One of the major drawbacks holding electric vehicles (EVs) from gaining market share is the fact that their batteries weigh a lot, limit their range (to about 100 miles), and take a long time to recharge.
EV batteries take from 15 minutes to more than five hours to charge, depending on your home’s wiring (110-volt versus 220-volt) and the batteries recharging capability. Batteries that have a 220-volt charging system (think Nissan EV-02
) can take as little as four hours to reach a full charge from depletion.
Using modern EV recharging stations, said batteries can reach 70-percent of charge in two hours, and the 2010 Smart fortwo
boasts a 71-mile range on a charge of only three hours.
Some of these times sound pretty good, until one realizes that the fast charge often means a smaller battery and an equally fast discharge, limiting ranges to under 30 miles in some cases for an all-electric vehicle.
In terms of range, nickel metal hydride batteries appear to offer the best hope, offering drivers up to 320 miles between charging
, yet lithium-ion remains the favorite, if only because the research has been done.
) and Fisker Automotive
, instead of trying for lighter batteries packing more charge, are looking at an onboard gas-powered generator
to recharge EV batteries while driving, but that seems like a cheat, and means EVs move closer to conventional vehicles – a no-no for the truly green-minded.
Now scientists at the Fraunhofer Institute for Chemical Technology
in Germany are looking at redox flow batteries – that is, a battery with two liquid electrolytes, both of which can be readily replaced to recharge the battery.
Redox flow batteries aren’t new, and have historically faced the problem of storing less energy than lithium-ion batteries, minimizing ranges to 25 miles. However, new prototypes suggest that simpler, bipolar batteries using lithium cobalt dioxide-coated positive electrodes (lithium polymer technology) will result in lighter batteries with four times the charge. A prototype
1.48-ounce battery discharges at 3.9 volts, with a rating of 125 mAh (maximum Ampere hours), and a system-specific response suggests that the battery can even be overcharged without harm.
The old fluid is recharged and delivered to other EVs, meaning no waste and no chemical pollution, and though the redox is only a slight improvement on lithium-ion batteries so far, its potential is huge, especially for drivers accustomed to stopping for a “fill-up” at the nearest fueling station.
In fact, the biggest problem might be designing the fill process, since leaving it to drivers to decide which fluid goes where might see Fraunhofer’s redox technology suffering a short life span thanks to litigation.
Even so, this is better than the scheme that had service stations storing (and recharging) thousands of EV batteries for instant, drop-in service by technicians. When is the last time you went to a service station and found a live human being who could do more than make change?