Question When laptop battery is connected, CPU starts power throttling ?

[Deadeye5s]

(Moderator: thread moved to laptop tech support as more appropriate)

Whenever the battery is connected to my laptop and I try to play a game it severely power limits to 20-27 watts on the CPU specifically even though temps are fine (see pic). It flashes red PL1 on throttlestop limits
https://i.redd.it/dklnm8snbdve1.jpeg

If I unplug the battery cable however it is completely fine and runs without any throttling.

This happened after I opened the laptop to clean it, so maybe I damaged something then.

But it is very annoying as I have to unscrew the back panel, unplug and replug the battery whenever I need to take it somewhere.

Specs:
11th Gen Intel(R) Core(TM) i7-11850H @ 2.50GHz
NVIDIA GEFORCE RTX 3070 Mobile GPU (Max-Q Variant)
32GB DDR4 RAM @ 3200MT/S
Storage - Micron NVME MTFDKBA512TFH-1BC1AABHA
Windows 11 Pro Version 24H2
BIOS Version/Date HP T92 Ver. 01.17.01, 05/03/2024

 

[Lutfij]

This happened after I opened the laptop to clean it, so maybe I damaged something then.
If you think something was damaged, you might want to inspect the area around the battery and it's connector for signs of any visible damage. One other thing, did you replace the thermal paste and pads for the cooling assembly?

BIOS Version/Date HP T92 Ver. 01.17.01, 05/03/2024
I'm assuming you're on an HP laptop, correct? If so, please pass on the make and model of the laptop. Was the battery for the laptop replaced at any point?

 

[Misgar]

If I unplug the battery cable however it is completely fine and runs without any throttling.

When you say "battery", do you mean the AC mains power supply, or do you mean the Lithium battery inside the laptop? If you unplug the battery from the motherboard, e.g. when replacing the battery, you sometimes have to press a battery reset switch (on Acer laptops) when you replace the cover.

I've seen this "low power" problem on a Lenovo laptop. When I plugged the owner's power supply into the laptop, the CPU ran at 800MHz. When I unplugged the mains PSU, the CPU ran at full speed from battery. Bizarre!

I traced the problem to a faulty PSU. It was outputting the correct voltage (19.5V) but a "sensing" resistor in the yellow DC plug had gone open circuit. When I changed to another identical Lenovo PSU, the problem disappeared.

My old HP laptop has a blue DC plug and it too may have a "sensing" resistor or some other circuit which the laptop uses to confirm you've connected a valid PSU (I don't know this for a fact, I'm just guessing). If you have another PSU, see if it restores normal operation.

 

[Deadeye5s]

This happened after I opened the laptop to clean it, so maybe I damaged something then.
If you think something was damaged, you might want to inspect the area around the battery and it's connector for signs of any visible damage. One other thing, did you replace the thermal paste and pads for the cooling assembly?

BIOS Version/Date HP T92 Ver. 01.17.01, 05/03/2024
I'm assuming you're on an HP laptop, correct? If so, please pass on the make and model of the laptop. Was the battery for the laptop replaced at any point?

I inspected the area and didn't find anything unusual but I am also unsure what to look out for. When I was cleaning I just cleared the dust so I didn't take the heatsink off anyways.

The laptop battery was not replaced, though it is still under warranty. My laptop is the HP Zbook Studio G8.

@Misgar When I say battery I am talking about the lithium ion battery. I think I have already reset it before (I believe on my laptop it is done by disconnecting the battery and holding down the power button for 30 seconds)

I don't think it is an issue with the power supply as my laptop runs perfectly when the lithium ion battery is disconnected so surely the problem is linked to that.

 

[Misgar]

(I believe on my laptop it is done by disconnecting the battery and holding down the power button for 30 seconds)

If I'm understanding this web site correctly, pressing the power button for 30 seconds after unplugging the battery just drains any remaining charge from the capacitors and clears anything remaining in memory.
https://smallbusiness.chron.com/reset-hp-laptop-holding-down-power-button-battery-out-56662.html

"Remove the battery, then flip the computer right-side up and open the lid so you have access to the Power button. Press and hold the button for about 15 seconds. This drains the capacitors on the computer's main board that act as a kind of backup to your battery. Once they're drained, anything in your memory is flushed away and your system will be able to do a clean boot."

I don't think this constitutes "resetting" the battery. Rather, I believe it's intended to clear any data remaining in RAM and additionally (if you remove the BIOS battery) it wipes all the BIOS settings too. I may be wrong though.

Pressing the power button is not the same as the battery reset micro switch on some Acer laptops. This is accessed through a pin hole on the base of the laptop and needs to be pressed if you disconnect and reconnect the battery for any reason.

View: https://youtu.be/KNFH8f75a6s


My Acer has a second micro switch on the motherboard which stops the laptop booting up when the bottom cover is removed. If you don't replace the bottom cover, the laptop will not start up.

Please note I'm not suggesting your HP laptop has a similar battery reset switch, but if it's anything like my old Acer Aspire, you need to inform the BIOS you've just reconnected a battery, even if you haven't actually replaced it.

Perhaps the HP forums can provide a better answer.