Piezoelectric elements can be used to harvest electrical
energy when impact forces are applied to their surfaces. Often, however,
only the peak voltages, or peak power output is used as a measure of device
performance, and the total energy harvested during an impact force is
overlooked. For energy harvesting applications, such as small-scale
piezoelectric batteries, the total energy generated over an impact cycle
should be considered. In this paper the total energy efficiency of several
commercially available piezoelectric materials are evaluated using impact
testing. The results revealed that different materials have significantly
different energy efficiencies due to factors such as material type and
device construction. Further, it was found that peak power output is not
always the most appropriate measure of device performance for energy
conversion applications.