You can't fry a phone because the power bank has too much capacity. Your house wiring has a capacity of 200 Amps, but a 100 Watt light bulb attached to that power only draws 1 Amp. (Devices draws what they're designed to draw - as long as the voltage is correct. Since the power bank is almost definitely 5 Volts (nominally - it can be 5.2 or 5.3), it will work fine. (I use a 7,500 mAh power bank myself. I recently used it as an uninterruptible power supply for 3 weeks with no problem. [Power bank plugged into the wall, phone plugged into the power bank. If power failed, I still had about 24 hours of actual use of the phone left.[)