 in Tennessee has developed a prototype system that could let drivers cut the time needed to fully recharge from a home electrical outlet by a factor of 10—from about eight hours to about 45 minutes.)
CHARGE!: U.S. Department of Energy's Oak Ridge National Laboratory (ORNL) in Tennessee has developed a prototype system that could let drivers cut the time needed to fully recharge from a home electrical outlet by a factor of 10—from about eight hours to about 45 minutes.
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When plug-in hybrid electric vehicles (PHEVs) start hitting the road later this year, most drivers will plug into a normal 110-volt outlet when not driving in order to trickle charge life back into their car's battery. Whether this is a feasible model is an open question, with some consumers concerned that trickle charging may not be fast enough to sufficiently recharge batteries between trips. Without a charged battery, PHEVs rely on their internal combustion engines, something hybrid drivers aim to avoid.
To address this concern, a team of researchers at the U.S. Department of Energy's Oak Ridge National Laboratory (ORNL) in Tennessee has developed a prototype system they say could let drivers cut the time needed to fully recharge from a home electrical outlet by a factor of 10—from about eight hours to about 45 minutes. The good news is that drivers would be able to use outlets that deliver 240 or 220 volts to get this level of fast charge. This ability to accommodate a higher voltage and current means the battery can recharge at about 20 kilowatts, as opposed to the two kilowatts possible with a 110-volt outlet. The bad news is that drivers would have to upgrade their home electrical systems to accommodate 240- or 220-volt outlets, if they do not already have them to run clothes dryers or other appliances.
A plug-in hybrid electric uses a traction-drive power electronics system to propel the car forward by providing force to the car's wheels and has a charger for recharging the high-voltage battery when it is plugged into the power grid. The traction-drive system typically consists of a boost converter (which steps up voltage when the electronic circuit requires a higher operating voltage than the battery can provide alone), two inverters (which take direct current (DC) voltage and convert it to alternating current (AC)), and electric motors to provide motive power (pdf).
ORNL's prototype drive system has those same components but uses the inverters to charge the battery from an outlet, eliminating the need for a separate charger and enabling the car to recharge faster and more efficiently, says Gui-Jia Su, a senior research engineer at ORNL's Power Electronics and Electric Machinery Research Center. Although a standalone onboard battery charger in most PHEVs costs only about $300 for the slow charge rate (two kilowatts), ORNL's technology would also be able to replace fast-rate 20-kilowatt chargers, which can cost several thousand dollars, according to Su.
The new system is also designed to allow a PHEV to use its battery as an energy storage device, enabling the car to hold electrical energy in the battery while the grid has surplus power (during off-peak hours, for example) and contribute its surplus energy back to the grid when the latter needs more power to meet peak demand, Su says.
ORNL is proposing to use the inverter to charge the battery rather than having a separate onboard charger, says Andrew Frank, a University of California, Davis, professor of mechanical and aeronautical engineering. The idea is to use the inverter controllers to recharge the battery. Such a system could also be used to take energy from the car and use it to power a house or return it to the grid, he acknowledges.
But the market for ORNL's technology is a tough one to crack. AC Propulsion, a San Dimas, Calif., maker of electric vehicle drive systems, discovered this when working with Tesla Motors. The electric vehicle–maker initially licensed a drive system design and reductive charging patent from AC Propulsion but later developed its own versions of these technologies. The major automakers are likely to take the same route, developing their own technologies, Frank says.
Although ORNL's proposed system would allow PHEV-makers to leave out the onboard charger that they currently install in their cars, the first-generation PHEVs are not intended for high-speed charging, says Frank, who is also founder of Efficient Drivetrains, Inc., a U.C. Davis start-up that designs energy-management systems for electric vehicles and hybrids. "One of the issues with fast charging is that the more power you use to recharge the battery, the less efficient the charging system is, and a lot of power is wasted," he says. "For this reason, you really want to use a trickle-charge system for a PHEV, otherwise you're throwing away electricity, not to mention money."
ORNL's technology could have a much greater impact on purely electric vehicles such as the upcoming Nissan Leaf or Ford Focus RV, which do not have a combustion engine to rely on, meaning depleted batteries need to be charged quickly for the car to be practical.
The Energy Department likes the technology's potential and has invested more than $1.3 million in ORNL's project since 2008. Now the researchers are looking to license their drive system to a company that can commercialize it. Su says that several companies, including Raser Technologies (a maker of drive systems) and MBtech (which provides engineering and consulting services to the auto industry), have expressed interest in the system, although they have not discussed details as to how the technology might fit into these companies' existing offerings.
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12 Comments
Add CommentThese nitwits assume that a EV owner is going to cut his battery life in a quarter by allowing grid operators to run it up and down during the day as they see fit. AS IF!!
Reply | Report Abuse | Link to thisThere will be very little daytime storage from EVs.
It's not necessarily an either/or proposition. The slower 110v charge may be acceptable for homeowners who return home and charge the car overnight; the "fast" 220v charge is necessary for the "in between" trips--charge the car while grocery shopping, at work, or the doctor's office. While this would not require homeowners to upgrade their electrical systems (the standard plug in the garage would work), it would require a significant investment in a public charging infrastructure. See the work the Rocky Mountain Institute's Project Get Ready, on this issue for example.
Reply | Report Abuse | Link to thisI imagine the ability to send power back to the grid could be configurable and/or activated on user demand.
Reply | Report Abuse | Link to thisThe power goes out. You head out to the garage and start fiddling with the car's control panel. "What are you doing?" your spouse asks. You reply: "I'm rerouting power from propulsion to life support." On come some of your lights.
AC Propulsion did this 20 yrs ago so why is it new? Many UPS systems have done this sense the 60's at least.
Reply | Report Abuse | Link to thisWhile I don't put power back into the grid, while power was off in our hurricane time here in Fla I used my EV's to power my home for 3 days. with an inverter.
The new SAE EV plug standard, easily installed in a home for $100, already does this almost fast charging as stated in the article. If one has as most do a dryer outlet or a stove one can plug into it with an adapter.
So almost everything thing here is old news.
Being able to charge your plug-in hybrid at work is huge because it will allow car buyers to cut the battery and the price of his new hybrid by half. The $40K Volt will drag GM to its death. If new buyers could say give me half the battery for $25K and I'll recharge it at work, then it could save GM.
Reply | Report Abuse | Link to thisProcrastination and ignorance will eventually destroy the American economy. These "last century" battery manufacturers are desperate to keep their outdated batteries in the market by inundating the system with worthless information.
Reply | Report Abuse | Link to thisWe have liquid metal batteries, and liquid salt batteries that can hold an incredible amount of power and can take any electrical car thousands of miles before it needs recharged, and it takes very little electricity to recharge them. The liquid salt battery can be recharged with a small solar panel on top of your car or garage. So why are we still wasting time and money on these old acid batteries?
JamesDavis...please post any links on the batteries...very interested....thanks...
Reply | Report Abuse | Link to thisCan someone explain you increasing the voltage to 220 can increase the power available to 10 times that available at 110 volts? P=IE as I remember, so power is linear with Voltage not 10 times!! Seems to me the best you could do is double the power all other things being equal.
Reply | Report Abuse | Link to thisI am sure the 10x speed increase in charging is partialy due to the way the two different sytems work (see below) but one thing not to forget is that home 110v systems are limited to 15-20 amps which can deliver a maximum of 2200 watts (and you really don't want to run them at max for 8 hours straight) and 240v systems (due to far more robust wiring and two hot wires) can deliver 40-60 amps and thus upwards of 14,400 watts or almost 7 times the power. (power = watts = amps x volts). However, the trickle charger is probably limited to something like 10-15 amps (1100-1600watts) where as the EV's onboard inverters that are also used by the drive system probably have limits that are somehwere in the 100-200 amp range. So unlike the trickle charger, there is no bottle neck.
Reply | Report Abuse | Link to thisI am sure the 10x speed increase in charging is partialy due to the way the two different sytems work (see below) but one thing not to forget is that home 110v systems are limited to 15-20 amps which can deliver a maximum of 2200 watts (and you really don't want to run them at max for 8 hours straight) and 240v systems (due to far more robust wiring and two hot wires) can deliver 40-60 amps and thus upwards of 14,400 watts or almost 7 times the power. (power = watts = amps x volts). However, the trickle charger is probably limited to something like 10-15 amps (1100-1600watts) where as the EV's onboard inverters that are also used by the drive system probably have limits that are somehwere in the 100-200 amp range. So unlike the trickle charger, there is no bottle neck.
Reply | Report Abuse | Link to thisWhen you can buy electricity cheep,at night and then sale it back during the day for a profit.Having several batteries at home would seem like a good investment?Your home electric bill would go down and who knows depending on how many batteries you have they could pay for them selves,and you could get your electricity for free.
Reply | Report Abuse | Link to thisWayne, just run a search right here on SciAm and every one of the articles on advanced battery research will appear.
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