The T3D is the most basic of dual coil series tanks that use the same coils as the Evod2, Evod2 glass, Protank 3, Mini Protank 3, the Aerotank series, the Genitank series, and the Aerotank turbos....if you're having good luck with those coils than consider yourself blessed because many of us had nothing but problems with them, myself included,,,maybe using them in the cheaper tanks like the T3D is the "magic" solution
Anyways....ego charger's have a little chip in them to take the current from the wall wart and convert it down to 420 mA, or .42 amps from whatever amperage the wall wart converts the current from the wall socket it takes in. Ego batteries are meant to be charged at this current and can't handle a faster charge...some older style ego batteries had an even lower charge current of....i can't remember exactly off the top of my head, but it was like 200 or 300 mA. The reason why they take so long to charge is because eGo style batteries now days have a much higher capacity than the older ones. It only takes a couple hours for a 650 mah or 900 mah ego to charge from a 420 mA current where a 1300-2000 mah battery is going to take that much longer and it's no surprise that it takes several hours to charge because of the huge increase in storage capacity.
Sorry, but it's just the way they were designed....although, it was recommended on the older "twist" style eGo's to set the voltage setting to 4.2 before charging to ensure the fastest and best charge but I am not sure if it matters on the newer design.