Originally Posted by ggcrandall1
LiPo cells have a full charge voltage of 4.2 volts. LiIon cells are fully charged at 4.1 volts.
Lithium ion cells generally available these days are said to be fully charged at 4.2V just as lithium polymer cells. For all intents and purposes they look and act the same, except they generally do not tolerate high rates of charge (or discharge, not an issue here) that lipo cells/packs can.
For the OP, is 5 volts actually present at the internal cell or is there additional circuitry inside the PSP bringing it to some regulated max voltage at 4.2 or less?