I have been watching Congrevape way too much lately, but they have the Sony 18650VTC4 2100mah 30a batteries back for another group buy. I personally love the VTC3’s and use them as soon as I get home. They have a great output, are as safe as can be, and have a great casing. I’ve had other battery casings get ruined on me, creating unwanted contact with the mod, but these are tough. They aren’t the cheapest batteries, but they definitely are the most sought out.
Get them here before they sell out again (4 for $30.85). http://congrevape.com/projects/sony-18650vtc4-2100mah-30a-2/