Originally Posted by
zkyevolved It's always good to keep at least 50% battery in your device while writing to the firmware memory. It really depends on the device. Some ports / hubs don't supply enough power to the device while transfering. So it uses the devices battery. An excellent example would be the iphone. While on USB and using the device (screen on), many people complain at least, that it actually dies while charging via USB And using it. So, while updating roms, keep 50% just in case :P.