Use steam engine put ur battery preset in use unregulated and it will tell you i got a buster im runnin a 35 amp subohm cell battery with a tobh atty at .3 and it handles just fine i know guys who use imren 40 amp and go down to .03 ohm builds on mechs and they run perfectly fine so just be safe bro i havent went below .3 i got a double macro coil build it blows clouds