I've been an eGo user since Dec 2013. I've *always* had issues with their coil QA (Quality Assurance) bc I could buy a 5-pack of coils - no matter which tank or coil I had at the time - and at least 2 would burn out or otherwise be defective.
At the suggestion of a very good (& knowledgeable) friend, I ended up slapping a Kanger Subtank Nano on the eGo ONE battery... OH. MY. GOD. What a difference!!!
I'm very clumsy so I've dropped the eGo ONE battery many, many times on various surfaces (concrete, asphalt, ceramic tile, stone tile, linoleum) and even took a couple HARD falls on concrete... it's always performed like a champ afterward..
Then I totally screwed up without realizing what I was doing... While moving Saturday, I not only accidentally knocked over my Nano/eGo One vape into my porcelain-coated steel wall-mounted sink & chipped the glass of the tank, but I also inadvertently dropped the damned thing on my old concrete driveway later & smashed it... what I SHOULD HAVE done was immediately remove the tank. Instead, I flipped out, drove the 10 min to my new place & then replaced the tank (thank GD the Nano comes with a replacement tank).
Everything seemed fine over the next 12+ hours.. then my battery died. I fixed it but my OCD kicked in & I just *had* to perfect my work.. which resulted in a jammed button.
Now I have to replace the battery. There are only 2 B&Ms in my area. My preferred B&M has some serious .....es running it (employees - I love the owners) and the other one is closed Sundays & Mondays. *sobs*
TLDR: eGo ONE battery (2200mAh+) with Kanger Subtank Nano = OMGAlmostO-FaceTime. The batteries are beasts & extremely durable but if you accidentally smash a tank, remove it IMMEDIATELY to prevent juice from leaking into the battery and killing it. (DUR - I should've known better!!)