TCP suffers dramatically when implemented within wireless multi-hop ad-hoc networks due to its specific characteristics (e.g. mobility and being battery dependant). Being battery operated, ad-hoc network nodes have to be energy conservative. Many researches investigated the performance of TCP in terms of throughput and/or energy consumption. Energy consumption studies, however, were only partial. This paper introduces complete, detailed measurements of TCP's energy consumption resulting from both communication and computational energy costs. Our measurements are realized using a hybrid approach, combining simulations and realistic test-bed configuration. Our study is conducted taking into account different TCP variants facing various data loss situations within the network. The obtained results show the impact of TCP's congestion control algorithm on TCP's energy cost.