Digi has a new product to address this need.
Digi PN: 76000976
I have it running in the field for about a month with any issue.
This setup worked great while running in my workshop, but once put into service in the countryside, the WR11 went dead after about a day. My best guess is the cell signal is weaker/different in the countryside and the WR11 might really pull some big power at times, more then the USB charger can supply. Now that the days are longer and the rain has gone, I have moved the WR11 back to AC power. I will continue to work on this project to get ready for next winter when I need to use power judiciously.
I have a remote hobby ranch that I monitor over the cell network. I have found the Digi TransPort WR11 XT to be a solid way to get a connection to the cell network for sending logging data back to a central server. Long story, but in the end running the WR11 on AC power was not good situation as the primary power is a 24V solar system. It ends up the most difficult part of the project was tracking down the special locking barrel connector Digi uses. After ordering a handful of connectors, paying shipping, and waiting after each to arrive and not fit, I finally found the right one:
Mouser PN: 806-KLDX-PA0202-B-LT
Below is a cable I made with the locking barrel connector.
Specs say the WR11 can use up to 15W of power, so to run on my 24V solar system, I used a 2.4A 12V – 24V cigarette lighter style auto USB charger. I run on one SIM card and find the power usage stays under 3W. Time will tell if I will need to find a beefier USB charger, but so far so good. So if you find yourself trying to run a WR1 XT on DC power, the connector PN above may save you the time, hassle and money I spent.