Sorry guys for the necroing here, but i feel there should be some justification happening around the Efest 3100mah battery. Too much paranoia has been written about these
batteries, and almost exclusively people have been quoting 1 person (i say ONE person) test results. I myself fully believe the 3100MAH batteries are great batteries (i use them in my DNA 30 mod but have been using it in my mech too) and people shouldn't be discerned buying them because some - scared to death - people don't advice them. Look if you are really in to sub ohm, go for Sony VCT4/5 (or Samsung i guess) but most people should get plently out of this battery.
I have vaped 0.5 ohm with this battery and it didn't heat up (in a mech mod with the magma dripper). I have seen several unwrapped efest batteries, NONE were rewrapped batteries. After reading so much in to it (as i myself got scared reading some topics here) i really came to the conclusion that these batteries are safe, prob have 20a continues discharge and can easily put out 35a pulse discharge (which is really the only thing worth mentioning when talking about
vaping). For your VW/WW mod, this battery BEATS Sony's battery (from my own experience), for Mech mod its okay but VCT4 (or 5, i own 2 4's), would probably be better. Heck i'm not even sure about that. Anyways as i have read, these batteries can put out waaaaaaaay more then 35a PULSE discharge (though only for a few seconds, but them again that is what we do!). No one is firing their mech mod for more then 30 seconds (hell 10 seconds prob max and that is one heck of a lung inhale). Most of the time its a few seconds and i fully believe this battery can take it. Why do i say that? Because i own this battery for a few months now, nothing happened.
The biggest issue i think (also what that German dude from that website probably had) are FAKE Efest batteries. I think if you unwrap it, and it aint a clean tin colored battery, but a rewrapped one, you my friend have a fake one. People who only got 3a or w/e out of this, probably had the panasonic one and not a 'original' efest.
And at last, do NOT read to much about this battery, because you will become as paranoia as the folks who are scaring people away with their nonsense (there i said it). Yes safety comes first but people come with no real evidence trying to claim things they haven't experienced themself. Let the first one come whose battery got vented (with evidence showing it wasn't his fault like a faulty mech/way to low ohms etc) and i would agree. I mean this battery lasted me the day (from 11 am to 9pm exclusively), the VCT4 doesn't last that long.
p.s. i am NOT an engineer or some sort (actually i am in the healthcare lol), so you don't have to believe my word. All i am saying is don't believe the german site either, because that test/battery was bogus (bogus i tell ya!) and those who used the Efest battery pretty much ALL only have positive comments (well besides the few 'VCT4 feels like it hits better' comments).