I am assuming the SVD measures the resistance of the coil and displays it? Check the resistance of the coil a number of times and while you vape to see if it always reads the same number. There might be a problem in the VW mode if it doesn't correctly measure the resistance time after time.
If you are only using one tank, go to the VV mode and vary the voltage and get the thing dialed in so you are happy.
Different juices take different voltages too as do different coils.
Yes, the SVD measures the resistance of the coil/coils in the atomizer head of the tank (the part of the atomizer unit that vaporizes the juice so it can be inhaled). When it measures the resistance of dual coils it gives you the final output resistance in ohms just as it would if it were a single coil.
In the instance of dual coils, the resistance each single coil as compared to the final reading is almost half (almost in the case of RNA coils that may be .1 or .01 ohms from perfect) of the final reading. Why this happens I'm not entirely sure, I just know after building many dual coil RBA/RDA's that it is a fact.
In terms of the longevity of coils, as a coil gets used the coil will become thinner as the wire that forms the coil is fired repeatedly. The thinner wire will by nature hold a higher resistance over the same length of wire. So, what you should see is that the resistance of the coil will slowly increase as it is used over a number of months.
The VV mode is the easy way to do things and will actually make the calculation that the SVD does easier in terms of the way that it maintains a constant voltage as opposed to the way that it modifies the amount of power being pulled from the battery to hold a constant throughput into the coil at each time you fire it.
Anyway, long answer short, for a light flavor try 3.7-4.0v (I'll work out the wattage and get back to you) and for a heavier flavor (coffee or chocolate etc) try just a bit higher.
The sweet spot calculator is better if you are changing tanks/heads with various resistances and want to maintain the same hit on each tank and resistance.
Hope that helps
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