Can someone please tell me the maximum charging rate for the 521? The reason I want to know is that I am looking to buy a micro USB "car charger" and I want to know if there is any advantage to buying a charger with output greater than 1 Amp which is the output of the Nokia DC-17 car charger. I can buy a dual-port car charger that has an output of 4.8 Amps (it's actually intended for tablets), but I don't that there's any advantage of having such a powerful car charger if all I'm charging is my 521. Thanks.