Battery operation - power saving

Hi I would like to enable power saving to be able to run from a battery for as long as possible, is there a step by step guide to this? I assume the developer mode will have to be disabled to start…

I expect the device will spend most of it’s time effectively powered down and perform some minor duties when powered up on a timer. Those duties might include checking sensors and quickly reporting in to the cloud - is that possible with Octave? Most of the guidance seems to expect the device to be continuously powered on…