I have just purchased a 12v adapter with 2 USB sockets. It states under each socket 2.1a. - 5v. I bought it for charging our iPhones and iPads through the night. I am thinking about connecting it to a live feed in the rear bedroom. Would charging two items at once put much of a drain on my 2 x 110ah batteries when not on EHU. I do have a solar panel. Thanks.