The latent heat storage capacity of phase change materials is frequently used for transient thermal energy storage in high heat flux environments. However, direct measurement of heat fluxes or surface temperatures on the heated surface is difficult in high temperature experimental setups. Instead, thermocouples can be immersed in the phase change material and unknown heat transfer properties, such as flame temperature and the heat transfer coefficients, are approximated using an inverse heat transfer algorithm. In this work, a two model inverse heat transfer algorithm is implemented, where a low temperature model without phase changes is used to approximate a subset of the unknown heat transfer properties. These results are then fed as initial conditions to a high temperature phase change model for the entire experimental duration for determination of the unknown heat transfer properties across the entire temperature range. The two model approach reduces the effective dimensionality of the solution space, improving convergence radius and speed.