kernel_task fully saturates CPUs when MacBook pro not plugged in

I have been having issues when my MacBook Pro (16" 2019) is not plugged in or when I have an iPhone plugged into it.

If the machine is not plugged in, the kernel_tasks job fully saturates CPU usage and it will shutdown within a few minutes even though the battery monitor shows 95+% charge.

In addition, if I have my iPhone plugged into the laptop it will also randomly shutdown approximately 10-15 minute after the phone was connected (again, battery monitor shows near full charge on the laptop). This is true even if the laptop is plugged into a power source.

These problems screams of a power management issue... but I have no idea how to resolve this.

• I have started in safe mode. Same behavior.
• I have reset VRAM. Same behavior.
• I have created a new user. Same behavior.
• I have started new user in safe mode. Same behavior.

What else can I try? Is there something in the logs I should be looking at?

Thanks much,

mike