title: Putting arduino to sleep due to depleting battery power
body: <p>I have built a data-logging functionality using sd card and ds-1307. T continuously record temperature data. However since this functionality is powered by battery, I intend to monitor for the battery power and put the circuit to sleep for an extended time frame. During this mode I would like to disable the data-logging and rtc module from drawing power just like arduino. This sleep mode could for a day or a month until a battery is replaced. How to achieve this programatically?</p>