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- HP Community
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- Notebook Hardware and Upgrade Questions
- ZBook Power G9 DC power specification

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07-14-2025 08:01 AM
Hi,
first of all where to find the documentation? The Quickspecs I have for the G9. But for the G8 I also have a "User guide" with a chapter Input power and the DC power specifications for charging via USB-C (is it PD Power Delivery?)
For instance for the G8 there is:
19.5 V dc @ 2.31 A – 45 W
19.5 V dc @ 3.33 A – 65 W
etc.
Is it the same for the G9? In the past I was never able to charge a G8 with PD chargers below 100W. Actually 45W or 65W should already be able to charge it, even if not at highest rate...
What about the G9?
07-14-2025 09:48 AM
Hi @msssm
in order to charge you must have a 150 Watt USB-C charger, the same power as the normal AC charger, otherwise you can only charge when the laptop is turned off.
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07-14-2025 09:48 AM
Hello msssm.
The HP Support page for you system has the maintenance manual which on page 150 mentions:
19.5 V dc @ 6.15 A – 120 W
19.5 V dc @ 7.70 A – 150 W
Both the manual and the QuickSpecs you've already seen list 120W and 150W chargers as the ones offered originally with this series. No mention of USB-C chargers, and this -according to HP- means you're on your own if you want to power this system from a USB port. This workstation needs a lot of juice and therefore 100W more than likely will not be sufficient. You still might be able to charge it when completely turned off.....
07-14-2025 12:52 PM
Okay this is not true. I have a 100W PD USB-C charger that able to charge while running, eventhough Windows is complaining about a low power charger. But it is charging.
The charger even works when powering an usb-c Dock which itself charges the ZBook.
This works for G8 and G9.
Now only the G8 docs mentions the supported USB-C PD Standards.
As you confirmed the G9 docs only mention the 2 available HP power supplies, and nothing about USB-C.
Anyway, G8 and G9 Specs are quite similar.
Now what I like to know if a USB-C kKVM switch supporting 60W (20V/3A) charging power would be able to drive this Zbooks.
From G8 specs it should work. There is nothing mentioning that these specs are only true while not running:
07-15-2025 07:17 AM - edited 07-15-2025 07:28 AM
Yes. Thank you for informing us that the G8 and G9s you own can be powered successfully with the 100W charger you have. Official HP policy on this matter, handed down by HP personnel is pretty much something along the lines of "If the manual or other HP docs don't mention an HP USB-C charger sold for this model, we don't guarantee that any USB charger will perform as it should." This is why I said "more than likely".
However, I had a similar discussion about this almost three years ago with another owner of this workstation, and it did seem that 100W was actually OK: https://h30434.www3.hp.com/t5/Business-Notebooks/Powering-150-W-HP-ZBook-Power-15-G9-from-100-W-HP-Z...
Anyways, I stand corrected. 100W will work for this 150W system. This 2023 post seems to indicate that 60W is not enough: https://h30434.www3.hp.com/t5/Notebook-Hardware-and-Upgrade-Questions/ZBook-Power-G9-won-t-charge-wi.... Again, the answer is "more than likely" won't work.
07-15-2025 09:03 AM
Probably charges you with 100w because you don't have a second disk installed. The power supply error message is just to indicate that there is not enough power.
Now the USB-C ports on these devices are Thunderbolt, this means that you need 5V/3A, a normal USB-C port needs 5V/1.5A so you need your charger to be 5V/3A minimum otherwise it will not charge on.
Some Thunderbolt devices may have the ability to switch to non-Thunderbolt mode for less than 1.5A current. In non-Thunderbolt mode, the computer continues to detect devices without Thunderbolt capabilities.
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