I'm currently vaping a Prodigy at 3.7
with the resistor switch. I do plan to get the switch without the resistor when they get more in.
I was murdering atomizers at 5 volts and decided to switch to 3.7 volts for economic reasons. During the time I ordered the replacement batteries and when they came, Casey (very patiently) helped me with some troubleshooting and we found that the switch was slightly out of place, pushing the solder joint against the barrel and producing the intermittent short that was driving me nuts. Some gentle persuasion corrected that.
So I got the 16850s (robin's egg blue) in and haven't run it on the RCR123As since.
Vapor quantity is slightly better than with a standard 801 battery, and the vapor is much more consistent. In other words, the vapor is about half what the Prodigy does at 5 volts.
Flavor is better at 3.7 volts. Some subtle flavors (maple and some cherry flavors) were masked at 5 volts. I'm getting 4.18 volts at the adapter now even
through the resistor. (And I've seen 7.10 volts at the adapter from freshly charged RCR123As.) Of course, these are at no load, but I usually see around 3.78 volts from a freshly charged standard 801 battery.
I'm curious to see what the non-resistor switch will be like on the Prodigy at 3.7 volts. I'm also going to get some spare switches as these appear to be THE most likely failure point on the device.
The batteries are marked "2600 mAH Li-ion 18650 3.7V." I ordered them from all-battery.com and the part numbers were
39129 for the batteries (four) and
01210 for the charger. This actually turned out to be a travel charger. The prongs fold down when not in use. Unless you need a travel charger, there's another charger they sell that charges BOTH RCR123A and 18650 batteries.