NOVELTY - The method involves estimating cell-lumped internal electrical resistance of battery cells, cell-lumped conduction resistance between core (18) and surface (20) of battery cells (16), and a cell-lumped convection resistance (Ru) between the surface of battery cells and coolant (22), to determine core temperature value of the battery cells. The core temperatures (Tc) for battery cells in battery pack is estimated, using thermal energy transfer effects between coolant and battery cells, thermal energy transfer effects among the battery cells, and the estimated core temperature values.    USE - Method for estimating core temperatures of battery cells in battery pack of battery such as lithium-ion battery used in vehicle. Can also be used in nickel-metal hydride battery used for mobile phone, tablet and laptop computers, hybrid electric vehicles, plug-in hybrid electric vehicle, battery electric vehicle, industrial equipment such as forklift and robot, stationary power generator such as solar power generator and wind power generator.    ADVANTAGE - The core temperature of the battery cell of battery pack can be estimated accurately and reliably in a precise manner. The core temperature estimation can be used for battery thermal management system operation and to facilitate maintaining safety, performance, and longevity of the battery pack. The core temperatures for all of the battery cells in the battery pack can be estimated using thermal energy transfer effects and without providing sensors or otherwise physically measuring temperature at all of the cells. The accuracy and preciseness of the core temperature estimation can be facilitated by a closed-loop feedback functionality which can eliminate the need for initial temperature determination of the battery cell.    DETAILED DESCRIPTION - The surface temperature (Ts) and current (I) of battery cells in the battery pack, inlet temperature (Tf) of coolant provided to the battery pack, and a flow rate or velocity of the coolant are received. INDEPENDENT CLAIMS are included for the following:    (1) computer readable medium storing computer program for estimating core temperatures of battery cells in a battery pack; and    (2) system for estimating core temperatures of battery cells in battery pack.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the parameter identifier and adaptive observer used with the system for estimating core temperatures of battery cells in battery pack.    Lithium ion battery cells (16)    Core of battery cell (18)    Surface of battery cell (20)    Coolant (22)    Input current (I)    Convection resistance (Ru)    Core temperature (Tc)    Coolant temperature (Tf)    Surface temperature of battery cell (Ts)