I'm getting my first device with removable batteries in the next couple of days so I started doing a little research into the various batteries, battery drain, draw, current, amp ..... *brain explodes* Ok, so I got more than a bit lost. I would like to know how to work out which batteries are right for a particular mod and whilst I was looking I came across this: W+(W•.1)/V = A W =watts selected V = the mods low voltage cut off under load A = battery draw Perhaps somebody could explain it? Also, when using the battery drain calculator on Steam Engine, which results do I need to be looking at? Could someone explain what I need to know regarding continuous maximum discharge current and maximum discharge current. I would also like more specific advice. I'll be buying a 200w device. I will rarely be using it over 100w but I would like a battery that enables me to get the most out of the mod if I choose to. Should I buy two different types of batteries for different styles of vaping? This is probably a silly question. Do I need 20a or 30a batteries? The mod I'm looking at comes bundled with two Samsung 25R's at an insanely reduced price but I'm unsure they will be adequate being 20a. I was initially looking at Sony VTC4's. Last but not least, flat top or button top?