With diesel engines in the doghouse in Europe in
general—and within the Volkswagen Group in particular—electric vehicles are about
to go front and center on the Continent.
For its part, Audi will start its electrification push in earnest with the e-tron Quattro, an
all-electric SUV sized and priced roughly between the Q5 and Q7 models; it debuted as
a prototype last month at the Geneva auto show.
It will hit our shores in early 2019 and will be the first of three Audi electric models
by 2020, with several more expected by 2025.
Anticipating this onslaught of electric models and understanding that the transition to electric
propulsion involves more than the vehicle itself, Audi, along with its electric partners,
has put some thought into making electric charging easier and more accessible.
The company invited us to Germany to show us what it is planning.
But let's start with the car.
Looking sleek and elegant—the prototype is pictured directly above, and a concept
version is shown at the top of this post—the e-tron is a low-ish SUV at 60.7 inches tall,
and it stretches 192.1 inches long and is 76.0 inches wide.
Inside, it will seat five in two rows of seats, and it will probably introduce a curved OLED
display for the key readouts and functions in front of the driver.
The concept is powered by three electric motors developing a total of about 430 horsepower,
with an additional 66 horsepower available for short bursts.
The three motors are arranged with one in front driving the front wheels through a conventional
differential and two in the rear, one per wheel.
This makes torque vectoring very easy to implement to improve handling and responsiveness.
By the way, in much the same way that the engine is the heart of a conventional car,
Audi views the electric motors and the power-control electronics to be the heart of an electric
car, so it is keeping the design and manufacturing of these parts in-house.
Although this electric machine is likely to be heavy, as are all machines of its ilk,
there should be enough power to accelerate from zero to 60 mph in the mid-four-second
range.
The production version of the e-tron will be introduced later in 2018 for Europe, and
we expect it to arrive in the United States in the first quarter of 2019.
The e-tron promises a maximum range of 248 miles using the new WLTP driving test cycle,
which, unlike the previous—and highly optimistic—NEDC European driving cycle, is said to be real-world
realistic.
With its three-motor drive, achieving that range requires a 95-kWh battery.
The battery consists of 36 shoebox-sized modules, each housing 12 lithium-ion cells.
The cells are either LG Chem pouch units, which are long, thin, and arrayed lengthwise
in the modules, or Samsung prismatic cells, which are shorter, thicker, and oriented crosswise.
Both types of cells develop 3.5 volts and have a capacity of 60 ampere-hours.
Audi thinks it's important to have at least two suppliers for reliable delivery, to foster
technical competition, and to have cost comparison.
The 36 modules are stacked in two levels, with 31 in the main level and five more in
a second level beneath the rear seat.
Audi states that the battery operates at a nominal 400 volts, so the most likely arrangement
is for the battery to be designed with the cells in each module wired in series and strings
of nine modules also wired in series.
Then the four strings of nine modules are connected in parallel.
Operating at the correct temperature is critical to a long and happy battery life, particularly
when there's lots of electricity flowing into or out of the battery.
Audi says that the e-tron's battery operates best between 77 and 95 degrees and uses a
liquid cooling system to maintain that temperature range.
This system consists of a manifold fitted to the bottom of the battery assembly, with
the fluid—a mix of water and antifreeze—entering the left side and returning on the right.
Between these two main passages are a series of flat tubes running crosswise underneath
the battery.
When the battery is not running too hot or the outside temperature isn't very warm,
the cooling fluid is simply circulated through a radiator in the e-tron's nose.
However, when more cooling is required, an air-conditioning system cools the fluid to
remove more heat.
The air conditioner can also reverse its operation and become a heat pump to heat the fluid and
warm the battery when necessary.
However, this is only done when the car is connected to a charger.
Heating the battery when the car is unconnected and parked doesn't justify the energy expenditure.
The battery modules are housed in a complex and stout housing that serves both to protect
the battery and to form part of the car's structure.
There's a heavily ribbed cast-aluminum frame that protects the perimeter of the battery.
Within this frame is a gridlike aluminum crash structure that separates the battery modules
and also gives the entire battery assembly great strength.
This framework reinforces the e-tron's passenger cell and provides resistance to penetration
during side-impact crashes.
The battery pack is sealed by a top cover and two bottom covers, one of which separates
the cooling system manifold from the battery and another at the bottom that protects the
battery against stone chips and other external impacts.
Audi engineers think it's very important to make sure that the cooling fluid is physically
separate from the batteries to preclude any possible electrical shorting should the cooling
system spring a leak.
Of course, this means that there are probably several pounds of thermally conductive sealant
between the cooling manifold, the battery tray, and the aluminum module housings to
promote good heat transfer.
The entire assembly is a little bigger than a California Queen mattress—64 by 90 inches,
although with beveled corners and only about six inches thick.
The complete battery assembly weighs about 1550 pounds.
In what is quickly becoming the usual fashion for EVs, the e-tron's charging port is on
the left side, just forward of the driver's door.
The door is power operated, revealing an AC charging port as well as DC terminals for
fast charging.
In Europe, which uses 230-volt wiring across the board, plugging the e-tron into a standard
outlet provides 2.3 kW of power and takes about a day and a half to fully charge the
battery.
Using a 400-volt, three-phase circuit raises the input power to 11 kW, which brings the
charging time down to 8.5 hours.
A second, optional charger can raise that charging power to 22 kW and further reduce
the charging time to 4.5 hours.
In the United States, where our 220-volt wiring can only deliver about 9 kW, expect the charging
time to be more like 10 hours.
And the standard 120-volt outlet, which can only provide about 1.5 kW, drags out the charging
time to two and a half days.
Multi-hour charging is fine when the car is parked for an extended period at home or at
work, but for replenishment during longer drives, a faster charge is required.
Currently, there are various quick-charge options ranging from 50 kW, which provides
an 80 percent charge in 80 minutes, to 100 kW, which does an 80 percent charge in 40
minutes.
These are 80 percent charges because the battery requires lower current when topping off the
battery's final percentage.
Getting that last 20 percent of charge extends the charging times by at least 30 minutes.
The e-tron is also designed to accommodate a 400-volt, 150-kW charge, which achieves
an 80 percent charge in only 30 minutes.
And there is talk of a 350-kW charger that can do it in 12 minutes.
Those are impressive times, but keep in mind that 80 percent capacity is only about 200
miles of range—or roughly half what a typical gas tank can provide in a conventionally powered
vehicle.
So even a 30-minute fast charge pales in comparison with a five-minute-long, 400-mile gas-tank
fill-up.
In Europe, there are currently some 89,000 charging points, with some 2000 of those being
high-speed chargers.
But they belong to hundreds of different organizations and operators.
Audi, in partnership with several other European auto manufacturers, plans to organize this
polyglot charging system with something called the Ionity network.
It promises to make it easy to purchase electricity from any of these chargers, while also rationalizing
the charging plugs and building more high-powered fast chargers.
Using this network, an app in the car or on your phone can be used to navigate to any
given destination while also keeping track of the e-tron's battery state of charge,
the location of the various charging stations, and the price of the electricity, so users
can most efficiently and economically integrate charging stops into their trips.
It will even consider whether the various charge points are occupied, helping to minimize
charging delays.
In the United States, the VW Group is setting up a similar network of charging stations,
called Electrify America.
For now, Electrify America has far fewer charging stations than the Ionity network, but the
plan is to have hundreds of 150-kW and 350-kW chargers in place by 2019, including at 100
Walmart locations by mid-2019.
Buying gas is easy.
The price is posted, and that's what you pay.
Electricity, not so much.
The reality is that charging stations are expensive to set up and install, and they
get more expensive as their charging power increases.
Plus, time is money, so it is expected that a charge at a fast-charging station will cost
more than a charge at a slower one, even though the amount of electricity pumped into your
battery is the same.
Furthermore, there is demand-based pricing for electricity in many parts of Europe—and
even in parts of the United States.
There, buying electricity during the heat of the day, when factories and air conditioners
are humming and creating high power demand, can be more expensive than buying the same
amount of electricity after midnight, when demand is low.
This means that it's wise to charge at home and take advantage of the car's programming
and scheduling abilities to begin charging when prices dip.
But it also means that if you are taking a long drive and using fast chargers in the
middle of the day, your trip might be more expensive than you anticipated.
For many, paying $2.50 a gallon, whether you pump it quickly or slowly, at any time of
the day or night, will continue to seem like a pretty good deal.
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