I'm not a huge fan at recommending non-replaceable batt systems to ppl who already have had them... but...if you *need* to have a sleek, sexy small-batt system on the go, try using an SD keychain. Click my name, I have one as my profile pic because I love it so much.
They go well with stainless-steel cartos and drip tips, and you can also use just about anything else with 510 threads with them. Carto's are great for a no- nonsense, non-fiddly vape when you're out and about. Good Luck!