I never used the 3000 mAh batteries but I only got a few hours more out of my 2400 mAh ones than I do from my 5V with 750 mAh 16340s. I think the mAh ratings on some of these batteries is wildly exaggerated. I used the Ultrafire 18650s (grey ones) and I was chain vaping for about 9 hours before they got too weak to be of use.