Hello,
Did you try an OTG cable with a micro USB Female charging HUB ? (like this one http://dx.com/p/micro-usb-male-to-2-port-usb-2-0-female-1-micro-usb-male-charging-hub-black-243246#.Uw5aOvl5Oxl)
With this cable you may at the same time connect the power supply and any USB device to the Dell...