I know I saw a conversion chart on battery level to percent of battery left, but I am coming up empty on my searches. I am running a Vamo V2 with Protank 1.7 coil vaping at 7-7.5 watt. I have noticed when battery left gets to 3.8 that vapor drastically drops off. I am trying to figure out if that is normal or if it's due to battery being too low.