Technical Challenges for Vehicle 14V/28V Lithium Ion Battery Replacement 2011-01-1375

Modern commercial and military vehicles are equipped with more electrical accessories and demand more power than ever before. This causes an increase in the weight of the battery as well as drives the battery to end of life when the vehicle is stationary with the engine off. Lithium ion batteries, which are known for their high power and energy to weight density, long cycle life, and low self-discharge rate, are considered to be an alternative for the replacement of existing Starting, Lighting, and Ignition (SLI) lead acid batteries. Lithium ion battery chemistry offers double the reserve time of the stock battery and a significantly greater number of charging and discharging cycles while providing weight savings. There is no acid inside a lithium ion battery to cause corrosion, which eliminates potential damage to a vehicle from chemical spills and poisonous gases. Due to the slim cylindrical nature of many lithium ion cells, the battery design can be customized in order to fit a space claim in the vehicle. However, the characteristics, including the charge and discharge control of lithium ion battery chemistries, are different from those of flooded and sealed lead acid batteries. The traditional continuous battery charging approach may potentially result in overcharge and thus raise safety concerns for lithium ion battery replacement. In addition, lithium ion batteries experience reduced battery service life when exposed to very low and deep discharge levels. These and other technical challenges of 14V/28V lithium ion battery alternatives charging/discharging control will be discussed. In addition, cost comparisons and safety considerations for different lithium ion battery chemistries for lead acid battery replacement are included in this paper. Although lithium ion battery replacement may have value for vehicle applications that have strict weight and volume requirements, and a need for increased power, their higher cost, low temperature performance, and sophisticated controls may create challenges when they are used in place of traditional vehicle SLI lead acid batteries.