I swapped this in an fizzled eGo battery (1100mAh).

With no load, the voltages were 3.6v-3.9v-4.2v freshly charged.

There is, unlike the picture, an extra negative lead like the old eGo PCB. I probably should have used the existing leads mounted to the case and center pin because they used high temp solder which was a pain to remove.

After use, I think the 4.2v setting is whatever the battery can supply, it might also apply to the other voltages. It seems to be a fancy voltage regulator. It would probably work best with a higher voltage rated battery of high capacity to get the best out of it.