Okay so Im relatively new to vaping and Ive been using a G-priv with a tfv8 tank for a few months now and it has two Imren 30A 3300MAH IMR 18650 3.7v batteries. I usually vape from 100w to 130w and it keeps having this issue where it says weak battery on the screen when it still has 75% - 90% battery life left. I wouldnt find this a horrible issue if it wasnt so inconsistent. On some days I cant even vape at 90% battery but some days it vapes all the way at 35%. Please explain why this is happening and what I can do to fix it