Energy-harvesting shock absorbers (EHSAs) have been introduced in the last decade as a viable technology for improving the performance and durability of electric and/or hybrid vehicles. However, in order to gauge the potential that can be obtained from this technology in different environments, the computational models that are used should behave as close to reality as possible. One of the limiting factors in EHSAs, in terms of recoverable energy, is frictional losses between its moving parts. Depending on the friction losses, the dynamics and efficiency of the system will vary. This paper presents a method of identifying the friction parameters in a ball-screw energy-harvesting shock absorber (BS-EHSA) system for subsequent computational simulation. In addition, it shows qualitative and quantitative results of how these friction parameters could affect the comfort and adhesion of the vehicle, as well as the generated power and energy efficiency of the BS-EHSA.