UPDATE. The Meloson has been updated and now has a slightly longer battery life. This is due primarily to the ability to turn off the backlight on the LCD display. Yay!
I do have a DC to AC inverter that has a USB plug, but it is inconveniently located on the fascia of the lower bunk. Considering that at any one time I would have at least two or three USB powered devices I have decided to add an additional combo 110v and USB outlet.
Newer Technology and others offer this outlet to solve most homeowners' problem of having too many cables and not enough plugs. For about $15.00 you can replace a standard 110v outlet with one that also offers two USB ports. I chose this one because it has technology that senses a full charge and cuts off the USB power. Hopefully preventing any damage to my devices. The additional two 110v outlets will also solve the problem of having my only 110V plugs adjacent to the dinette/bed.
UPDATE: The Newer Power2U has one major drawback; some larger power plugs, and most all wallwarts block access to the USB ports. I may suggest sacrificing one of the 110v outlets and going with one of these... http://www.amazon.com/Cooper-Wiring-Devices-TR7740W-K-Combination/dp/B007NC5GI4/ref=pd_sim_hi_2?ie=UTF8&refRID=0XPR97X5XFFTS1BFYNBK
Welcome to 2018 and USB 3.0 and High powered charging.
I have decided to upgrade my USB /AC outlet with a newer one capable of charging USB up to a full 2.4 Amps. Apple's new iPhones, and a few other devices that offer high speed charging can take advantage of the higher USB power. Charging twice as fast as before.https://www.amazon.com/gp/product/B00IAZIU5Y/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1