problem with starting laptop after battery replacement "Check sum invalid"

[mr_ok]

Hello, i have similar problem like here

https://h30434.www3.hp.com/t5/Notebook-Operating-System-and-Recovery/Cmos-check-sum-invalid/td-p/667...

So basically after replacing the battery that didnt work correctly (didnt charge up to 100% but only 80%-85% and randomly abbruptly discharged to 0% from 30%-15%) when PC is hibernated or switch off for a while without being pluged in, it cannot be switched on. I must plug it in before, and switch it on again. then it starts. But the black screen (BIOS) monit apears saying the CMOS CHECKSUM IS INVALID, AND IT WILL BE RESET. And then the sysetem loads or wake up normally.

(Additionally i extended RAM by another 8GB - i dont know if that is connected - normally the additional RAM is seen normally resulting in 16GB avaliable).

[pbroussard]

Have you calibrated the battery yet? A new battery requires calibration. 

https://support.hp.com/us-en/document/ish_2268927-1713329-16 

[mr_ok]

Thanks for the advice. So I tried that (but i skiped 6hrs waiting after battery is flat, before charging but i hope it's not a big issue). But the problem of the check sum error keeps appearing on a startup. 

But as far as i understand the callibration the new battery has charged to 100% and also gone down to around 0% when switched off. 

I read a bit of that too, and some mentioned bad bios batterie. But wouldn't it be too big coincidence that it went bad just when the battery was replaced?

[mr_ok]

Ok, it seems that occured yet only once, just after calibration. From then it is ok so far.

[mr_ok]

It seems that it helped only for a week. today the problem has came. Battery full, laptop not starting after power pressed.

After plug in and power, first: pretends to start (some noice: fan or CD-ROM drive, then nothing), next: check sum error, reboot/restart and then it turns on.

I dont know maybe i should in fact wait these 6hrs with battery flat?

PS: it looks a bit like the problem is only when the battery is full. When it is partially discharged it starts with no problem.