I use 1.5 ohm atty's on my mods. When my batt's first come off the charger they're around 4.2v. That'll produce around 11 watts which is just under the point where you'll burn most juices. I usually recharge when my voltage drops to around 3.9v. If you like a strong TH and lots of vapor the combination of 1.5 ohm's @ 4.2v is great.