Requirements for power adapter

[Steve Simpkin]

The original USB adapter/charger that came with the HP Prime was rated at 5 Volts, 1 Amp. As noted by others, any 5V USB adapter, including the one you have, should work fine. I would recommend using a well know brand for safety reasons.
https://www.hpmuseum.org/forum/thread-17...54159.html

I would not be concerned about the battery voltage. A 3.7v lithium battery has a nominal voltage of 3.7 V and a full-charge voltage of 4.2 V is not unusual.