11 watts is about as high as you can go with a single battery configuration. While you have it set to 13 ... you're not achieving it.
Just thought you should know ...
Yep I saw the graphs....
Just wanted to make sure I was at max power.
I also confirmed that in my case there is no reason for me to ever stack batteries.
My rba is the only device that I can run @ 11W and not have burnt taste.
At 12W (stacked batteries) it starts tasting funny.
That may be different for running dual coil atty's though.