All I have ever done was use a power bar with surge protection on it. That way if it dose spike it won't blow the crap out of your phone. I way using a 5000 watt. Hope this helps
Check your phone charger and see what it is rated for, if its rated for 100 to 240 volts it should be fine. The charger acts as a reducer.
I found this online. Hope it helps. Good luck!