Explained: Why the 2016 Toyota Mirai, Honda FCV Concept, Have CHAdeMO Sockets on Them

Yesterday, Japanese automakers Toyota and Honda both unveiled their latest hydrogen fuel cell sedans, with the official pre-LA Auto Show press events for the production-ready 2016 Toyota Mirai fuel cell sedan and the 2014 Honda FCV Concept car.

Behind the small panel in the upper-left corner of the Toyota Mirai's trunk is a CHAdeMO DC connector. But what is it for?

Behind the small panel in the upper-left corner of the Toyota Mirai’s trunk is a CHAdeMO DC connector. But what is it for?

On paper, the two cars serve a similar function in the automotive world. Both offer seating for four, a range of around 300 miles per fill of their hydrogen tanks, feature the latest high-pressure, energy dense hydrogen fuel cell stack technology and have similar performance figures.

They also both come with something that has many plug-in car fans scratching their heads in disbelief: built-in CHAdeMO DC sockets.

Usually found on cars like the 2015 Nissan LEAF electric car and 2015 Kia Soul EV, CHAdeMO sockets have traditionally been used to connect fully electric or plug-in hybrid cars to CHAdeMO DC quick charge stations. Designed to refill the car’s battery packs from empty to 80 percent full in around 30 minutes, CHAdeMO DC sockets bypass a car’s on-board charger and pump high current, high voltage power direct into a car’s battery pack.

But while both the Toyota Mirai and the Honda FCV Concept have small on-board traction battery packs to store energy recaptured during regenerative braking and excess power generated by the on-board fuel cell stack, neither battery pack is big enough to make use of the high-power charging current normally used in DC quick charging stations.

The Toyota Mirai Fuel Cell Sedan can use this CHAdeMO socket to provide emergency power when required.

The Toyota Mirai Fuel Cell Sedan can use this CHAdeMO socket to provide emergency power when required.

So if the sockets aren’t use for charging, what are they used for?

The answer is plain and simple: emergency power generation.

In both cases, the Toyota Mirai and Honda FCV concept can be used as emergency power generators, combining the compressed hydrogen in their fuel tanks with oxygen in the air in their hydrogen fuel cell stacks to produce water and electricity at a rate of up to 100 kilowatts of instantaneous power.

During normal operation, that energy is fed directly to the car’s electric motor to provide motive power. But when stationary, both cars can be put into a special emergency power mode, feeding any power generated at the fuel cells directly to an external power inverter connected to the CHAdeMO DC socket.

Like a DC quick charger in reverse — or Nissan’s LEAF-to-Home two-way charging station and emergency back-up generator — the DC power flows from the CHAdeMO socket onto the car into the emergency backup generator, where it is converted back into alternating current at the correct mains voltage for the country the car is in.

Unlike the Nissan LEAF, whose on-board battery pack can be used to power a backup generator for the length of time it takes for its 24 kilowatt-hour battery pack to be depleted, the 5 kilograms worth of compressed hydrogen found in the Toyota Mirai and Honda FCV Concept equate to around 200 60 kilowatt-hours worth of electricity.

Honda's FCV Concept -- also debuted yesterday -- features a CHAdeMO socket for the same purpose.

Honda’s FCV Concept — also debuted yesterday — features a CHAdeMO socket for the same purpose.

That means either car could theoretically power an average home for up to seven days using an appropriate equipped backup power-station, provided of course they had a full tank of compressed hydrogen to start with.

The presence of CHAdeMO sockets on both cars also explains why Honda’s Power Generator Concept — a small external inverter unveiled yesterday which is about the same size as a small internal combustion generator — also has a CHAdeMO connector on it. Small and portable, it can draw up to 9 kilowatts form the Honda FCV concept via its CHAdeMO socket to provide emergency power when and wherever it’s needed.

Sadly however, the feature is one-way only: you can’t use the CHAdeMO socket to recharge either vehicle’s tiny on-board traction battery pack, and you can’t use it to re-electrolyse water back into oxygen and hydrogen.

The Honda Power Exporter Concept features a CHAdeMO plug, which draws power from the Honda FCV Concept and turns it into mains electricity.

The Honda Power Exporter Concept features a CHAdeMO plug, which draws power from the Honda FCV Concept and turns it into mains electricity.

This feature, while unlikely to be of much use in certain future Hydrogen fuel cell markets, is a unique added bonus feature for those who live in areas where earthquakes and other natural disasters are common, like remote parts of Japan or more rural areas of the U.S.

Of course, that particular feature is only possible in more remote areas if there’s somewhere to refill the hydrogen fuel cell vehicle in the first place, something that’s a completely different type of challenge.

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  • So, what happens when someone tries to plug a CHAdeMO quick charger into this plug? 😯

    • It rejects it. Simple as that. The port isn’t a dumb port, it negotiates everything (including the direction of power flow!) with the attached device. In this case, a quick charger would just say “How cute! You can now unplug the cable and vacate this parking spot for someone ahead of you that actually needs it”. Well, in reality, it’d probably say “ERROR” of some kind, though that message would sure be a bonus. It wouldn’t affect the car or the station at all.

      • The irony is if this car had a bigger battery pack, it would be far more efficient, cost far less to run, go just as far – and it could also be an emergency power supply.

        • SSShhhhh!!!!nnnDon’t let the general public know, because if the public start asking for it Toyota would need to provide it unlike the BEV no one is asking them for!!

        • SaturnV

          And put the chademo port outside and recharge the battery. ….

  • Joseph Dubeau

    Could Toyota Mirai recharge a Nissan Leaf?

    • Don’t see why not. Simply plug the LEAF in at the other side of the optional inverter. Or buy the Honda power device pictured above.

      • lee colleton

        There may be a way to engineer a cable with CHAdeMO plugs at either end. Might require some hacking to initiate and control the charge.

        • Engineering the cable plugs is the easy bit. It’s handling the protocols that will trip up such a scheme. There would need to be logic embedded into the cable to make one of the LEAF’s act like an EVSE and adjust its output in sync with the requests from the other LEAF.nTesla sell a CHAdeMo to Tesla adapter cable with such technology on board for about $800. It isn’t a cheap proposition. May as well buy the inverter and be done with it.

  • And, thus begins the race to build the FCEV-to-Leaf charging bridge. I’d imagine tow companies would be wise to buy a few of these to roll out to Nissan’s tow calls, to quick-charge that rare dead Leaf instead of flatbedding it.nnI guess this does serve an unexpected useful purpose for the otherwise-pointless hydrogen cars Toyota’s rushing to get to market now. Few people would have a reason to buy a FCV instead of a pure EV, but these would be useful for those rare occasions…

  • Surya

    Wait a minute. 200 kWh of energy from 5Kg of h2. And it travels 300 miles with that power? A Model S, hardly the most efficient EV, does the same distance on an 85kWh battery! How does that work?

    • The article isn’t clear if the Hydrogen represents 200 kWh of potential energy or actual output from the Fuel Cell. If it’s output from the fuel cell then something doesn’t add up.

    • Found another article. It’s 60kWh of total energy outputnnhttp://insideevs.com/toyota-mirai-fuel-cell-sedan-priced-at-57500-specs-videos/

      • Surya

        300 miles on 60kWh with a car that weighs about the same as a Model S? I’m skeptical.

  • Matt Beard

    And what happens when you plug one of these Honda units into a Leaf, or even an Outlander PHEV?

    • In theory it should work as an inverter. Not sure if the vehicles come with power export activated in all markets or not. Just because the Mirai comes with the connector doesn’t mean it will work with any degree of certainty. One would hope this works for all vehicles but OEMs do odd stuff sometimes.

  • Esl1999 .

    I’m starting to agree with the idea for Japan to go this route for their cars. They tend to buy small cars which restricts the amount of batteries that can be fitted inside them. After the 2011 Tohoku Great Quake, the need for emergency power is going to be of greater concern for the populous. For Japan, this might be worth the added cost and energy inefficiency. There is a place for FC transport (mainly in much larger forms of transport), but FC cars in other parts of the world may not be needed.

  • Guest

    A bit off topic, but this is really expensive car that can’t take road trips outside of California. Or what about Japan? What kind of hydrogen infrastructure do they have? Or their plans? This seems pretty silly, no?

  • ggerke

    A bit off topic, but this is a really expensive car that can’t take road trips outside of California. Or what about Japan? What kind of hydrogen infrastructure do they have? O their plans? This seems pretty sill, no?

  • Kenneth_Brown

    The best engineering reason to have a battery pack in an FCV vehicle is to be able to use a FC that doesn’t need to provide the peak energy needed to accelerate the car from a standing start. Once you’re up to highway speeds, it doesn’t take a lot of power to maintain it so the FC can recharge the battery. Fuel cells appropriate for passenger cars tend to use more exotic and expensive materials to keep the weight down. The smaller the cell they can fit, the better the sticker price. nnnWhat do you do if you have been using your car to power your house and discover that you’ve run the H2 tank dry? Flat bed the car to the nearest refueling station (20 miles away) or hope that AA adds a Hydrogen delivery service that doesn’t cost too much?