The battery in an electric car is huge — often several times the capacity of a home storage battery. For most of its life that battery just sits in a driveway doing nothing. Bidirectional charging is the idea that it should not. A 2022 Enel X Way patent shows the hardware that makes a car's battery flow both ways.
Ordinary charging is one-directional: grid power flows into the car. Bidirectional charging adds the reverse path — the car can push power back out, into your home during an outage (vehicle-to-home) or onto the grid when it is stressed and prices are high (vehicle-to-grid). The mechanism requires power electronics that can run in both directions and, critically, that can do so safely and in sync with the grid's voltage and frequency.
Enel X Way's grant US11498448B2, "High power bidirectional grid connected charger with split battery architecture," tackles the high-power version of this. The 'split battery' detail is the interesting engineering: dividing the system lets it handle high power flows in both directions more flexibly. The charger is no longer a one-way funnel; it is a two-way interface between a giant mobile battery and the grid.
Why the arithmetic is staggering: a single EV might store enough to run a house for a day or two. Multiply by millions of vehicles, most of them parked at any given moment, and the parked fleet becomes one of the largest potential storage resources imaginable — capacity that already exists, bought and paid for as transportation. Bidirectional charging is the key that unlocks it.
The honest brakes: two-way charging stresses the battery, raising warranty and degradation questions; it requires utility approval and interconnection rules that are still maturing; and it needs the car, the charger, and the grid operator to all speak the same protocol. A 2022 patent on the charger hardware is one necessary piece, not the whole system. But it is the piece that proves the physical interface is buildable — the rest is contracts and software.