Originally Posted by sv650touring
According to the label on the battery, the maximum charge is 4.25v, so I reckon the PSP lowers the 5V that comes in from USB/charger.
Do you think Li-Po & Li-Ion similar enough that they could be run in parallel safely?
What if the Li-Ion was at a low state of charge and the Li-Po was fully charged? I would expect the claimed protection circuitry on the Li-Ion would prevent over charging. Are there any other concerns?
LiPoly batteries are easily abused and abused LiPoly batteries are prone to fail catastrophically (puff up and burn).
Since you don't know for certain if their are consequences in paralleling unlike battery types, I for one would not do that. Unless someone has documented proof that this can be done then my advice is don't.