Dudeman is right about the LR not drawing more current from the USB port. That said, however, I would still use caution when plugging into a computer port. Even regular 510 PTs, with the battery box, have fried some ports in my experience. This depends on the charging current, and even to charge a battery, some draw more current than the port can handle. Always best to use an external powered USB hub or AC/USB converter with any PT. The exception might be the Sit and Go PTs, which use only 300 mA to charge. Most computer ports are rated to only 500 mA. I have also fried cheap USB cables with some PTs, like the Bartleby. If the battery charges very fast, its convenient, but drawing a fair amount of current.