Receptacle Roundup VIII: CHAdeMO

Here we g-g-g-go: a standard not only designed for cars, but designed to be… awesome for cars.  Is it?









The CHAdeMO connector and protocol comes from a board containing Nissan, Mitsubishi, and the utility TEPCO (Tokyo Electric Power Co.).  Toyota and Subaru (via its parent, Fuji Heavy Industries) are officially partners, but have not backed that up with any compatible EVs in North America; Zero Motorcycles is about to release products but appears to have second-class citizenship.  On the fixed end, charger units are already being built and installed from Fuji, AeroVironment, Eaton, and others.  If that sounds like fairly-solid support, it is: in the Japanese market, there are well over a thousand installations.  Other markets have hundreds, too.

So, what’s in it for me?  This standard gives DC power, not AC; batteries like that.  Using DC, an EV battery pack can be given its native voltage (over 400V, called “Level 3“), and brutal currents (well over 100 amps).  Power, then, is many tens of kilowatts, possibly 90 kW.  This means charge times as low as 30 minutes, from fully-depleted to 80%.  BIG deal- this is now something you’d do on a road trip, while having a handy lunch, or possibly a stretch and a long bathroom break.  CHAdeMO is a corruption of “charge and move,” while supposedly being a pun on “o cha demo ikaga desuka”- Japanese, I’m told, for “let’s have tea while charging.”  Not a meal, not a sleep- a cup of tea.

That’s right, folks: a 30-minute vehicle charge… sort of; I need to qualify that.  First, the charger (and this one’s really a charger) will stop at the 80% mark.  Lithium-based batteries are vulnerable to overcharging, and must not cross 100%.  Most chargers then slow down as they approach “full.”  When you have charging rates this high, the CHAdeMO protocol will slow down, then stop at 80% to be sure.  Granted, that’s still the equivalent of 36 minutes for a literal “fillup”- still miles ahead of any connector I’ve posted here so far.  By comparison, the next level (J1772 at its max 80A, called “Level 2“) would deliver ~20 kW.  And that’s on paper- no real-world J-installations, and few cars on the road today, will actually reach that.

Second, these high power levels are not without drawbacks.  Running current through consumer gear causes heat.  Running these ferocious currents causes major battery-pack heating.  Lithium chemistries are not to be overheated; doing that shortens their lives.  So far, carmakers recommend no more than one CHAdeMO stop per day, to allow heat to dissipate.  If ambient temperatures are already high, and/or you’ve been running hard, even that one may not be the best recommendation.

(Of course, the prime customer for CHAdeMO is the Nissan Leaf, the same vehicle that went with air cooling for its large pack.  No word on Zero’s stance; I don’t believe the Zero battery packs will be liquid-cooled, and they might not even have an air circuit.  Hence, Zero is so far promising 1-hour recharges to 80%, not half-hour.)

How does a CHAdeMO unit charge so fast?  I touched on this previously.  Chargers for AC electricity are actually in the vehicle.  Grid AC is fed to that onboard charger, which converts it to DC at the needed voltage for the pack’s sake.  By comparison, a high-powered DC supply at the curb delivers its power directly to the pack, bypassing any onboard chargers.  CHAdeMO, then, is an actual charger, like the external brick for a modern laptop, or the wall wart for a modern cell phone.  Once that DC charger is out of the vehicle, it can be big and heavy, with its own surface area, heat sinks, and fans; that’s how it can handle these massive loads.  The vehicle instead does housekeeping functions and the initial connection.

Okay, so the big, powerful unit’s now out of the vehicle and on the curb- how does that part work?  Unfortunately in this case, our power grid delivers AC, not DC.  And most grid customers get 240V service; the packs in most plug-in vehicles operate at 300-400V or so.  Level 3 must install a 3-phase line to the grid, like an industrial site, to get 440-480V power.  The job of the CHAdeMO unit, then, is mainly to rectify that high-voltage AC to DC.  It also performs minor functions, like initialization at hookup (autonegotiations and/or “handshake”), any billing or membership data, and safety disconnects.  Like J1772, an unused connector is electrically dead as a safety feature, and won’t really turn live until a proper hookup has been signaled.  A hookup with no fingers inside, and insufficient rainwater.

Also like J1772, the actual pins are shrouded with plastic.  Even if the connectors were live, there are few scenarios where a finger, key, etc. could get inside and draw dangerous current.  This system was designed in Japan, a rainy country.  Mass shockings have not occurred there, in the few years of public usage so far.

So what has happened?  On one hand, the user reports (at least, in North America) include a worrying fraction of units down.  To be fair, some of this is due to the Blink network having lousy service and reliability in general; this is also true of their J1772 locations.  But the CHAdeMO connector is large, heavy, and complex, with not three pins, but ten.  Yes, ten.  Two huge connectors for main power, and the rest for handshaking and other negotiations.  A latch on the outside then secures the coupling.  This design turned out to be a bit finicky in practice; new, untrained operators may be resorting to force, breaking the connectors.  From my point of view, I’m not sure how much of the in-service record is due to bad Blink service, ham-fisted drivers, and/or the inherent design of CHAdeMO.

But, hey, no electrocutions.  This, despite the ferocious 440V or more, which can leap across gaps and insulators that would easily confine Level 2 or 1.  I’ll also point out that this service record includes rainy Seattle, and baking Phoenix.

On the other hand, fast Level 3 is simply a game-changing capability- it redoes the EV use model.  Imagine a city car, with a territory largely set by a predefined action radius, centered on your house.  Adding public charging at low power then gives you some flexibility… but in case of emergency, and in those usage cases where you’ll be parked for hours.  Level 3 power, however, can partially erase the very concept of predefined range.  I’ll compare it to how in-flight refueling turned Air Forces and carrier wings from being mostly tactical support, to global, strategic threats.  Notice I said “partially erase,” though.  CHAdeMO still takes half an hour, and that’s just to 80%.  Half an hour is still a plan you have to work into your day; it’s not something you just do, just because.  (You also have to come near a CHAdeMO site, of course.)

How is the game, now?  Two groups have completed road trips in pure-EV, CHAdeMO vehicles.  One team of Nissan Leafs and Mitsubishi i’s crossed the mountains of Washington state.  They were celebrating the opening of the CHAdeMO installation at Stevens Pass, allowing battery-only driving down Highway 2.  That’s now central Washington, to the Sound, and down I-5 to Oregon, on battery power.  And since Oregon installed CHAdeMOs, you can then keep going into California.  Another team did the opposite.  Tony Williams and his daughter did a 3-country run- BC2BC (Baja California to British Columbia) in a Leaf.  Unfortunately, the Williamses encountered The Gap.  Central California not only lacks CHAdeMO, but J1772s.  They had to use RV parks and hotel outlets.

That’s the issue with EV infrastructure in general, and Level 3 in particular.  Electricity is found anywhere you “set foot in a civilized system.”  But actually delivering that electricity in a nice, standardized format, and the CHAdeMO standard specifically, costs money…


7 thoughts on “Receptacle Roundup VIII: CHAdeMO

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