Optimized modeling of Ni-MH batteries primarily based on Taguchi approach and evaluation of used Ni-MH batteries

Abstract

This paper aims to generate an optimized model of the Ni-MH battery based on the Taguchi method and it further aims to evaluate used Ni-MH batteries that served in hybrid electric vehicles and electric vehicles. The status of twelve used Ni-MH batteries is studied to determine their usefulness after their life cycle in automotive applications. The status of used batteries is evaluated by investigating their state of charge, remaining useful life, and degradation in performance. Accordingly, the tested batteries are classified into four categories and they are proposed to serve in different applications. The novelty of the work lies in modeling used Ni-MH hybrid batteries by extracting a model that can define and calculate the battery voltage during the discharging phase, and it can study the influence of design parameters under certain conditions regardless of whether the battery is brand-new or used. Therefore, a second-order model is used to represent the used battery where an explicit mathematical formula expresses the discharge voltage of the new Ni-MH battery at different discharge pulse times, optimized later utilizing the Taguchi optimization method. Finally, the discharge voltage obtained using the developed model for different batteries is benchmarked against the actual measured discharge voltage by calculating the root mean square error.