I tried the new ego-c batteries and IMO they got too hot too fast because of the small form-factor of the ego battery . I have a Joytech mod tube that takes a 18650 battery and I think that would have been a better form-factor for a VV mod . I really like the design of the Joytech mod tube but too bad that an ego booster won't work on it even though it is a PWM mod like the ego batteries . I guess if you don't chain vape too much they are OK but just OK . A 650mah ego-C is as long as a 1000mah ego battery and with VV does not last as long as an ego 650mah battery without VV although it does last long enough I suppose considering it is VV .