Battery codes indicate the size of the batteries (i.e., 16340 is 16mm diameter and 34mm long and the 0 denotes cylindrical cell. Standard 16340s are about the same mAh wise as the Riva--750 mAh.
The power (heat) your PV generates is calculated using the Ohms Law:
Wattage (power) = Voltage/Resistance x Voltage.
For example, 3.4v battery and a 3.5Ω carto will generate 3.0 Watts [3.4/3.5 x 3.4 = 3.0]
This little calculator comes handy. Don't leave home without it (and without your trusty multimeter).
Online Conversion - Ohm's Law Calculator
Ah, battery codes = battery size. Great.
Now, that leaves one question: are SmokeStick cartos 3.5 ohm, or was that just the example?