Yup, it is 3.6v. At first, I wasn't sure I liked it, but it's pretty nice. I emailed the designer and we had a little chat about how it worked and I like the algorithm it uses.
To figure out what size PS you need, you can use
this page as a guide. The table below is for the Xtrema:
Code:
Input V Min A Safe A
11.0V 20.5A 25.6A
11.5V 19.6A 24.5A
12.0V 18.8A 23.4A
12.5V 18.0A 22.5A
13.0V 17.3A 21.6A
13.5V 16.7A 20.8A
14.0V 16.1A 20.1A
14.5V 15.5A 19.4A
15.0V 15.0A 18.8A
It's obvious that a higher input voltage will require lower current so try to find a PS with a solid voltage. Most dip down once you start drawing some heavy current...