I have a BlackBerry Travel charger (looks similar to the iPhone wall charger) that plugs into the wall and has a USB output to charge a phone. The power output on it is 5V and 750mA. The iPhone wall charger specs show output of 5V and 1A. Does anyone know if I can safely use the Blackberry one to charge the iPhone? I'm assuming since the current output is lower it would be safe but possibly take longer to charge.