A new compact, lightweight 48-volt lithium ion battery from U.S. supplier Johnson Controls Inc. debuting today at the Frankfurt auto show is small enough to fit under the hood of most vehicles and powerful enough to run an air conditioner.
Johnson Controls designed the battery for use in mild hybrid vehicles. Mild hybrids, also called micro hybrids, use an electric motor to help propel the vehicle when it is accelerating. The electric motor alone does not power the vehicle.
The more powerful battery would work in tandem with the vehicle's traditional 12-volt system, which would continue to power the vehicle's lights, radio and other functions. But when higher voltage is needed, the 48-volt battery would supply the power.
The dual battery system adds complexity but the payoff is a fuel economy gain as high as 15 percent, according to Johnson Controls.
The 48-volt battery captures and stores more energy from regenerative braking than the batteries used in today's mild hybrids. The added capacity could be used to help propel the vehicle and to power accessories requiring high voltage, such as seat heaters, active chassis control systems and the air conditioner, one of the biggest power drains on the vehicle.
On most vehicles, the air conditioning compressor is connected via a rubber belt to the front of the engine and requires around 5 hp to run. The 48-volt battery would enable the compressor to be decoupled from the gasoline engine. The compressor would be run by electricity captured by the vehicle's regenerative braking system.
Electric air conditioning compressors, such as Denso's e-Compressor, are in production on the Toyota Prius and Ford C-Max hybrids.
"Micro hybrid systems will be able to support the automotive industry's needs at a much lower cost than hybrid or electric vehicles," said Ray Shemanski, vice president of Johnson Controls Power Solutions.
Mild hybrids, such as the Chevrolet Malibu with e-Assist, have a separate lithium ion battery pack in the trunk that requires a cooling system. The Micro Hybrid battery would eliminate that and saves weight.
Shemanski said the battery will be ready for testing this year.
He said, "We expect this technology to play an integral role in meeting aggressive fuel economy and emissions reduction targets."