Here's why the Porsche Mission E charges into the future with 8000-volt technology

2018-02-16 - Car and Driver (caranddriver.com) Blog post article by Bengt Halvorson - February 15, 2018
The Porsche Mission E will charge its battery pack, Porsche promises, in half the time it takes present-day Tesla vehicles, which are the charge-rate champions now. Porsche certainly plans to deliver on the strong and silent straight-line performance that has been Tesla’s longtime YouTube party trick—and to add the sustained hot-lap capability that comes with the Porsche pedigree and has been missing from Tesla. But when the test-drive gasps subside, it may be its charging performance that will set the Porsche Mission E apart when it arrives late next year.

That speedier charging, which Porsche is calling Turbo Charging—a shot over the bow at Tesla’s Supercharger tech and charging network—is made possible through a key decision made early in the development process. Engineers looked at the sort of charge times they wanted—with a long-term goal to restore a driving range of several hundred miles after only 10 to 15 minutes—and found 50-kW Level 3 speeds and even Tesla’s 120 kW to be unacceptable. With most electric cars’ underpinnings in the 400-volt range, Porsche’s goals simply wouldn’t be possible by the laws of physics. Porsche’s future EVs would be unreasonably limited at the charge port by the resistance (and heat) generated by raising the current high enough to reach the charging-power levels needed.

Porsche has been mindful about engineering in compliance with Combined Charging System (CCS) standards, so you’ll likely be able to charge a Mission E quite quickly with some of the hardware that’s being installed today, such as the many 150-kW chargers being deployed via Electrify America. At present, ABB’s fast chargers can accommodate up to 920 volts, so the capability is there. The 800-volt, 320-kW level that Porsche is using for its own Turbo Chargers helps it get under the 20-minute recharge target, like the 150-kW units, by using actively liquid-cooled cables. Porsche’s station layout saves space by using one large cooling reservoir for a bank of many chargers at a station—a move that’s still under debate, because some hardware makers think the chargers will be more reliable if they each draw from their own reservoir.

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