Traction Battery Review

Battery Applications & Technology

Traction batteries, also called electric vehicle battery (EVB) are used to provide motive power for electric or hybrid vehicles. The major emphasis on traction battery design is the necessity of a high capacity to weight and volume ratio, since the vehicle must also carry its power source. Traction batteries are frequently deep cycled and require a fast charging rate for use usually within 24 hours. Typical applications are motive power for fork lifts and electric carts. Traction batteries are usually of the tubular plate design, which performs more favorably during deep cycle operation.

Traction batteries differ from Starting, Lighting, and Ignition (SLI) batteries because they are designed to give power over sustained periods of time. Deep cycle batteries are used instead of SLI batteries for these applications. Traction batteries must be designed with a high ampere-hour capacity. Batteries for electric vehicles are characterized by their relatively high power-to-weight ratio, energy to weight ratio and energy density; smaller, lighter batteries reduce the weight of the vehicle and improve its performance. Compared to liquid fuels, most current battery technologies have much lower specific energy; and this often impacts the maximum all-electric range of the vehicles. However, metal-air batteries have high specific energy because the cathode is provided by the surrounding oxygen in the air. Rechargeable batteries used in electric vehicles include lead-acid ("flooded", Deep cycle, and VRLA), NiCd, nickel metal hydride, lithium ion, Li-ion polymer, and, less commonly, zinc-air and molten salt batteries. The amount of electricity (i.e. electric charge) stored in batteries is measured in ampere hours or in coulombs, with the total energy often measured in watt hours.