Looking at those "speaker" grills on the dash of the ST gave me an idea. Once again the many vendors on Ebay came through. I found a dual USB power hub and voltmeter in one unit that fit the outline of the grill pretty well. Installation was simple AFTER getting the bike naked. I used the mounting bracket as a template. I believe my hole saw was 1.25" and worked perfectly. Both the USB hub and the voltmeter are wired to the fuse box I installed under the passenger seat. The fusebox is powered through a 40amp Bosch relay that closes when the bike ignition is on. The power to activate the relay comes from the "relay" side of the bike. I googled accessory power ST1300 and found a page on st1300.us.com that did a great job of explaining it all with great pictures too.