:/, hard to tell, knock off Ego Style battery, voltage can be 3.4v or it could be up to 3.7v, then you would need to know the resistance of you
tank coil, lowest most Ego batteries can handle is 1.5ohm lowest, but average at around 1.8 to 2.5ohm in a basic plastic clearomizer, knowing those figures, the formula is voltage X voltage / resistance (ohms) = watts.
3.4v X 3.4v / 1.5ohms = 7.7067watts
3.4v X 3.4v / 2.5ohms = 4.624watts
3.7v X 3.7v / 1.5ohms = 9.1267watts
3.7v X 3.7v / 2.5ohms = 5.476watts
4.625 to 9.13watts is your approximate range depending on your Ohms and voltage the battery puts out.