I'm guessing, by the shrink wrapping, that they are custom made from a place that makes custom packs. I think the chargers for them are Lithium chargers that are modded to take nimh batteries. Most likely, your only bet would be from an online cig shop like Electronicstix.com, Madvapes, Nhaler, or CloudsOfVapor. They have double battery chargers that recently came out, so I'd pick one of those up also because they take 6 hours to charge. They work perform pretty well, and should last for the day, but you wanna grab a few of them.