Surprisingly, this is actually a fairly decent ecig, not to promote buying from big tobacco, but for what I paid I'm certainly pleased..and in a pinch, as long as it worked, I didn't really care. What I've figured out so far is that the battery won't even fire without a cartridge attached, it just blinks the led in a white/red pattern, so there's obviously some sort of communication going on between the chip inside the battery and the chip inside the cartridge. First step is going to be getting a logic analyzer of some sort, probably my old Arduino once I find it, and a few spare cartridges to hack up into a sniffing interface. From there it's a matter of decoding the data being transferred, and hopefully finding a way to spoof the protocol and/or reprogram whatever chip is inside the cartridges. If anyone has information on the chips being used, please feel free to let me know! I'll verify the part numbers posted in the imgur gallery linked above once I finish this cartridge and can tear it open.
Edit: Closest match found with some quick Google searching for the chip inside the cartridges: http://rohmfs.rohm.com/en/products/databook/datasheet/ic/memory/eeprom/br24g08-3a-e.pdf Markings don't all match, but it'd make sense for the chip to be some sort of an EEPROM, with the unknown chip in the battery being the brains of the operation that checks and updates the 'fill level' value on the EEPROM. Going to have to find something I can use as an EEPROM dumper it seems.