NOVELTY - The sensor assembly has a magnetic core including an almost continuous loop of material possessing a high magnetic permeability and two opposing end portions and two opposing side portions defining a central opening. A processor is configured to convert the current flow in the receiving coil to a proportional magnetic signal indicative of the field strength of the magnetic field in the core, so that the magnetic signal is converted to the SOC of the battery cell (14) responsive to the current flow from the receiving coil.    USE - Magnetic sensor assembly for determining state-of-charge (SOC) of battery cell of battery module used in battery system for electric vehicle e.g. electric car (all claimed) and hybrid vehicle. Can also be used in pure plug-in electric vehicle, fuel cell electric vehicle, petrol powered-electric vehicle, diesel-electric hybrid vehicle, extended range electric vehicles (EREV) and electric only vehicles such as battery electric vehicles (BEV).    ADVANTAGE - The durability of battery is improved, while providing useful range information to a driver of the vehicle. The SOC of the battery in electric or hybrid vehicle can be determined accurately.    DETAILED DESCRIPTION - The magnetic core is provided with transverse opening through one of the side portions which accepts a portion of the battery cell extending through opening, so that the portion of the battery cell is positioned within the central opening. A driving coil is wrapped around one of the end portions and is extended across the transverse opening and the portion of battery cell responsive to a driving signal that generates a magnetic field in the core. A receiving coil is wrapped around the other end portion where the magnetic field in the core induces a current flow in the receiving coil. The magnetic core is made of a high-permeability mu-metal-type material. The battery cell is an iron phosphate lithium ion battery cell. An INDEPENDENT CLAIM is included for a battery module for electric vehicle.    DESCRIPTION OF DRAWING(S) - The drawings show the schematic illustration of electric hybrid vehicle and graph showing a relationship between battery cell open circuit voltage and battery cell SOC and between magnetic sensor response and battery cell SOC.    Vehicle (10)    High voltage battery (12)    Battery cell (14)    Power source (16)    Motor (20)