As many of us experienced, there is a known issue with the battery, which drops from X% to 0% randomly .
Just to let you know, my current firmware is KitKat, which is the latest.
I chatted with Motorola Technical Support online. The technician suggested me to change cable/user original Motorola charger.
When I said that I've tried this already and both options didn't helped, he suggested me to clear Cache Partition as followed in this guide by the company:
(It's for Moto X but works the same on Moto G)
So far, after 4 days of use, I didn't experienced this problem again, hope it's solved forever.
I hope this will help many others too,
Thanks and sorry for my english.