Why are you posting in a cloud chaser forum. Users here are well above your skill and knowledge level. You should really keep your OPINIONS in the beginners threads. I will say, anyone using Efest should not be in this thread either. There is a very good reason why we don't use rebranded batteries, and if they don't know it, they shouldn't be here in this thread. It should be noted, that we have mentioned several times, that this is an advanced thread and new users should NOT try these builds. Reading to gain knowledge is fine, just don't try it until you KNOW for sure that you know what your results will be before you even build the coil. You should know how many amps your coil is going to pull, how many watts power you will get, how long you can fire the coil before your battery heats up, the internal chemical make up of your batteries, how many vent holes your mod has, what the result will be if your battery does go into a thermal run, and MOST important, how to build coils without shorts. People in this thread don't even use those eleaf ohm meters you get on fasttech for $8. 0.04 ohm accuracy is NOT acceptable for our purpose. So to restate, this is a thread well advanced of your vaping level, please take your opinions elsewhere, all you are doing is coming across sounding like a noob. We know the risks, and we know how to minimize those risks. Probably far better than you do.Going that low in a single battery is dumb and people that do it should feel stupid.
Parallel boxes exist for a reason. Leave five amps of head room in each battery. Go ten below what your total amperage is. If your going to use Samsung 25rs use 30 amps as your cap. You can get 0.14 ohms on a pair of parallel batteries.
If you use VTC4s or VTC3s (AKA the only real 30 amp batteries) you can get 50 amps (60 amps total out of the parallel batteries minus 5 amps per battery) and go down to 0.084 safely.
Don't be stupid. Don't do dumb things like try to draw past the C rating of a battery. Those guys are going to blow a hand off one day. Or look like The Dark Knight's version of Two Face some day.
Also, stop buying Efest batteries. Don't support those parasites.