vv = variable volt (has a dial on it to "tune" the voltage).
Basically, mods are either regulated or not. Regulated means that they try and put out a constant voltage by some means. For example, the eGo type mods are regulated around 3.4 volts. Other "all mechanical" mods follow battery voltage. I use regulated 5v box mods. vv's have a variable regulator to "dial" voltage. The little "super mini" e-cig batteries put out about 3.2 volts.
Measuring the voltage, OTOH, is tricky since it needs to be done under load (atty attached). This is done with a test rig that has wires for a multimeter to clip on to to measure the voltage.
There are pros and cons to each. I'm not saying any one is necessarily better than another. The trick, with any e-cig is to "get good at using it". I'd guess, that since your mod is stated (in your 1st post) to be 3.7 that it follows battery voltage... that is to say unregulated. Just a guess. That's OK... I've built several of those myself. It could also be regulated to 3.7. IDK.
Basically, Li-Ion batteries come off the charger at 4.2 volts, drop quickly to around 3.7/3.6 volts and more or less stay around that voltage until near the end where they drop off fast. Then, protection kicks in and shuts off the battery before it discharges too low. The AW IMR batteries put out a lot of amps and that helps them maintain their voltage during higher loads (like when using LR atties/cartos).
So, check with the manufacturer to see what type of mod it is, or check on this site for reviews/specs if you can find them. I like all mechanical mods, since there is less that goes wrong with them....particularly if they have a replaceable button. Regulated is nice too, since it is a bit more consistent vape. Mods using two batteries frequently have regulators (adjustable or not) since they want voltages higher than 3.7. Some are stacked HV mods ..no regulation. You just have to know.
All are usable and work fine. I'd suggest reading up here on ECF regarding battery types, mod types and safety. Single battery mods are generally considered safER than stacked battery mods... but all can be fairly safe if understood and used properly with the proper hardware. See ECF's battery safety info and tube-mod guidelines for info, and talk to the vendor for more info. Use protected batteries where possible, particularly if you stack them, and don't over-discharge them if they are not protected (I'd recommend protected batteries in general).
There's a learning curve to e-cigs... and a lot of information overload. It's normal. And you don't have to know (or do) everything at once! Keep on with the good fight!
