Although increasing the network lifetime and maintaining network connectivity is an important design issues in MANETs, a more challenging task is to effectively utilize the mobile node's limited battery power to achieve the aforementioned. Mobile nodes not only consume its battery power, when it actively communicates over the network, but also when it is idle. Thus far, different energy efficient routing mechanisms have been proposed to minimize the energy utilization of mobile nodes during its active and inactive periods. But, there is no specific mechanism which would suit for all network scenarios. However, much of the mechanisms are more suitable only to certain network scenarios. This research paper was aimed to provide in-depth knowledge on energy limitations and energy aware routing challenges in MANETs so far. © 2014 IEEE.