Tuesday, January 26, 2010
"Speed Bumps Ahead for Electric-Vehicle Charging"
Eectric powered vehicles sound really good; HOWEVER, there's this problem...
This is part of a post at Spectrum.IEEE.org website:
"EVs need lots of power, especially when charged quickly. Utilities bet that most buyers will want a 240-volt charger that can "fill the tank" of a modest-size EV in 2 to 3 hours, four times as fast as a standard 120-V charger can. Such 'AC Level 2' chargers, as defined by the Society of Automotive Engineers' emerging J1772 standard, draw up to 6.6 kilowatts. Turning one on is like adding up to three homes to a neighborhood, and that's with the air conditioning, lights, and laundry running.
Turning on two or three Level 2 chargers could burn out the street-level transformers that are the distribution grid's weakest link. Most utilities employ undersized transformers, which are designed to cool overnight. Without time to cool, sustained excess current will eventually cook a transformer's copper windings, causing a short and blacking out the local loads it serves"
