I know that the pen style adapters can take the higher voltage, while I don't find that to be the case with the 901 style. As far as actual voltage goes with the prodigy, or any other device with rechargeable ion batteries, the voltage changes. I don't know what the prodigy starts at or finishes at. It is not at 5v the whole time though. I was just wondering what 3.7v batteries might start at compared to 3.0v batteries in the prodigy. I'm curious what effect the resistor would have. I have a vaping device that takes two 3.0v batteries and starts out at 6.8v with freshly charged batteries.