I've talked to a friend that only vape on mech mods and is experienced, helped me to buy new batteries, so i got sony vtc 5a INR and he told me 9/10 cases they turn off when they're lower then 3.7V then i've also looked at ohm's and thought about doing 0.16ohm's with a sony vtc 5a at 25Amp
Okay, I'll put it this way. You own a Ferrari that can do 200+ MPH. Now driving that Ferrari at full 200+ fully red lined on the engine everyday everywhere you go, what happens to the engine eventually????? Seriously, think about that for a bit. (*Answer=The Engine Finally Says F&&& You and Blows after such extended abuse*)
Batteries that we use follow the same principle. Lower and lower you go, the hotter and hotter in watts you get, yes. However, not just the watts being applied and amps pulled goes into how dense a cloud you get, other factors also play equal parts to the equation. Namely airflow, way it is wicked, and how that hot wet vapor mixes with the cooler air from the airflow.
Now take this into consideration, as you use and recharge batteries, they loose Mah and capacity, this is due to the electrolytes inside crystalizing and creating more internal resistance and taking molecular space to store ions. A battery's CDR is based off the Mah coupled with its actual C (or Current) Rating, if either Mah or C rating decrease, the CDR decreases. This is natural and just how batteries function, no way to get around it, but you can extend out this degredation of the internal chemistry. Because as you max out the CDR, you literally cook the internal chemistry, same principle applies to simmering a stew, add heat to any equation in chemistry you change the chemistry, so rapid high redline CDR pull builds internal heat rapidly.
So for utmost safety sake, never build, especially on a mech, over 50% to 75% of the battery's max CDR, VTC5A being 25amp CDR, that becomes 12.5amps CDR to about 18 or 19amps CDR. For under normal mid stress (50% CDR) duty, by about 6 to 12months that battery has become not a 25amp battery, it is literally a 12.5amp battery, 18amps constant duty the battery reaches that point at about the 3 to 9month range, full 25amp CDR constant duty, 1 to 3months. So optimal builds would be about 0.34ohms down to about 0.23ish ohms, though they can handle a 0.17ohm, you'll not be liking constantly buying new batteries every month or so. That leaves optimizing your build at the airflow and wicking as well as much wire to wick surface contact you can achieve without mad ramp up time, and wicking the coil to allow unrestricted air vortexing inside the RDA.
Mother Nature is a great teacher when creating the perfect cloudy storm. Hot Humid Air with dust and particulate + cool dry air + air draft currents to vortex the mixture properly = storm clouds. The key being the proper vortexing and enough hot vapor vortexing in an RDA for long enough before exiting the top cap = big clouds. Needing warmer and hotter vape hitting your mouth and lungs, choke the airflow down and make the coils wider in diameter to compensate a bit. Lower is not always better in this instance. I can get a much denser cloud at 0.8ohms using 30AWG triple parallel dual coils 3.0mm ID at about 50watts on a single battery regulated than I can with a 22AWG 5wrap dual coil at 0.14ohm at about 150+ watts on a mech. Competition clouding is another matter entirely and takes other things into consideration like voltage drop, mod resistance, peak and pulse ratings of batteries, voltage sag at pulse this list is long and in depth.
An optimal build on any single battery mech is actually about 0.25ohm, even on a 20, 25, or 30amp battery, its a little stressing on a 20amp but still pretty safe, though battery life is about 3months or so on a 20amp.
Now the issue of 3.7v the battery cuts off. In a mech, *Strike Out Buzzer* not true, a mech has no brains, keep the button down a mech will drain a battery down to empty eventually (0volts) if not careful. Take a battery below 2.5 to 3.0v you damage it irrepairably interally, so you have to be cautious there. But most people on a mech once the battery reaches about 3.5ish to 3.7volts the vape on a mech is weak and unsatisfying so you are the mod cutoff circuitry of a regulated in that sense. 3.7v is the median voltage rating, 4.2v fresh charge to about 3.9v is a rapid drop, then the charge plateaus from 3.9 to 3.7 to 3.6v gradually and slowly, 3.6 t o 3.4v is a rapid drop, 3.4 to below that is a tail spin downward from there.
I am not trying to harp, but in my heyday of cloud chasing kept always hearing lower ohms lower ohm lower ohms dude, just not true, though a 0.2ohm quad 24awg 3mm coil set up is hard to beat in the cloud department on a mech only matched by a 24awg 3mm parallel 0.2ohm dual coil (technically a quad coil 4x seperate parallel wires still) (quad coils are kings of clouds, triple coils kings of flavor, dual coils a balance of both plus run time and longevity).
Cloud chasing on a mech, you literally have to be on the ball and on your "A" game constantly, especially when pushing the limits toward maximums.
Morale of the story, can you push the limits, yes, if you keep on top of things OCD religiously, should you push the limits, "NO".