Maybe I should re-phrase the question. Ive read the sales pitch. Is it a secret? What makes it so that you can adjust the voltage? Is it just unscrewing the cap? Can I adjust the voltage on a grant by turning the cap and playing with the screw? How do you know when do you have the desired voltage....do you have to meter it each time you turn the cap? I love the idea, I'm just curious how it works.
Single 3.7v batt and spacer: Cap loose = 3.7v
2 - 3.0v batts: Cap tight = 5v - Cap loose = 6v
2 - 3.7v batts: Cap loose = 7.4v - Cap tight = LOOK OUT!
Don't know why you'd want more than 6v but if you wanna go for it....
And no the grant won't do that.