Yesterday, we shared two divergent opinions from electric utility execs about how prepared the infrastructure may be for the proliferation of plug-in cars. Now we'll reveal how different car types and buyer expectations may dictate what owners and utilities will encounter.
Peter Darbee, who heads Pacific Gas and Electric Corp., based his worst-case prognostications on the assumption that consumers will demand 240- versus 120-volt charging. If what we’ve seen so far is an indication, the assumption is a sound one for battery-electric cars, but not necessarily for plug-in hybrids.
The issue is charging speed. Higher voltage and current — measured in amperes, or amps — make for faster charging. Logically, if you want to fill a larger battery, you need more juice or more time. Battery-electric vehicles rely on large battery packs to provide a viable range. The best examples today are the Tesla Roadster and the electrified Mini Cooper, the latter of which has been leased to 450 individuals in California, New York and New Jersey for a yearlong Mini E Field Trial. The first Mini E recipient, Peter Trepp of Pacific Palisades, California, is shown above.
Both of these plug-ins have lithium-ion batteries and require 240 volts, known as Level 2 charging. Mini and Tesla allow for 120-volt Level 1 charging, but the rate is, uh, problematic: At 120 volts, recharging a depleted Mini E battery to its full 100-120 miles of range takes 26.5 hours. The Tesla Roadster needs 30-plus hours for its claimed 244 miles of range when charged at 120 volts.