I can assure you that My E-Power 14650 is regulated to 3.7V. I measured voltage at the 510 connection with no load.
Battery voltage: 4.15V
Voltage at 510 connection: 3.66V
Battery voltage: 3.62V
Voltage at 510 connection: 3.62V
I am using the latest of several E-Power 14650 switch modules that have been produced. This switch module has a hard plastic button, blue LED button light, 5-click switch safety and operates LR cartos/attys down to 1.5 ohms.
It could be that earlier models of the E-Power 14650 switch were not regulated.
Why is regulated voltage a good thing?
The 14650 battery lasts me about 24 hours or two ml of juice. This is a very consistent run time. Some days the battery lasts me a couple of hours more, sometimes less.
A freshly charged 14650 battery is somewhere between 4.13 and 4.19 volts on my chargers. No matter what the voltage of the battery is between 4.20 and 3.66 the E-Power 14650 shows 3.66V at the 510 connector. In practice, 95% of the time my batteries are between 4.19 and 3.66V, meaning I get a nice consistent vape of my LR carto for about 22.5 to 23.0 hours. When battery voltage is below 3.66V the voltage at the 510 connection is equal to battery voltage and falls off quickly. I found that my E-Power 14650 with a 2.0 ohm LR carto will only run lower than 3.66V for 60 to 90 minutes before the battery falls down to 3.2V. At 3.2V the low battery signal flashes and the E-Power 14650 will refuse to fire soon afterward.
Does my E-Power 14650 deliver 3.7V (3.66V in the unit I tested, no load) under load? I don't know. I don't have DMM connector to test for that yet. I suspect it doesn't and you need a more sophisticated (and expensive) APV to automatically maintain a regulated 3.7V under a wide variety of possible loads.