Dual coils, if you are using dual coils you are killing your battery life, also its more efficiant to use higher ohm stuff as it is less of an amp draw on the batteries. That said, I agree with others, 5 hours even with dual coils and LR stuff is way too light, just a comparison, I have never ran mine dead, ever, never even been lower than 40%, but Thursday night I forgot to charge my Darwin overnight as i almost always do, and it vaped all day Friday until my Opus arrived, I vaped itfor about 6 hours, and when it died I went back to my Darwin, it lasted me until I went to bed, it probably saw a good 10-12 mils of juice over those two days, but it held up just fine.