Abstract: Mobile Ad Hoc Network (MANET) is a technology that operates on portable devices such as IPAQ Personal Digital Assistants (PDA), smartphones, laptops and other mobile devices. Habitually, all these devices run on batteries; therefore, the need of sufficient power poses a critical issue in the operations of these devices in the network. This research was conducted to compare and analyse the number of nodes keeps alive in the Mobile Ad-Hoc Network (MANET) in order to find out the best way to manage the mobile devices. The NS2 simulation tool was used to conduct the experiment focused on Optimize Link State Routing (OLSR) protocol. The scenario was created based on four elements; the space of network, the different number of nodes located in the network, the different speed of nodes and the different speed of the network. The results from the experiment show that all the four elements give a significant impact to the energy usage for mobile devices. Lastly, the matrix solution table for high speed of nodes and high speed of networks is proposed. This matrix solution table can be used as a guideline for the decision maker or researcher to select the suitable elements that suite to their scenario.