Sorry to bump this old Thread.
But i thought i give some Info in case anyone stumbles on it via searching am312+mysensors like i did some Weeks ago.
I used the banggood Module for a Battery Powerd Node.
At first it was running from 3xAAA Alkaline Batteries.
But after a Week Batteries where emtpy.
So i had a detailed look at the Node.
The PIR Module has a 3V regulator on Board, which seems to be designed for 5V input.
The Batteries only provided ~3,9V wich resulted in ~1,4V behind the regulator, but the Module was working properly.
So i decided to remove the regulator from the PIR Module and power it from 2 AAA Batteries (providing ~2,4V input).
Additionally i removed another 3,3V regulator i was using for the nrf24l01 Radio.
Now the Power consumption is down to ~0,2 mA while sleeping (ATMega328+NRF24l01+Pir Module) and ~15mA when awake.
Running without Problems since 2 Days.