For the Friday files, some cool new technology: How about a car that plugs in, but doesn't use that electricity to power the car?

Nope, we're not talking about battery electric cars like the 2011 Nissan Leaf. Or range-extended EVs like the 2011 Chevrolet Volt. Or even conventional hybrids adapted to plug in, like the 2012 Toyota Prius Plug-In Hybrid.

Instead, this is a new concept, revealed in a patent filing from Ford.

The notion is to run a vehicle's electric accessories on power stored in a somewhat larger battery, which would be recharged by plugging it in when the car is parked. The battery wouldn't power the car, just its accessories.

Ford delivers first Escape plug-in hybrid SUV

Ford delivers first Escape plug-in hybrid SUV

As automakers work feverishly to make their engines smaller and more efficient, they're doing everything possible to reduce the load on those engines. Electric accessories--from power steering pumps to air-conditioning compressors--eliminate belt drives that sap power.

Now Ford's concept eliminates the last belt drive: the alternator. Or at least, decouples it for shorter trips.

BMW now has an alternator that engages only on engine overrun, decoupling it via a clutch when power is demanded from the engine. This lets the alternator charge only on "wasted" power.

BMW calls that "rengenerative" charging, in a nod to the regenerative braking in hybrids and electric cars that recaptures brake energy to charge the battery. It's part of the carmaker's Efficient Dynamics suite of fuel-saving technologies.

Porsche lightweight lithium-ion 12-Volt starter battery

Porsche lightweight lithium-ion 12-Volt starter battery

But until now, we're not aware of any proposals to eliminate the alternator altogether and operate those electric accessories solely on grid power stored in the car's battery. Enter the patent Ford has just applied for.

The vehicle would obviously still have to carry an alternator, for long trips in which the battery's stored energy was eventually depleted. But like the range-extending engine in a 2011 Chevrolet Volt, it might only rarely be switched on--depending entirely on driving cycles.

And using a lithium-ion 12-Volt battery, like the one Porsche now offers as an option, could store far more energy than a plain old 12-Volt lead-acid starter battery, offering far greater range before the alternator would have to switch on.

Do you begin to get the feeling that charging ports on cars will become a common thing?

[AutoblogGreen via Hybrids Central]