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marethyu · 11-19-2024, 07:30 AM

Hi,

I am not sure about the requirements for a power adapter for charging HP Prime G1. I lost the prepackaged official power adapter a long time ago. I am bit concerned with the power adapter I have been using so far. It seems like Li-ion battery HP prime uses requires an adapter that supplies the output of DC 3.7 V/1.5 A, right? My current power adapter output is DC 4.75-5.25 V / 1 A. I wonder if it is problematic that I should get a new adapter.

Also, when I measure the voltage of the Li-ion battery using my multimeter, I noticed it supplies around 4.18 V, not 3.7 V. Should I be concerned?

Steve Simpkin · 11-19-2024, 01:01 PM

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.

RPNerd · 11-19-2024, 01:23 PM

(11-19-2024 07:30 AM)marethyu Wrote: It seems like Li-ion battery HP prime uses requires an adapter that supplies the output of DC 3.7 V/1.5 A, right?

Wrong, I'm afraid. It is indeed a 3.7V battery but it's also a microUSB port on the calculator, and that has to conform to a number of standards, including the one that says that the power lines on a USB port provide 5V unless something different has been negotiated between the charger and the device being charged. That's why you don't damage the calculator when you connect it to a USB port on your computer.

(11-19-2024 07:30 AM)marethyu Wrote: My current power adapter output is DC 4.75-5.25 V / 1 A. I wonder if it is problematic that I should get a new adapter.

Not a problem at all. That'll work fine.

(11-19-2024 07:30 AM)marethyu Wrote: Also, when I measure the voltage of the Li-ion battery using my multimeter, I noticed it supplies around 4.18 V, not 3.7 V. Should I be concerned?

No, that's normal for a Li-ion battery that's not actually powering anything. Once it's in circuit and under load and once it is no longer fully charged, you'll get the nominal voltage of 3.7V. While it's being charged, that will go up to around 4.4V.