An extension of distance-aware collision avoidance protocol (DACAP) [1] is proposed that permits its implementation in large networks where maximal connectivity is not available. The technique proposed increases the energy efficiency by optimizing the transmission power of the nodes. The optimal power is the minimal power that still guarantees connectivity between each node and the sink. Simulation results show that this transmission power also results in throughput maximization. For a network of nodes uniformly distributed within a rectangular grid, the optimal transmission range can be determined as a function of the node density. A closed form approximation for this dependence is obtained.