1. An apparatus for estimating a state of charge (SOC) in a battery, the apparatus comprising: a detector unit including a current detector for detecting current from a battery cell, a voltage detector for detecting voltage from the battery cell, and a temperature detector for detecting temperature from the battery cell; a soft computing unit for calculating and outputting a battery SOC estimation value by processing the current, the voltage and the temperature detected by the detector unit using a computing algorithm, which is a fuzzy algorithm implemented as a neural network, the soft computing unit storing the battery SOC estimation value in a memory; and a comparator operably coupled to the soft computing unit and a charger-discharger, the charger-discharger being further operably coupled to the battery cell, the comparator comparing the battery SOC estimation value with a predetermined target value that varies with charging or discharging of the battery, the comparator further providing an algorithm update signal to the soft computing unit to update the computing algorithm based on a learning algorithm when a difference between the battery SOC estimation value and the predetermined target value is outside of a critical range, wherein the fuzzy algorithm has a form expressed as F=Φ(P,X)W, where Φ is one of a fuzzy radial function, a radial basis function, and an activation function in the neural network, P is a learning parameter, X is an input, and W is a weight to be updated during learning.