As you can see from
@conanthewarrior post above, you are potentially operating at a current well in excess of the true continuous current rating of a Sony VTC6 battery which is 15 Amps. Mooch tested this battery and rated it for 19 Amps continuous, but I always recommend staying within the ratings provided by the manufacturer, for they take into account manufacturing tolerances, etc. I personally like more margin to account for an aging battery and use 80% of the continuous current rating.
Here's what Mooch said about the Sony VTC6:
"This is an great underrated cell that I am rating at 19A/3000mAh. The datasheet lists the max continuous current at 30A but that's only if you stop the discharge when the cell reaches 80°C, way before a continuous discharge has finished. The true continuous current rating from Sony is 15A. But at that current level the temperature is 72°C, about 6°C-9°C cooler than other batteries at their rating. This is why I feel it is underrated, like the Samsung 30Q, and why I have given it a 19A rating. It runs at a slightly higher voltage than both the 30Q and HG2 though."
Your case is a perfect example of why Resistance DOES matter even in regulated mods.
A few things to consider:
1. Resistance should be within the mod manufacturers range for power (watts) or TC mode. (This assumes you have a battery that can supply the current for the power you are vaping at!)
2. Resistance of the coil you use often has a bearing on the Power (watts) setting you want to vape at, and the power setting should not cause your battery continuous current rating to be exceeded. For me, that means 0.8 times battery continuous current rating, to allow for degradation due tobattery aging, I'm a conservative engineer
3. Resistance of the coil can limit the power you can vape at. For an Evic Mini with a 1.8 ohm coil, you're not going to be able to go higher than 45W, even with 75 Watts selected, since the maximum voltage the Evic VTC mini can provide is 9V and P=V(squared)/Resistance. So yah, resistance does matter. (I know, no one would vape a 1.8 ohm coil at 45 Watts, but this is to make the point, lol).
For mod efficiency, the few ratings I've seen are a little better than 85%, so I've used 90% (0.90) in my calculations, but nothing wrong with being conservative and using 0.85 since the manufacturers rarely provide the efficiency rating.
If your battery is at 4V, I=P/V/Eff = 75/4/0.85= 22 Amps.
If your battery is at the "battery low" alert voltage of 3.3V for the Evic VTC Mini, your current is at. 26.7 Amps. (mod should lock and not fire).
I never try to count on a manufacturers "protections" to protect me from using the wrong battery for a given power level, the formulas are quite simple.
So, can you run a mod at 75W using a single Sony VTC6? You proved you can, at least for a while, but its gonna get hot. How hot is your battery? Answer, we have no idea. Should you? I think absolutely not, IMR is a very reputable company, and they sell the VTC6 as a 15 Amp battery:
https://www.imrbatteries.com/sony-vtc6-18650-3000mah-15a-flat-top-battery/
This is a great battery with conservatism built in at the 15A continuous rating, so I would have no problem running it to that rating.
