Polymer Batteries Lithium Ion (Li-Po), are a main source of currently available portable power used by its high charge density, enabling the development and expansion of mobile technologies. Designers need to know how energy is delivered to design monitoring systems and ensure reliable operation times. This paper presents an estimate of the performance characteristics in Li-Po of 0.4, 0.5, 1 and 2 Ah with the aim of finding the model parameters Peukert's and get uptime on constant current conditions. The result shows the development of a set of tests to adjust the model allowed a margin of error of less than ±1 % of the estimated download time of a Li-Po using their rated capacity and the current value load.