Mine as two black up/down buttons and a red on/off button, + fire button. You are correct, my battery does not have a nipple top, so its not a true AW. I'm using a inline voltage meter from mad vapes. The drop in voltage is both measured with that, and I also can totaly notice a drop in vapor and over experiance as the battery wears down.
I do have a new battery on order, might not get it until wed/thursday, then I'll be able to tell if the battery causing my issues.
If your using an Inline Meter and you notice a Vapor Fall-Off, I would say you are getting Accurate Readings.
When you get your Other Battery, Please post if there is the same Voltage Fall-Off. I'm curious to see if it changes or not.