It's not the circuitry in an eGo battery that does anything much for you - other than (in theory) popping open a circuit that renders the battery useless if it's charged to over voltage. The charger itself is, after all, a charger. If you are using genuine batteries try to stick with a real Joyetech eGo charger.
When you hit off brand batteries you have to be careful and only use the charger that came with it. There are a lot of crap blister pack batteries out there that include hacked battery designs and not much more than a USB to 510 adapter with no actual charging circuit in there at all, other than maybe a voltage dropping resistor. You know those scare stories you see about batteries blowing up? Yeah, they almost always involve a cheap knockoff eGo battery and one of those non-chargers getting mixed and matched with other batteries and chargers than what they came with. They are trying to rely on the internal eGo battery high voltage safety cutoff to act in place of a legitimate charger - and that's just wrong.