Liquid-Cooled Battery Helps Extend Ford EV Range
DEARBORN, MI - The all-new Ford Focus Electric, which debuts in the U.S. late next year and in Europe in 2012, will be powered by an advanced lithium-ion battery that uses heated and cooled liquid to help extend battery life and gas-free driving range.
Thermal management of lithium-ion battery systems is critical to the success of all-electric vehicles because extreme temperatures can affect performance, reliability, safety and durability, Ford said. That's why the automaker has chosen an advanced active liquid-cooling and heating system to regulate the temperature of its lithium-ion battery packs, which are designed to operate under a range of ambient conditions.
"All-electric vehicles do not have a conventional engine on board, so it is critical we maximize the performance of the battery under various operating temperatures," said Sherif Marakby, Ford's director of electrification program and engineering. "Active liquid systems are more effective than air systems at regulating lithium-ion battery temperature. As a result, the active liquid system on Focus Electric will play a key role in providing our customers with the best performance possible."
The active liquid cooling and heating system also enables the Focus Electric to automatically precondition the battery pack temperature during daily recharging. When the vehicle is plugged in to the power grid, the vehicle system can warm up the battery on cold days and cool it down on hot days.
The Focus Electric will be built at Ford's retooled Michigan Assembly Plant and will be available in late 2011. The vehicle will have an expected range of up to 100 miles and use no gasoline at all.
While air-cooling methods work well for many of today's smaller car battery systems, the larger, more complex lithium-ion battery technology powering Ford's all-electric vehicles calls for an aggressive thermal management system, Ford said.
An active liquid system heats or chills a coolant before pumping it through the battery cooling system. This loop regulates temperature throughout the system against external conditions.
On hot days, chilled water absorbs heat from the batteries, dispersing it through a radiator before pumping it through the chiller again. On cold days, heated water warms the batteries, gradually bringing the system's temperature to a level that allows it to efficiently accept charge energy and provide enough discharge power for expected vehicle performance.
"Extreme temperatures impact a battery's life and performance, making it crucial to have an effective cooling and heating system to regulate temperature for these demanding applications," said Anand Sankaran, Ford's executive technical leader for energy storage and HV systems.
The liquid cooling system also plays a role in charging the vehicle. When the all-electric Focus is plugged in to recharge, the vehicle control system will automatically precondition the battery, if needed, to the optimal temperature before accepting charge. If the battery is already at the optimal temperature, the system will automatically accept charge and maintain an optimal temperature.
"We are working closely with our technology partners to accelerate the development of our lithium-ion battery systems to help our future EV customers get the most out of their vehicles," Marakby said.
The Focus Electric is one of five electrified vehicles Ford will release over the next three years. In addition to the Focus Electric, the Ford Transit Connect Electric small commercial van arrives in late 2010, followed by two next-generation hybrid electric vehicles, as well as a plug-in hybrid electric vehicle in North America in 2012 and Europe in 2013.