Audi Unveils Plug-In A7 Sportback h-tron Quattro At 2014 LA Auto Show

NOV 24 2014 BY MARK KANE 25

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi unveiled at the 2014 Los Angeles Auto Show the A7 Sportback h-tron, a concept fuel cell powered car.

But this one is more interesting, as this is a plug-in fuel cell vehicle, with an AC charging inlet. 2 hours is the time it takes for full recharge of the 8.8 kWh battery pack – up to 31 miles (50 kilometers).

And this is, of course, a lithium-ion battery pack (not NiMH like in the case of Toyota Mirai).

Audi is using four hydrogen tanks for over 310 miles of range (500 km).

Performance with double motor (one per axle) stands at 7.8 seconds from 0 to 60 mph. Top speed is 130 mph.

Each motor can deliver 85 kW or 114 kW (if the voltage is temporarily raised) and has peak torque of 270 Nm.

According to Audi, the fuel cell achieves efficiency of as high as 60 percent, but operates across a temperature range of 80 degrees Celsius and demands more cooling than an equivalent combustion engine.

“It covers over 500 kilometers (310.7 mi) on one tank of fuel – and its exhaust emits nothing more than a few drops of water: The A7 Sportback h tron quattro uses a powerful, sporty electric drive with a fuel cell as its energy source, in combination with a hybrid battery and an additional electric motor in the rear. Its drive configuration makes the emission-free Audi A7 Sportback h-tron quattro a quattro through and through, with 170 kilowatts of power at its disposal – a new departure in fuel cell cars. There is no mechanical connection between the front and rear axles. As an e quattro, the A7 Sportback h-tron quattro features fully electronic management of torque distribution.”

“In the fuel cell mode, the A7 Sportback h-tron quattro needs only about one kilogram (2.2 lb) of hydrogen to cover 100 kilometers (62.1 mi) – its energy content is equivalent to that of 3.7 liters (1.0 US gal) of gasoline. The tank capacity means it is capable of a range of more than 500 kilometers (310.7 mi).”

“Like a car with combustion engine, refueling takes no more than around three minutes. The range is boosted by up to 50 kilometers (31.1 mi) by a battery with a capacity of 8.8 kilowatt hours, which is recharged by recuperation or alternatively from a power socket. As a plug-in hybrid, the A7 Sportback h-tron quattro will thus have crucial extra range in reserve.”

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

 “The Audi A7 Sportback h-tron quattro

It sprints from 0 to 100 km/h (62.1 mi) in 7.9 seconds and on to a top speed of 180 km/h (111.8 mph). It covers over 500 kilometers (310.7 mi) on one tank of fuel – and its exhaust emits nothing more than a few drops of water: The A7 Sportback h-tron quattro, which Audi is unveiling at the Los Angeles Auto Show 2014, uses a powerful, sporty electric drive with a fuel cell as its energy source that operates in combination with a hybrid battery and an additional electric motor in the rear. The overall electrical system power of 170 kW is transferred to both the front and the rear wheels. This drive configuration makes the emission-free Audi A7 Sportback* a quattro through and through – a new departure in fuel cell cars.

“The A7 Sportback h-tron quattro is a genuine Audi – at once sporty and efficient. Conceived as an e-quattro, its two electric motors drive all four wheels,” explained Prof. Dr. Ulrich Hackenberg, Member of the Board of Management for Technical Development at Audi. “The h-tron concept car shows that we have mastered fuel cell technology. We are in a position to launch the production process as soon as the market and infrastructure are ready.”

The “h” in the name h-tron denotes the chemical element hydrogen. In visual terms the technology demonstrators that Audi has brought along to the Los Angeles Auto Show basically resemble the production models. As the label with the h-tron signet reveals, this concept car now takes its place alongside the other Audi models with alternative drive principles, the e-tron and g-tron. Externally, there is no other evidence of the fuel cell that converts hydrogen into electrical power on board the vehicle.

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

The fuel cell

The crucial differences are beneath the hood of the A7 Sportback: The fuel cell in the Audi technology demonstrator is installed at the front, mirroring the conventional A7 Sportback with combustion engine. Because the exhaust system only has to handle water vapor, it is made of weight-saving plastic.

The fuel cell itself comprises over 300 individual cells that together form a stack. The core of each of these individual cells is a polymer membrane. There is a platinum-based catalyst on both sides of the membrane.

This is how the fuel cell works: Hydrogen is supplied to the anode, where it is broken down into protons and electrons. The protons migrate through the membrane to the cathode, where they react with the oxygen present in air to form water vapor. Meanwhile, outside the stack the electrons supply the electrical power – depending on load point, the individual cell voltage is 0.6 to 0.8 volts.

The entire fuel cell operates in the voltage range of 230 to 360 volts. The main auxiliary assemblies include a turbocharger that forces the air into the cells, the so-called recirculation fan – it returns unused hydrogen to the anode, thus increasing efficiency, and a coolant pump. These components have a high-voltage electric drive and are powered by the fuel cell.

There is a separate cooling circuit for the essential cooling of the fuel cell. A heat exchanger and a thermoelectric, self-regulating auxiliary heating element maintain pleasant temperatures in the cabin.

The fuel cell, which operates across a temperature range of 80 degrees Celsius, places higher demands on the vehicle cooling than an equivalent combustion engine but achieves superior efficiency of as high as 60 percent – almost double that of a conventional combustion engine. Its cold-starting performance is guaranteed down to -28 degrees Celsius.

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Plug-in hybrid

A special feature of the A7 Sportback h-tron quattro is its plug-in hybrid concept – this represents a logical evolution from the Audi A2 H2 and Q5 HFC test cars. It has a lithium-ion battery on board that can be recharged from the power socket by lead; with an 8.8 kWh energy capacity, it has been adopted from the A3 Sportback e-tron*. It is located beneath the trunk and has a separate cooling circuit for thermal management.

This high-performance battery makes the ideal partner to the fuel cell. It can store energy recovered from brake applications and supply considerable power for full-load boosting. This paves the way for impressive acceleration, making the A7 Sportback h-tron quattro truly live up to quattro standards. Both the front and rear axles have no mechanical connections for the transmission of power. In the event of slip, the torque for both driven axles can be controlled electronically and adjusted continuously.

On battery power, the Audi A7 Sportback h-tron quattro covers as much as 50 kilometers (31.1 mi). The battery in the rear of the plug-in hybrid can be recharged by lead. Depending on the voltage and current rating, a full recharge takes between two hours (industrial power socket/360 volts) and four hours (domestic power socket at 230 volts).

The battery operates at a different voltage level to the fuel cell. For that reason, there is a DC converter (DC/AC) between the two components. This tri-port converter is located behind the stack. In many operating statuses it equalizes the voltage, enabling the electric motors to operate at their maximum efficiency of 95 percent.

The power electronics in the front and rear of the vehicle convert the direct current from the fuel cell and battery into alternating current for the electric motors to drive the front and rear axles separately.

The two electric motors, which are cooled by a low-temperature circuit together with the voltage converters, are permanently excited synchronous machines. Each of them has an output of 85 kW, or even 114 kW if the voltage is temporarily raised. The peak torque is 270 Newtonmeters (199.1 lb-ft) per electric motor.

The electric motors’ housings incorporate planetary gear trains with a single transmission ratio of 7.6:1. A mechanical parking lock and a differential function round off the system.

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

The appeal of e-quattro

Driving in the Audi A7 Sportback h-tron quattro offers the full appeal of electric drive in conjunction with the new e-quattro. The silent propulsion is fully available from the off, and the fuel cell reaches its maximum output within one second at full load – a more dynamic response than a combustion engine because the entire drive system involves only a few mechanical components.

With 540 Nm (398.3 lb-ft) of propulsive power at its disposal the Audi A7 Sportback h-tron quattro, which tips the scales at only around 1,950 kilograms (4,299.0 lb), races from a standstill to 100 km/h (62.1 mph) in 7.9 seconds. Its top speed is 180 km/h (111.8 mph) – a top figure for its field of competitors. The e-quattro concept requires precise coordination of the electric motors – the technology demonstrator offers a sporty, stable and high-traction drive that is comparable to a production car with mechanical quattro drive.

A power meter – in the place of the revolution counter in the instrument cluster – informs the driver of the momentary power flow. The outer sections show the fuel level in the hydrogen tank and the level of battery charge. Graphics on the MMI monitor visualize the energy flow. When the driver presses the EV button, the technology demonstrator drives solely on battery power.

Switching from automatic transmission mode D to S increases the level of energy recovery when braking, so that the battery is charged up effectively during sporty driving. Brake applications, too, are almost always accomplished fully electrically: The electric motors then act as alternators and convert the car’s kinetic energy into electrical energy that is stored in the battery. The four disk brakes only become involved if more forceful or emergency braking is required.

The tank flap is in the right side section of the five-door coupé, concealing a filler connector for the hydrogen. Fully refueling with H2 takes around three minutes, roughly as the same as a conventional automobile. The tanks communicate with the refueling system by infrared interface and equalize the pressure and temperature levels.

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Zero emissions

The four hydrogen tanks of the Audi A7 Sportback h-tron quattro are located beneath the base of the trunk, in front of the rear axle, in the center tunnel. An outer skin made from carbon fiber reinforced polymer (CFRP) encases the inner aluminum shell. The tanks can store around five kilograms of hydrogen at a pressure of 700 bar – enough to drive over 500 kilometers (310.7 mi). According to the NEDC cycle, fuel consumption is roughly one kilogram (2.2 lb) of hydrogen per 100 kilometers (62.1 mi) – an amount with an energy content equivalent to 3.7 liters (1.0 US gal) of gasoline.

It is already the case that the A7 Sportback h-tron quattro always travels with zero local emissions. By using the renewable fuel hydrogen, it can also be used globally as a zero emissions vehicle: Since 2013 Audi has been operating a pilot plant in which renewable wind power is used to produce hydrogen by electrolysis. At present, this hydrogen is still used in an additional production process to obtain synthetic methane (Audi e-gas). A future move to feed this hydrogen into a hydrogen supply and filling station network would make it available for refueling fuel-cell vehicles. This is a sound option for sustainable mobility with no emissions.”

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

Audi A7 Sportback h-tron

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25 Comments on "Audi Unveils Plug-In A7 Sportback h-tron Quattro At 2014 LA Auto Show"

newest oldest most voted
AddLightness

A plug-in FCEV is a very tempting design. All electric daily driving where you can recharge at home cheaply and then a hydrogen range extender for the occasional mid/long distance trip. It’s tough to say whether I would rather have a huge 300 mile battery to lug around everyday unused and then have short yet longer than ideal recharge times when traveling or a more complex and less efficient hydrogen range extending system that I have to pay carbon-based energy companies to refuel in marginally less time. I think battery technology will eventually provide the density and recharging speed at a cost that will make it the superior option pricewise and design-wise.

Brian

I agree. If battery improvements don’t come as quickly as many expect in the next decade or so, I would find this to be a decent compromise for finally getting off gasoline completely. If it was affordable and hydrogen were available (two huge IFs, I know), I would prefer this over a gasoline PHEV/EREV.

Sivad

Yes batteries are heavy but there is always an assumption by everyone that FCVs are much lighter and it turns out this isn’t true. Compare the Tesla S85 with a curb weight of 4,700 lbs with the much smaller compact Mirai with a curb weight of 4,080 lbs. For comparison the heaviest midsized Camry has a curb weight of 3,400 pounds with an output of 268hp. And if you take into account the Mirai’s 152 hp output compared to the S85P’s 416 hp or the P85D’s 690 hp the weight to power output is actually in the BEV’s favor.

Mint

Well, at least there’s a concept now for the mythical FCPHEV. That’s a LOT of trunk space being lost to implement it. It’s not gonna do well against a Model S or even a regular A7 PHEV.

Let’s see if Audi actually builds it.

MDEV

Just imagine the maintenance of this mix of technologies, a real nightmare for the owner cost.

Micke Larsson

What maintenance? There is no reason why a car like this shouldn’t be basically maintenance free.
And definitely nowhere near an current ICE.

JakeY

The additional thing the fuel cell has is an air intake and water exhaust, so presumably the air filter will have to be changed. Also if hydrogen tanks are anything like CNG tanks, they have to be inspected every 3 years. So far from maintenance free, although better than an ICE.

Mint

Complexity is the same as a regular FCV. The battery is just bigger, and a simple charger is added.

MTN Ranger

No thanks, I’d rather have an e-tron than an h-tron.

Micke Larsson

Most interesting will be to see
1. if they produce it in more than a marginal number
2. if they can get the price down to compete with a regular PHEV.

I’d prefer a larger battery to be able to all daily driving on plugged electric, but this solution is way superior to non-pluggable fuel cell cars.

David Murray

this is the most logical and practical FCEV I’ve seen so far. Hydrogen for range-extender is the only application that makes sense. The only trouble is that the all-electric range is a bit too short for most people to complete their daily commute on battery power. That’s where a vehicle like this would shine is for all-electric daily driving and using the hydrogen for long trips only. They should shoot for 40 miles AER.

QCO

Agreed, the more practical use of fuel cells is for range extension. Much more logical than Mirai, although this implementation looks overly complicated and expensive to produce.

I like Winterkorn’s comment about the VW FCV, which presumably uses the same technology. He said we can build one and here it is, but there’s no point to putting it in production because there are no H2 filling stations. (stunning insight, eh?!)

This is only a halo demonstration vehicle.

Mint

It’s logical only if you ignore economics and PHEV competition. Who’s gonna pay such a large premium, lose so much trunk space, and also lose performance for just a few more green miles?

Yes, the PHEV A6/A8 will be much faster than 7.8s 0-60.

Pete Repete

Looks great, but if 2 motors and individual driven axles are your thing – I’d suggest a P85D. I’d think an eventual production A7 h-tron would set you back a lot more than the Tesla, so I know which one I’d take – I really don’t have a problem with the charging time.. Make that a P85D with an Audi interior though…

pjwood

If they could just get the battery down to 4kwh, this thing would charge twice as fast!

Mike I

I don’t know whether to laugh or cry at this comment.

QCO

I guess Toyota took that thought further and made the battery so small you don’t have to plug it in at all!

Tesla Fan

all audis look boring, even the A7

Brian

You should change your name to “Tesla Fanboy”

Blueberry Blipblop

Doesn’t the Audi A7 look alot like the Tesla Model S? Which car came first?

And a general question about FCV’s. We know that a Tesla Model S’s original battery probably could last the car’s lifetime, if you accept about 10% less range. And in eight years or so you could probably buy a new battery that is 50 percent bigger for a decent price for the Model S. Now to the actual question.

What lifetime can we expect from the fuelcell drivetrain, including the tanks?

From what I have understood the tanks cannot last very long (how long?), since the hydrogen is taking it’s toll on them pretty hard making them brittle.

Bill Howland

Exactly… What is the lifetime and replacement expense of all the novel perishable components? Is it strictly a miles driven aging, or does just the plain passage of time wear things out?

Too bad these articles never seem to mention the practical stuff.

Stephen

That’s a lot of tank space. How much battery could they pack in instead. I am also unneasy about sticking those tanks out behind the rear waiting for a rear end collision. How would an e- tron compare?

Scramjett

Make the EV range around 60 – 90 miles and this could be appealing.

Jouni Valkonen

In the premium category of Audi A7, I think that the electric range should be around 300 miles. Possibly 400. 60 to 90 miles is something what you could expect from small city car.

Blueberry Blipblop
Maybe both Elon and Toyota are right.. Hear me out on this one. This hybrid concept that Audi has with an electric plug-in ability plus fuel cell could end up being a good contestant against plain EV’s in the next decade or so. I think the battery needs to be abit bigger than 9-ish kWh, more like Volt size 15-20 kWh plus the 300 mile range hydrogen tanks. That would mean most people would drive the car on electricity alone in their daily commute, and for long distance travel there will be a few hydrogen stations, just like Tesla’s supercharger network are today, where you could fill it up quite fast. This setup will solve alot of problems. First, the expensive to build hydrogen stations don’t have to replace every gas station out there since hydrogen will only be used occationally on long trips. So you won’t need that many hydrogen stations. And when you use hydrogen the refilling time is like filling up gas, or just some minute longer. The problem will we see in the near future with plain EV’s is that the Superchargers/Fast DC chargers will be crowded since you need atleast 30 minutes for a recharge.… Read more »