Why is my Lumia 520 battery draining too fast? At 4.00am when I charge phone to 100% within an hour it is completely drained to 0%.
The simple truth here is that the Lumia 520 has an extremely small battery in it. The battery in the Lumia 520 is 1430mAh which is considered extremely small.
The other thing is that the Lumia 520 still runs on Windows 8 Mobile.
So those are the two factors that cause your phone battery to be drained so fast. There's nothing you can do about this. You either need to buy a new battery for short term better battery or buy a new phone for long term better battery.