MIT Exploring EV Rapid-Charging Technology
CAMBRIDGE, MA - A team of students at the Massachusetts Institute of Technology is busy testing a rapid-recharging system for electric vehicles, the MIT News Office reported.
These student researchers have already performed extensive testing of the system with an individual battery cell and with a motorcycle they converted to all-electric operation. In coming months, they hope to demonstrate the system on a full-sized sedan they converted. The goal is to demonstrate that recharging can be accomplished routinely in under 30 minutes without severely reducing the operating lifetime of the batteries or causing other problems.
In the year since the MIT Electric Vehicle Team started working on the project, new and established companies have begun to offer commercial rapid-recharging systems. What's more, Japan has officially adopted a new standard for the connectors for such systems and has begun installing the systems in more than 100 locations.
The Nissan Leaf, a pure electric five-passenger car to be introduced in the U.S. later this year, is already capable of rapid recharging in 30 minutes in places that have the necessary "Level III" charging system. But so far, just one such station exists in the U.S. That's in Portland, Ore., MIT said.
Lennon Rodgers, a doctoral student in mechanical engineering and a member of the MIT Electric Vehicle Team, presented a paper on the team's rapid-charging tests at the 12th International Conference on Advanced Vehicle and Tire Technologies in Montreal. The paper was co-authored by fellow team members Radu Gogoana, a master's student in mechanical engineering; Paul Karplus, an undergraduate at Stanford; and Michael Nawrot.
Rapid charging, also known as Level III, requires much higher voltages and current than what's supplied by conventional household circuits. The Japanese rapid-charging standard, called CHAdeMO, provides DC power at up to 500 volts with a current of 125 amps.
Typical chargers operate on standard AC power, using either 110 volt household current (Level I), which generally can recharge an electric car's batteries overnight, or special systems that use 220 volts (Level II), which can cut the charging time in half.
"Rapid charging" systems typically refer to those that can charge the batteries to at least 80 percent of capacity within 30 minutes. This fast-recharge technology might be installed in central recharging stations comparable to today's gas stations, where the cost of the necessary infrastructure could be warranted and where a fast turnaround is necessary, MIT said. In many cases, rapid charging systems can provide a 50 percent charge -- typically enough to travel 50 miles -- in under five minutes. That's comparable to the time it takes to fill a gas tank.