A wireless mesh network includes a mesh of continuously-powered devices (CPDs) and a mesh of battery-powered devices (BPDs). The BPDs are organized into hop layers based on hopping distance to the mesh of CPDs. The CPDs transmit time beacons to BPDs in a first hop layer during a first receive window associated with the first hop layer. The BPDs in the first hop layer then transmit time beacons to BPDs in a second hop layer during a second receive window. In this manner, the wireless mesh network propagates time values throughout the BPD mesh. Based on these time values, the BPDs power on during short time intervals to exchange data with neighboring BPDs, and then power off for longer time intervals, thereby conserving battery power. The techniques described herein for conserving battery power for BPDs may also be applied to conserve power consumption of CPDs.