I have a product which is powered from main AC power. I need to serial communicate the product with a computer, for example sending some bytes to the product by the terminal program in the computer. I have a USB-to-UART converter to communicate with the product. However I worry that the AC power from the product will damage my computer's USB port. If I am using a laptop computer powered by the battery (not the AC main), do I still need a USB isolator to connect the USB-to-UART converter to my laptop computer?
Please provide reason instead of just answering yes or no.
Thank you very much.