Battery tech is key in achieving “Green” transportation goals

Thomas McAlpine, IHS Technology



Thomas McAlpine, IHS Technology

Batteries are used extensively in both gas powered and electric powered automotive vehicles. In gas powered vehicles the battery is typically used to ignite the engine and run low power devices such as lights and the audio system. In full electric vehicles the battery is used for propulsion.  Hybrid electric vehicles use a combination of battery power and a combustion engine to propel the vehicle.

Batteries used in pure gas powered cars are relatively inexpensive and are typically flooded lead-acid (FLA) technology. FLA batteries are reliable and resilient however they are typically a lot heavier than other battery chemistry’s such as lithium-ion and nickel batteries.

Start-stop system adoption in passenger cars is predicted to reach over 35% by 2018.  Start-stop systems improve the fuel efficiency by around 5-10% and operate by automatically shutting down the engine whilst the car is idle. Once the clutch is depressed the battery then restarts the engine again. In start-stop systems the demand on the battery is a lot greater as it needs to crank the engine multiple times during a single journey. Due to the larger number of cranking cycles higher performing batteries with a longer lifecycle are required.

Advanced lead-acid batteries are currently the technology of choice in start-stop systems with the specific technology varying between valve-regulated lead-acid (VRLA) and enhanced flooded lead-acid (EFLA). One disadvantage with using advanced lead-acid batteries is that they are more expensive to manufacture and therefore cost OEMs almost twice the amount of FLA batteries.

Electric road vehicles typically use lithium-ion or nickel metal hydride batteries as the energy density is superior to lead-acid batteries allowing for a lightweight solution. Batteries used in full electric vehicles typically consist of close to 100 cells and batteries used in hybrid electric vehicles typically consist of around 60 cells.

Nickel batteries are currently used in a number of hybrid vehicle models such as the Toyota Prius; however the adoption of nickel batteries is projected to fall from 81% in 2013 to 54% in 2018 adoption of and transition to lithium-ion batteries occurs.

With few competing technologies, it is becoming increasingly important to make lithium-ion batteries operate more efficiently.

Battery management IC suppliers need to address both the safety and efficiency characteristics of the battery pack. Highly integrated cell monitor ICs are used in electric vehicle systems which typically monitor the battery cells, balance the charge between the individual cells and provide protection to the battery from extreme voltage conditions. Many battery management designs include back up cell monitoring ICs as a safety precaution in the case of primary cell monitor IC malfunction.

With demand for electric vehicles projected to increase rapidly and the transition to start-stop vehicles predicted to continue, IHS projects that the battery management IC market in automotive vehicles will grow by 55% in the next 5 years to be worth $140 million by 2018.

The balance between the performance and cost of low carbon-emission vehicle systems remains a business tightrope with industry advancements in battery efficiency and battery price erosion important in ensuring the economic viability and success of “Green” transportation.