When the Audi e-tron battery-electric SUV goes on sale next year, its 432 battery cells will drink from a 150-kw charging firehose–a rate quicker than the Jaguar I-Pace or a Tesla Model S.
The high-energy battery pack, detailed by Audi in Berlin on Wednesday, has an apt, caffeinated analogy built right into its sandwich layer of lithium-ion power. Each battery cell comes in a flexible aluminum-polymer envelope the size of a bag of coffee.
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The 2019 e-tron SUV will be Audi’s first mass-produced electric car, the first of 10 battery-electric cars that the brand will develop and sell in the next few years.
By the time Audi’s planned family of battery-powered vehicles come to market in 2025–in shapes and sizes from compact hatchback to full-size executive car–some 30 percent of Audi’s lineup will be electrified, a promise that’s grown since Audi started down the path to electrification early in the decade.
Audi’s first big battery: the specifics
For its first mass-produced battery-electric pack, Audi designed a flat sandwich of 432 cells that live under the 2019 e-tron’s floor, between its front and rear axles and electric motors. (The e-tron, for reference, sits between the current Q5 and Q7 SUVs in size.) Thirty-five bolts connect the battery box to the body.
The battery pack measures 5.3 feet wide, 13.4 inches high, and 7.5 feet long, roughly the size of a queen bed. The mostly flat pack has a higher section that sits under the e-tron’s rear seat, where Audi packages additional battery capacity. In all, the pack weighs some 715 kg, or more than 1,573 pounds.
In all, there are 36 battery modules in each pack, each about the size of a shoe box. In each module, Audi nestles 12 pouch-style 60-ah (3.5-volt) cells, for a total of 432 cells. Each of those cells is the size of a bag of coffee.
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Audi chose the flexible pouch-type cells over prismatic cells in the e-tron’s pack. Audi engineers say the pouch-type cells may cool a bit better than prismatic cells, which may package better. Otherwise, in cost and complexity, Audi says the cell types compete well on price, and that it will use both types in the future.
Audi has no EPA ratings on range yet, but the 95-kwh pack earns a WLTP test-cycle rating of 400 km, or 248.5 miles.
A set of thermal circuits filled with anti-freeze forms a sort of cooling bed frame for the e-tron battery pack. It’s sealed and thinly sandwiched beneath the pack, not woven between the cells. That prevents more damage should the circuit burst in an accident. Thermal adhesive glues the cooling circuit to the battery pack, and a thermally responsive gel cushions the cells inside the pack.
The pack draws cooling capacity from the air and from the anti-freeze liquid circuit. Under temperate conditions, the e-tron battery pack modulates temperature with air from intakes and a radiator, all guided by electronically controlled louvers that direct airflow. Under more extreme conditions, a chiller acts as a heat exchanger for the cooling circuit. It maintains battery temperatures of 77 to 95 degrees so the battery can be fast-charged repeatedly and quickly at a higher rate. The e-tron battery pack can only maintain those temperatures when the vehicle is in use, or when it’s plugged in for charging.