HP Probook 450 G7 CMOS or Battery issue?

[Bob10410]

I have a HP Probook 450 G7

I have these errors: 

POST Error

The system time is invalid. This may be a result of a loss in battery power.
Set the correct time and date using your operating system. If this message persists, you may need to replace the onboard battery.

Real-Time Clock Power Loss (005)

ENTER – Reboot the System

POST Error

HP Battery Alert

BIOS has detected that the capacity of the internal battery has been reduced.
This may be caused by environmental factors such as low ambient operating temperature, or it could be due to aging of the battery pack.
Operating your system in a warmer location or operating your unit for a while might resolve this condition.
If the condition persists or if you have an older system, please contact HP service.

Primary (Internal) Battery (601)

Enter – Continue Startup

Now my laptop only starts when it is plugged in. Do I need to replace the CMOS battery or internal battery?

Thanks

[Paul_Tikkanen]

You probably need to replace both batteries.

The CMOS battery maintains the BIOS and system clock settings and the Primary (Internal) Battery (601), and notebook not booting up unless it is plugged in seems to indicate the main internal battery is bad.

Below is the link to the service manual.

Maintenance and Service Guide HP ProBook 450 G7 Notebook PC

Chapter 3 has the RTC and main battery part numbers.