We use simulations to study the comparative routing overheads of three ad-hoc routing protocols, namely AODV, DSDV and DSR. In contrast to earlier studies, we focus exclusively on the energy consumption and not on other metrics such as the number of routing packets. In particular, we study the 'range effects' of the three protocols, i.e., how changes to the transmission power and transmission radius affect the overall energy consumed by routing-related packets. Due to the broadcast nature of the wireless medium, the energy spent in packet receptions is almost as important as the transmission power; using the number of transmissions as an indicator of the routing overhead can thus be fairly misleading. Our studies show that the energy overhead of the three protocols varies with the transmission power in distinct and non-obvious ways.