Application of Statistical Method to Determine Lithium Battery Capacity for Electric Vehicles

In this paper, an empirical method, based on statistical analysis, is proposed to determine correction factor for Li-Po battery capacity calculation. The method uses statistical analysis for the estimation of the battery capacity, using a capacity correction factor previously determined. The method takes into account the effects that the discharge current has on (the) battery capacity. The method has been tested in two types of lithium batteries, Li-ion and LiPo (lithium-polymer), which are the most currently used in electric vehicles, obtaining capacity determination values within a very good accuracy. Although the method requires the full discharge of the battery, the proposed algorithm only needs a short discharge process to obtain the key parameters of the algorithm that set-up the correction factor, from which the real capacity can be determined. The method is very precise and it allows the estimation of the real capacity at any state-of health, what is an essential parameter in many applications like in electric vehicles where determination of real capacity influences the autonomy.