Here's a formula: P=E^2/R
Funny you should say that, @crxess. Looks like since my battery is 10w max and my coil is 1.6 ohm, even when I set it to 4.2v, it's most likely really only putting out 4v. (Found one of the online calculators btw @Fuzzy Thunderbear! Pretty handy!)4.0v would be a safer setting.

