CMOS battery location

[mjohnc1]

My hp laptop failed to bootup/start on return from  a weeks holiday. My pc was upgraded by me a year ago by fitting 1tb Kingston SSD  drive and 16mb RAM and has been working perfectly satisactorily until the failure to boot up -with  blank screen symptom  - together with 'computer on light' at rhs of machine coming on  for only 3 seconds at every attempted start up???.

I assumed either a motherboard failure or main battery failure as it was some 5 years old . I replaced the main battery with new but this had no effect . Simililarly despite being plugged into the mains I could get no pc response/screen from attempting F2 button access on any start up.

I then purchased the same working model of 15da 0511sa on ebay , replaced the installed  hard disc and RAM with my own upgraded units and found thereplacement pc to be in working order. ( perhaps with one exception , if I allow laptop to stop with new battery exhausted , on start uo I get a message that pc Bios needs to be rebooted ? is this what is referred to as PC boot looping???)) 

I am now wondering if I had a dead CMOS battery in my original laptop but I cant find the location of it at all despite removing hard drive, main battery, fan and even motherboard to inspect underside. Can anyone advise me where to find said CMOS battery on my hp15da 0511sa unit. ??? Internet searches seems to suggest some laptops are not actually fitted with CMOS batteries. , which begs the question how do they keep date and time correct.

Any inormation/comments gratefully received.

MikeC

[Paul_Tikkanen · Accepted solution]

Hi, Mike:

There is no RTC/CMOS battery in your notebook.

Most notebooks with internal batteries such as yours do not come with RTC/CMOS batteries.

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

If you look at chapters 3, 5 and 6 of the service manual, you will find no part number listed for a RTC/CMOS battery, or a removal and replacement procedure.

HP 15 Laptop PC Maintenance and Service Guide

[mjohnc1]

Txs for confirming my suspicions on absence of CMOS battery . 

Regards Mike

[Paul_Tikkanen]

You're very welcome, Mike.