I got my new VAMO a few days ago, and had to wait on the batteries, which came today. Popped a battery in, clicked 5 times, and the unit powered up. Yea! Was able to set RMS, change to Watts, and set it to 6W, for my first mod vape. Yea! Screwed on and eVod, pushed the fire button... nuthin' Screwed on a 510LR carto, pushed the fire button... nuthin' Unscrewed carto, then battery... repeated above. Same. NOT Yea... voltage check on Vamo reads 4.1 510 connector looks fine. Sigh... Is it the VAMO, or do my cheap Ultrafire batteries not work with this? They (both) DO read 4.1v before I attach anything. Batteries are Ultrafire BRC 18650. They SAY 4000mAh. So sad. Back to the Twist, to vape away the blues.