When I got this mech, I actually just took it away from my roommate because he was an idiot and was gonna blow hisself up with it. The battery he had was an Ijoy 20700, falsely rated at 40 amp. I did not trust it and used an 18650 with a sleeve. This worked but not really a decent vape. Drained the 25r pretty quickly. I bought me a couple Samsung 21700's that I know are 35amp from liion wholesale. Built a couple plain 22ga kanthal coils with 9 wraps on 2.5mm. Right at .21-.22ohm. Huge difference a good battery makes. Never really enjoyed vaping it till now. I dont know how old this one is, the geekvape website shows pics of the tsunami but there is some kind of ring on it that mine doesnt have. But, no matter, I got everything working like its supposed to. It kicks hiney right nicely. Between this and the dovpo variable voltage mod, my poor voopoo drag is kinda collecting dust right now. It's still fairly new too, so I feel kinda bad about that. I'll put it back in rotation eventually. But for now, I'm quite pleased with the tsunami. Quite.