Powering 150 W HP ZBook Power 15 G9 from 100 W HP Z40c via USB-C.

[JiriTlusty]

Can I power 150 W notebook HP ZBook Power 15 G9 from 100 W display HP Z40c via USB?

I know that it is 150 W notebook on the 100 W source but notebook will consume less than 100 W most time. So, the question is:

Will be this power source completely rejected? Or, will be notebook partially powered up to the 100 W limit?

[TzortzisG]

Partially powered. Definitely. The G9s should have the "boost converter" option in their BIOS, same as G8s, which will take care of any overwhelming power demands if enabled. Charging battery however while working on computer will overtax powersupply.

[JiriTlusty]

Ok, sounds good.  But I do not completely understand your remark on overtaxing powersupply when charging battery. Can I charge it on USB? Please, do you know what happens,

1.  if I am on USB power, working on the computer without fully charged battery? Will be the battery up to the available power source slowly charged, or it is only my dream?

2.  when due to some hard computation, power needs of the computer exceeds 100 W. Is on USB power e.g. CPU/GPU throttled or somehow limited/powersaved to limit its power to 100W?

If there is some documentation regarding this issues, I will be grateful for the link.

Thanks a lot.

[TzortzisG · Accepted solution]

You can definitely charge it fully when switched off. But frankly I cannot tell you how and if it will be charged if you're (for example) playing a game with an empty battery, thus fully using CPU+GPU. It might still trickle charge, or it might not charge at all (most probable).

-  2.  when due to some hard computation, power needs of the computer exceeds 100 W. Is on USB power e.g. CPU/GPU throttled or somehow limited/powersaved to limit its power to 100W?

If boost converter is enabled in BIOS (as stated in my previous post) then laptop will get the necessary additional power from battery, thus drawing current (discharging) battery for a little while, even though plugged in:

http://h10032.www1.hp.com/ctg/Manual/c06696065.pdf page 48

 "Boost Converter Setting When checked, the notebook draws power from the battery when the system is on AC to give the CPU a momentary performance gain by increasing the overall power available to the CPU."

If boost converter is OFF, cpu and/or gpu will see POWER THROTTLING limits being applied....

- 1.  if I am on USB power, working on the computer without fully charged battery? Will be the battery up to the available power source slowly charged, or it is only my dream?

If moderately used (browsing, office work, etc.) it SHOULD see a (slower than usual) charging. 100W is not negligible...

To be honest no exact documentation for your specific questions/case. Only by trying it can you be 200% sure.