CMOS Checksum is invalid

[OmChakane]

Every time I switch on my laptop (HP Pavillion 15), it gives me this message:

"The CMOS checksum is invalid. The CMOS will be reset to the default configuration and will be rebooted. Please check your BIOS setup options to see if they change.

CMS Reset (502)"

I opened my laptop and checked for the CMOS battery. Apparently, HP Pavillion doesn't have any CMOS. It has one single li-ion battery. Moreover, I observed that one side of the batter was puffed up a bit.

WHAT DO I DO? Should I order a battery online and replace the old one? Or is there any software upgrade that needs to be done?

[Paul_Tikkanen · Accepted solution]

The main battery also serves as the CMOS battery which maintains the system BIOS and clock settings.

You will have to replace the battery and you should just because it is beginning to swell and eventually will swell to the extent of causing stress to the notebook's internals and the case.

Battery swelling can be caused by leaving the notebook connected to A/C power and leaving the battery in a constant 100% charge state.

See this link for how to get the most life out of your notebook's battery.

HP Notebook PCs - Improving battery performance (Windows) | HP® Support

Below is the link to the parts list for your notebook:

HP PartSurfer

The battery part number and description is:

L11119-855

Assembly-battery 3C 41W 3.6A LI HT030

If you live in the United States (your notebook's model # is not sold in the United States), you can order a new HP battery from the link below:  $100.40

The HP Parts Store - HP Computer Parts - HP Printer Parts - HP parts - hp batteries - SSD - printhea...

If you do not live in the United States, you will have to buy a compatible aftermarket battery from another reseller that references the L11119-855 battery part number.

Below is the link to the service manual:

Maintenance and Service Guide HP Pavilion 15 Laptop PC

[OmChakane]

I removed the battery and checked running while plugging in the charging. I still got the error of cmos.

[Paul_Tikkanen]

Naturally.

Anytime you turn off or restart the PC, it will generate the error because there is no electricity (even for half a second) to keep the CMOS settings.

I've given you all the help I can with this problem.

[OmChakane]

No worries. Thank you so much for the help 🙂

[Paul_Tikkanen]

You're very welcome.