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Focus EV to use liquid thermal battery control

Car will take its battery pack temperature, then automatically cool or warm it to optimal temperature range before charging or engaging the battery.

Candace Lombardi
In a software-driven world, it's easy to forget about the nuts and bolts. Whether it's cars, robots, personal gadgetry or industrial machines, Candace Lombardi examines the moving parts that keep our world rotating. A journalist who divides her time between the United States and the United Kingdom, Lombardi has written about technology for the sites of The New York Times, CNET, USA Today, MSN, ZDNet, Silicon.com, and GameSpot. She is a member of the CNET Blog Network and is not a current employee of CNET.
Candace Lombardi
3 min read

Owners of the new Ford Focus Electric won't have to worry about going out to warm up the car before driving on a winter's day, the car will warm up its battery pack automatically if left plugged in.

Ford announced Thursday its Focus Electric, due out next year in the U.S., will contain a lithium ion battery pack with a liquid-based thermal management system.

In addition to keeping the car's battery within a preferred temperature range while engaged, the system also kicks in to cool or warm the car's battery pack as needed while it's plugged in for a charge.

Focus Electric Ford Motor

The closed loop system reacts to external temperatures and the battery pack's temperature, then heats or chills the car's battery coolant accordingly before circulating it through the battery pack. On a cold day, the system heats the liquid then pumps it through the battery pack's cooling channels to warm up the battery. On a hot day, the coolant is chilled then circulated through the same system, but in this instance absorbs battery heat and then disperses it through a radiator.

When plugged in to charge, the Focus Electric will always first check its battery pack's temperature, according to Ford. The company explained earlier this month that both the Focus Electric and Transit Connect Electric will have a sensor system using Internet and wireless technology to collect real-time performance data on the car and monitor its battery.

If on a winter's night a traveler, for example, plugs in the Focus Electric to charge and the battery pack is too cold to optimally accept a charge, the car will not engage in charging mode. It will instead have the liquid thermal system warm the battery up to an optimal temperature, then allow the charging to begin. It will then continue to maintain its battery pack's temperature as needed throughout the charging.

Ford calls this preconditioning the battery, a step it says is crucial in maximizing a battery's efficiency and range, as well as elongating the overall battery life.

The lithium ion batteries for the Focus Electric will be made by Compact Power, a subsidiary of LG Chem, Ford announced in July.

While the technology is undoubtedly innovative, Ford is not alone in its choice to use a liquid thermal management system to maintain battery pack temperature. General Motors, which is using batteries supplied by LG Chem in South Korea for the Chevy Volt, also chose to use a liquid heating and cooling system for the battery pack. Tesla has also said it's using a liquid-based cooling system for its electric car battery packs.

Nissan, meanwhile, has said it uses an air-cooling system for the battery pack in its all-electric Nissan Leaf. The method of battery cooling was publicly criticized by Tesla's Elon Musk as "primitive," though some have questioned the validity of Musk's Nissan "trash talk."

The all-electric Focus Electric, which will be built in Ford's Wayne, Mich., assembly plant, will have a range of about 100 miles per charge. It is expected to be available to U.S. consumers in late 2011, and to European consumers in 2012.