Understanding the thermal response of lithium-ion batteries is imperative to their safe operation. With investigating cooling methods in mind, an electro-thermo hardware-in-the-loop battery emulator is being developed. The emulator will reproduce both the electrical and thermal outputs of a lithium-ion battery. The coupled electrical model is developed from an electric circuit representation of lithium-ion batteries. To run this model, look up tables have been assembled from experiments to select parameters based off a battery s temperature and state of charge. For the coupled electro-thermo model, an isothermal reduced-order model has been modified to account for liquid cooling and convection. It is important to note that the current work neglects the side reactions and mixing terms of the equation as they require in-depth knowledge of the battery s specific materials and concentrations; as such, this approach is only valid for low C-rates (1C or less). The model is compared to experimental data of a Samsung 30Q 18650 battery Results show a good agreement between modeled and experimental results for the battery s electrical and thermal response. Temporal electrical and thermal response for charging and discharging are presented and discussed.