CMOS checksum erro after replacing main battery

[DMendes]

Hello,

thank you very much in advance for reading the post and for your support.

My HP laptop 14-CK0599SA battery started to lose its capacity and eventually started getting an error (Primary internal Battery: 601) when starting the laptop:

Bios has detected that the capacity of the internal battery has been reduced.

I ordered a new battery HP part number L11421-421

After installing the new battery I started getting another error upon starting the laptop:

The CMOS checksum is invalid. CMOS Reset (502)

By pressing enter the PC starts. Initially, the date and time displayed relate to that of the previous time it was switched on which automatically updates after a couple of minutes. 

While the laptop is turned on the new battery functions well, and it has good capacity. If turning off the PC and staying off for maybe more than 10 minutes I can only start it again by connecting the charging cable and I get the checksum error again. This is quite annoying.

When switching back to the old battery I again get the old battery capacity error message but not the CMOS checksum error.

I searched that the checksum error may be related to the CMOS  battery being bad but it seems that this laptop does not have one and it would not explain the problem going away when reinstalling the old main battery. I also checked that my BIOS software is up to date.

I then noted that the old and new battery specs are slightly different but both are HP products and the website listed compatibility with my laptop model. Could this be the problem?

Old: 11.55V and 3470mAh

New: 11.4V and 3420mAh

Thank you

Duarte

[Nal_NR]

Hi @DMendes,

Welcome to the HP Support Community. 

I understand that you are getting CMOS Reset (502) error. I'd like to help!

Please follow these steps once and if it fails keep me posted. 

CMOS Reset (502) The CMOS checksum is invalid

During the startup process, the system performs a checksum test of the BIOS. If the checksum is incorrect, the BIOS is assumed to be corrupt and the system installs a hidden copy of the BIOS to correct the problem, and the startup process continues. The following message displays for 15 seconds before the computer automatically reboots. You have the option of pressing enter to proceed without waiting 15 seconds.

To resolve the CMOS Reset Error (502), restore the BIOS.

Press enter to restart the PC.

If the error displays after restarting, try to restore the BIOS using a USB drive. For more information, see the "Recover the BIOS using a USB recovery drive" section of the following:

For desktop computers, go to HP Desktop PCs - Recovering the BIOS (Basic Input Output System).

For notebook computers, go to HP Notebook PCs - Recovering the BIOS (Basic Input Output System).

If restoring the BIOS fails, contact HP.

Hope this helps! 

Please click “Accepted Solution” if you feel my post solved your issue, it will help others find the solution. Click the “Kudos/Thumbs Up" on the bottom right to say “Thanks” for helping!

[Nal_NR]

Hi @DMendes,

Hope I was able to fix the issue. If you need further assistance, feel free to reach out to us. 

Give us some reinforcement by clicking the Accepted Solution button, that'll help us and others see that we've got the answers and did reply to you!