Hi wdave,
The other thing to watch out for is not overfilling the cart when topping up. All the liquid should be held in the cart fibre, not "pooled" on the top, With some e-cigs this "pooled" liquid can leak into the batteries and cause trouble.
Ditto. I'm guessing that overfilling and liquid leaking into the battery is the most likely culprit.
Too add to e-pipeman's excellent suggestion, one of the things you'll notice after you've been topping off for a couple of days is that the fiber inside the e-cig doesn't seem to hold the liquid quite as well, and so pooling occurs even when you haven't really added much liquid at all. And sometimes when it doesn't look like it's pooling, if the fiber is too messy, the liquid seems to drip out too quickly and fouls the atomizer (and, by extension, the battery).
When your fiber seems to have lost its "newness," and doesn't seem to hold liquid as well, you'll want to remove the fiber, rinse in water, then thoroughly dry with a paper towel. (I squeeze the fiber in between the paper towel, moving it after every squeeze, until it gets to the point where when you press down with the paper towel, no moisture stains the paper towel and it remains dry.
From that point, you can follow instructions regarding refilling/restuffing carts. (Tons of information on that in the stickies up top in the newbie forum.)
For me, I can go through one or two cleaning cycles before the fiber isn't worth messing with, and I start over with a new cartridge or restuff with new fiber.
Anyway, I mention this because I messed up a few batteries when I first started.
