You gave me a few ideas actually as a standard sized torch uses AA batts. The 14500 batt is exactly the same size as a standard AA and is used in the little gem so should be a good batt to use

I already have my eye on an aluminium torch I might break to have a go at my own mod

I was thinking of using 2x 14500, but they are 3.7v each (7.4v overal) - using a 901 atty. I did a quick google search and found the following formula to determine power output, which is pretty useful:

P = (V / R) * V

So at 7.4V with a 5.2 ohm atty you would get (7.4/5.2)*7.4 = 10.5 watts of power

A 3.7V device with a regular 510 atty (2.3 ohm) would give you 6 watts of power.

An eGo (3.1V) with a regular atty only gives 4.2W of power.

So for 7.4V I would need to use an atomizer with 5+ ohms of resistance. My question is which combination would result in the greatest life expectency for an atty?

I found a heat produced (watts) for commonly available atomizer / battery combinations:

-Jay