Vehicle batteries performance requirements

The requirements for secondary batteries installed in electric and hybrid vehicles are as follows. The safety and reliability of the batteries in the vehicles must be ensured. Furthermore, from the standpoint of adopting the batteries in the vehicles, their performance requirements can be broadly classified into (1) energy density (2) power density and (3) cost. Lead-acid batteries have been employed since the first EV was put into practical use in the 1890s. The batteries are low cost and easy to use, but their energy density is low. Initially, they were installed in electric and hybrid vehicles due to a lack of alternatives. However, it was realized the lead-acid batteries are too large and heavy to be used in vehicles, and therefore, the batteries did not achieve full-scale adoption or popularization beyond a few EVs and HEVs. 

In the 1990s, the use of batteries in electric vehicles and for load leveling is being revived partly for environmental reasons and partly because of scarce energy resources. Improvements in battery performance and life, fewer maintenance requirements, and automatic control systems are making these appHcations feasible. Research and development is ongoing all over the world to develop improved lead—acid batteries as weU as other systems to meet these needs. 

At present, there is hardly a market for widespread EV use. Were it to emerge in the near future, no electrochemical plants would be ready to power electric vehicles, except for the lead-acid battery. The development of candidate systems, capable of better performance, requires a long time and extensive scientific and... 

With these preparations, we can equate the driving performance of an EV/HEV and the basic battery specifications. To fully understand the vehicle driving performance, the forces and energy consumptions are required to be correlated to form dynamical equations. There are several resistive forces associated with vehicle driving ... 

The performance specification and the acceptable cost of a battery depend, of course, on its application. Here we are concerned with traction batteries, primarily for use in road vehicles, and we have concentrated our attention upon urban buses and light delivery vehicles. In order to define the battery performance targets it is first necessary to consider the operational problem from the point of view of the traffic manager, who specifies the journey profile which the vehicle must be capable of making, and then to select a particular design of vehicle in order to interpret this duty cycle in terms of energy and power requirements and the permissible mass and volume of the battery. When this was done, we arrived at a specification of battery performance for each class of vehicle (Table l). 

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