In ad hoc mobile wireless networks, energy consumption is an important issue as most mobile hosts operate on limited battery resource. Existing models for evaluating the energy consumption behavior of a mobile ad hoc network have shown that the various components of energy related costs include transmission power as well as power of reception. In this paper, we extend the model for calculating the energy spent at a node due to a flow in the network. We include the transmission and reception costs if the node belongs to a flow, and reception costs if it is near a flow. The model gives the energy costs of nodes in ideal conditions where interferences and collisions are absent, and hence can be extended to evaluate the effect of interference between flows on energy consumption in more realistic conditions. The collisions due to the flows are also measured, which are used to evaluate the effect of such interference in the energy consumption. We then show how the extra energy spent due to collisions can be calculated by predicting the collisions in the nodes of the network. This prediction is shown to be capable of accurate calculation of the extra energy consumption.