I have recently increased my single coil builds to average about 1.5 using around 8 wraps with 28ga wire. It seems like my batteries aren't lasting as long as they were. Is that possible? I'm a heavy vapor and will use more batts if need be, just curious if going through 2-3 efest 18650's in a day of heavy vaping is the norm with a build like that. Thank you for any responses.