What wattage are you vaping at?
Current can be calculated by dividing the watts by resistance, then taking the square root. So if your coil is 0.8 ohms and you're hitting it with 40 watts, your amp draw is
sqrt(40/0.8) = sqrt(50) ~ 7.07 amps. Even if you have a 3000 mAh battery (which they don't make with amp limits high enough for the IPV2, to my knowledge) it would only last 3/7.07 ~ 0.424 hours, or 25 minutes pressing the button continuously.
Long story short, even moderately high wattage vaping requires having spare batteries at your disposal. I vape at 15 watts all day, and often need to change my 2900 mAh battery near the end of the day. The IPV2 probably requires at least 20A continuous batteries, and they're hard to find with high capacities; they just don't really exist, sadly.
The calculation isn't 100% accurate, but it lands you in the right ballpark for amp drain. It actually overestimates how long your battery will last, pressed continuously.