Previous work for maximizing system lifetime in sensor networks has proposed mechanism such on clustered networks or energy-aware routing protocols. In those works, prediction of lifetime and measurement of energy are dependent on predefined data such as transmission energy, data rate and so on. In common sensor networks, packets are unevenly generated and transmission energy is difficult to measure. Previous work cannot reflect the attributes of real networks. In this paper, we propose a routing algorithm that considers hardware-dependent battery consumption behavior of underlying sensor hardware. Each node reads its current voltage level and estimates its lifetime. Routing is then decided upon the predicted lifetime. Simulation results show that the proposed protocol extends the network lifetime by more than 12% over traditional methods.