Your meeter probably isn't set up to properly measure RMS voltages from pulsed DC waveforms (most aren't - unless they specifically say they are) - the readings you get may vary from others because of the meter you are using and how it reacts to pulsed signals- more important than how much it's off by is that you get consistent readings when its fully charged and discharged.
Also, when your batterys are worn, you will see shorter run times- but fully charged/right off the charger they should not produce different voltages unless there is something wrong with your PCB's.
Perhaps you are right. I'm using a Fluke 11 multimeter set to DC voltage. But, on other had, I do get very clear differences when reading say the unloaded voltage of a Riva, 750 mah bat versus the unloaded voltage of a Joye, 650 mah bat. Riva, 750 mah bat probes out at 4.2v, unloaded, just off charger. Charger is labeled as "Output DC 4.2V 420mA". That suggest to me that 4.2v, unloaded, just off charger is correct. (Perhaps an interesting point here is that instructions that come with Riva bat say to initially charge it for 8 full hours whether charge light is green or not. To be it seems to be suggesting that charging continues if if green. But, bat university says li-ion should not be over charged. Per 4.2v output limits overcharge potential?) Then on Joye, 650 mah, unloaded, just off charger I read 3.44v. Presumably that is meter's interpretation of the PWM output of bat through its board. By memory that seems to jive with other posts on this thread although probably not a post of Scottbee as, my memory, he had little faith in unloaded voltages. But what I have found - 4.2v for Rives just off bat and 3.44 (let's call it 3.4v) for Joye. Both numbers - unloaded. Then same reads but loaded at 2.5 ohms - Riva, 3.81v and Joye, 3.23v. Use both for several hours then 2.5 ohm loaded voltage becomes ~3.37v for Riva and 3.23v for Joye. The Joye (regulated) tends to stay close to a constant number throughout charge life. But on Riva loaded voltage declines for the 3.81 just off charger, to 3.37v after several hours of use, to finally about 3.05v just prior to cut-off. That is, not much change for Joye but considerable time decline for Riva. But Riva only gets to Joye range for short time period just prior to cut-off. For most of use within any charge cycle, Riva is higher than Joye. Perhaps there is meter person out there who could from numbers given determine the peak voltage of a pulse of the regulated bat presuming that pulses occurred in regular cycles. I think Scottbee showed "regular" cycle was present in the later period Riva SE. But - returning to basic point - I think the Rivas (and not just the SE Rivas) are unregulated and I think for majority of a charge life those Rivas produce more watts than Joye's or Tornado regulated bats. To me, noticeable (notwithstanding volts or watts) in terms of amount of vape and, for juices I use, noticeable in terms of improved flavor. Also, I don't think there is any real difference in mah of Joye or Riva. Different numbers come from different methods used to calculate the numbers. The watt-hours of the basic li-ion bat used is same for both Riva and Joye. Bottom line, basically better vape with Riva - IMO.
