I've caught this happening with my Poldis, where I have been vaping on a battery for too long, and it's still vaping good and hard, but gosh, it seems like that battery should have gone weak a long time ago, but it hasn't. I take the genny off it, check the voltage, and I'm down to 3.61 volts! Yeow! I swap out batteries at between 3.7 and 3.8 volts. I try not to let them get down to 3.6, but it was still vaping good and hard. So what? No voltage drop? Every other mech I've ever used would have been vaping real weak by 3.7 volts.