I'm not sure about the 901, but my 801 flashes 15 times slowly to tell me that I'm
vaping too much and it's cutting me off for a while. It and I seldom agree about this, so I've pre-ordered a Prodigy. I refer to the microchip inside as the "nanny chip."
It flashes 20+ times quickly to show that the battery needs charging, and it flashes four times to show that it's plugged into the charger. The charger also flashes green - just a blip - every five seconds after it's charged for a while, but I haven't figured out yet what that means.
Maybe the 901 does something similar?
It also seems to think that I puff in a strange way. If I make a slow, steady draw, the LED glows and fades, glows and fades, and never goes nanny on me. I also have one battery that is fair more stringent than the other. Open the pod bay doors, Hal.