I had this problem at first, as well. My first hit went from ?? to 85% on both batteries their first time being used (AW IMR 18650s 2200mah).
As others have said in this order:
1. Stretch the endcap spring
2. Clean the male and female extension ring's threads like a needle on a record (I used a baby bottle brush - you can get a very little one at Michael's in the baking section for under a dollar - and it comes in handy for cleaning tanks also, but you could use a toothpick or razor blade)
3. Wipe the threads of the extension rings with a paper towel dipped in rubbing alcohol
4. You can then add a small drop of No Ox to each of the threads (optional)
5. Be sure that your extension rings and endcap are screwed on tightly
My threads were definitely dirty from what I saw on the baby bottle brush (and the tooth pick until I lost my patience and grabbed the brush).
Now, after draining and charging my batteries, I get about 99% battery life after the first hit. I'm running 14 watts/4.5 volts, with a 1.5-1.6 ohm coil on a Kayfun Lite + v2. I don't use Boost (personal choice). The IQ is 88 and up.
I put in a new battery about 26 hours ago, and still have 51% battery life showing (and I honestly take 2-3 toots every 15-30 minutes - sometimes more - which I consider heavy
vaping, although I'm sure that others would consider it light).
I'm
beyond pleased with the battery life now. I've had other mods that only lasted 24 hours or less with the same basic setup while using a lower wattage/voltage setting.