Even at 75 watts, I don't think 0.19 ohms should drain a battery with just 2ml of liquid being used. It's only pulling 19.8 amps / 3.7 volts.
I mean, I'm currently dripping on a 0.18 ohm rda @ 90 watts and I will go through 10ml+ of liquid on this pair of batteries. Pulling 4.1 volts / 21 amps. I'm drawing more power and the 2 batteries will last more then 5 times longer then your single battery, and they are only 2500mah batteries vs your 3100. I'm using new Samsung 25Rs though, not eFasts. My old Samsung 25Rs would die after only 2ml of liquid, but they were 6 months old, they stopped holding a charge and my sigelei would think they wee dead when it still reported 40% charge.
It could be a few different things, or any combination of them.
-The internal charger may not be charging the battery fully before thinking it's full (defective mod). Only way to test would be with a different mod.
-The internal charger may not be capable of fully charging it due to manufacturer limitations. Only way to test would be with a different charger.
-The battery may be defective. Only way to test would be with a 2nd battery for comparison.
-The battery may not be as good as the manufacturer specs claim. Would need a battery from a different company to compare.
-Maybe not giving it enough time to charge. The internal charger may be very slow and the battery is 3100mah, might take a lot longer to charge then your expecting. If the charger can only charge at a rate of 200mah, it would take 15 and a half hours to fully charge a 3100mah battery.
I should note though, that my experiences and info is based on non-TC setups using kanthol.
I imagine things will be different on a TC setup.