I like small form factor mods. I know this means I need to change batts more often, and I'm okay with that. That being the case I want to get ones with the best life and highest amp rating. I'm not trying to cloud chase, I just want the suckers to last at least half the work day. I currently have ONE eFest 18490 that doesn't work in my Cartel mod, so I need some 18500's to get me through the day. What should I get?