This paper evaluates the impact on the performance of limited battery energy in ad hoc networks. In the literature, the widely adopted assumption is to have nodes with an infinite energy, but this assumption does not consider that a terminal power itself by means of battery, which can easily exhaust its energy. When a node switches off, as a consequence of an energy fall, its support to the ad hoc network functionalities, such as routing signaling management and packet forwarding, disappears, with a consequent impact on the global network.