New Wrinkle in Hybrid Cars
rm
WITH the electrification of the automobile gaining momentum each day, a dizzying
variety of hybrid, plug-in hybrid and pure electric drive systems are heading to
market in coming years.
Multimedia
Slide Show
BYD F3DM
Related
* Behind the Wheel | BYD F3DM: BYD Is the First Ripple in a Potential Chinese
Wave (February 20, 2011)
* Where Are the Chinese Cars? (February 20, 2011)
With each new model, consumers will grasp for precedents. Is that new
electric-drive vehicle most like a battery-powered Nissan Leaf or a Chevy Volt
plug-in hybrid? Or is the Toyota Prius gas-electric the right benchmark?
When it comes to the BYD F3DM, a Chinese car expected to go on sale in the
United States early next year, the right answer may be, “All of the above.”
The F3DM starts with the platform of the front-drive BYD F3, China’s proven best
seller, and adds a 16-kilowatt-hour battery pack and two alternating current
electric motors. Its operation is sometimes closest to a pure electric vehicle;
at other times it’s closer to a conventional hybrid. BYD calls it a dual mode —
the DM part of the F3DM name.
BYD engineered the car to drive mostly on electricity. After an overnight charge
of the battery pack, drivers will punch the dashboard E.V. button and drive off
using only energy from the lithium-iron-phosphate battery. This chemistry is not
as effective at storing energy as the lithium-manganese formulas used in the
Leaf and Volt, but BYD says it makes the tradeoff in the interest of safety and
durability. For simplicity and cost containment, the F3DM does not have an
active thermal management system for the battery — something that the Volt
engineers say is crucial to cell longevity.
The motors are a 50-kilowatt unit that drives the wheels and a 25-kilowatt
helper that can send power to the wheels or generate electricity through
regenerative braking. As long as the charge level of the F3DM’s batteries is
above 20 percent, the two motors handle all the work; 30 miles or so down the
road, the car automatically switches from E.V. operation to hybrid mode.
At that point, the F3DM’s 1-liter 3-cylinder engine is called into service to
bring the battery charge as close as possible to 30 percent, effectively
extending the range of the vehicle by hundreds of miles, just like the Chevy
Volt.
There is a direct connection between the gas engine and the wheels, a Prius-like
approach that comes in handy when accelerating onto a highway. In high-load
circumstances, the 68-horsepower gas engine combines with the electric motors
for a total of 168 horsepower.
The size of the battery pack matches the Volt’s capacity at 16 kilowatt hours.
Yet, there are major differences. The F3DM uses 100 3.3-volt cells stored under
the cabin; the Volt uses 288 lithium-manganese-spinel cells arranged in a
T-shape down the vehicle’s center.
The F3DM’s 1-liter 3-cylinder engine is a pipsqueak, but perfectly suited for
its primary role of recharging the batteries. BYD showed a bit more flair by
including a rooftop solar panel as a standard feature. It’s more show than
substance, but does provide some electric energy to run vehicle accessories like
the radio and climate control. In the end, the solar panel probably doesn’t add
much cost, because BYD is one of the world’s largest manufacturers of
photovoltaic cells, in addition to being a global leader in lithium-ion
batteries.