you can install whichever one you want in your own garage! Nonetheless, the California Air Resources Board has recognized that uncertainty over standards has become an impediment to the commercialization of electric vehicles and to the growth of the public recharging infrastructure; thus, as of early 2002, it appears that they are throwing their considerable weight behind the conductive standard. They have found these to be as safe as inductive chargers, and easier to upgrade, as noted above; they also have identified advantages in costs for consumers. They are aiming to get all automakers to adopt a conductive standard by the 2007 model year.

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new 4 July 1998, revised 28 July 2017