Reduce power consumption and schedule power on and off with RTC module?
You can do that with this module, but you may need some additional circuit. 

The SQW output of the DS3231 can be programmed to output an alarm (active low) when the internal time registers match a certain predefined value. You can use this alarm/SQW signal to power-up your beehive scale (arduino &amp; Co.) e.g. with a single high-side transistor between the battery and the arduino. 

After Arduino has done its work, it must reprogram the DS3231 over I2C for a new wakeup time, e.g. 15mins later. At last, the arduino must reset the interrupt which also shuts down the arduino from power.