I just purchased a variable volt vaporluxe, it came with a USB charger without a wall plug. Charging from my computers USB port is not always convenient. I have several wall plugs with USB ports from other ecig models. They all seem to have 110v input and 5V 500mah output. Is this the same power that comes out of a computers standard USB 2.0 port. Will I damage my unit by using one of these wall plugs that has a USB port?