I知 going to update my icharger 4010 but I知 not sure if I have a shielded usb cable so I need to power the charger by a battery, my question is what size battery can I use to do this?

straight from manual.Input Voltage 9 - 50V DC

I just updated my 4010. I didn't really read the instructions, just connected a USB cable to the computer and had the Junsi updater do it's thing. Worked fine. Charger powered off my normal power supply. I guess there's a risk that if you loose power during the update process you could brick your charger.