Vibro-impact energy harvesters (VI-EH) make use of vibrations generated in the world, with attention on that induced by humans. The appeal of devices using VI-EH is that these devices can be put in locations where it is otherwise difficult to provide power or replace batteries. The performance of vibro-impact energy harvesters in their applied settings depend heavily on the environment, which affect the expected amplitude and frequency of vibrations experienced by the system. Analysis for dynamical systems in this application have focused solely on harmonic forcing at a single wave frequency. This approach fails to capture the effects of forcing by multiple wave frequencies and anharmonic forcing, both of which are commonly seen in real life and experiments. Here, we look at a previously described model of a VI-EH, and consider anharmonic forcing (triangle and square wave forcing) as well as fourier series approximations and seeing the interplay of multiple wave frequencies. We demonstrate that the motion due to truncated fourier series well approximate anharmonic forcings while having significant difference in location of bifurcation.