Hmm the Efest 18350 800mAH battery has a continuous discharge rating of 6.4 A. If you were vaping at 0.5ohms and (let's say) 3.7V, you were at 7.4 A. Didn't you notice the battery getting extremely hot? Doesn't sound safe to me.For 18350s, the eFest brand does NOT hold up as well as the AW IMRs.
At least on my .5 ohm coils--I've been using both for 5 months and have subsequently given away all my eFests.
This was confirmed by my ohm meter as well--under load fresh off the charger the AW IMRs were giving 3.9v, whereas the eFest were giving 3.6v.
This was using both a Poldiac and GGTS.