[s]The outer diameter of the barrel seems to be 5mm, while the inner diameter seems to be 2.5mm, just as dusty_nv said. I’ll look for a jack with those specs with more persistence. If anyone has found a way to power the dev kit with a battery, please tell me what you did.
Thank you.[/s]
Edit: Turns out measuring within 0.5mm is hard on a phone ruler. I think the specs of the DC plug are 2.5mm x 5.5mm. I looked up the model number of the AC adapter (GST90A19) and it has a DC plug spec of 2.5mm x 5.5mm. http://www.mouser.com/ProductDetail/Mean-Well/GST90A19-P1M/
NVIDIA has a custom GST90A19 called “GST90A19-NVDA” but I doubt they changed the DC plug specs.
We use an external battery bank to power our field prototypes. The RAVPower RP-PB14 comes with the correct cable and tip to plug directly into the TX-1 Dev board. It can supply 9-20VDC at ut to 4.5A and has 23000mAh capacity and will run all day and more.