Skip to main content

Business class notebook and mobile workstation released by HP in August of 2008. The laptop this guide is based off of is identified by the S/N CNU20937TQ.

9 Questions View all

Computer doesn't turn on

My laptop was sitting in a shed for like half a year. That's when I think the CMOS died. Any ideas on how I can replace the cmos? I am quite certain of this because it turned on earlier, and said the cmos clock is invalid.

Answer this question I have this problem too

Is this a good question?

Score 0
Add a comment

1 Answer

Most Helpful Answer

Okay, a little clarification is in order here. First of all, CMOS refers to the memory storage technology that holds certain pieces of configurable memory. CMOS RAM takes very little power to maintain storage, so it is normally backed up with a coin cell battery.

When that battery dies, the memory it holds gets lost. That information can contain things like BIOS settings and the date and time information, which is why that battery is often also referred to as the RTC, or Real Time Clock battery. Note that nothing prevents you from using the computer even with a dead battery, but you may have to set the date and time and any necessary BIOS settings every time you turn off the computer.

The instructions you need to replace that coin cell battery are in the Maintenance and Service Guide under your computer's device page. Go to Page 83 and read through the section titled RTC Battery; it has all the information you need to replace that battery. The HP part number is 651948-001; looking up that part it's a coin cell that comes with two wires and a plug pre-connected so you just have to plug it in. Here's an example I found; there are several more, but most of them are charging in the neighborhood of $30 for the darn thing.

Replacement RTC CMOS Battery for HP (Part Number) 651948–001 - Walmart.com

Once you've got the new battery in place, you'll have to go through and set the date and time and any other BIOS settings you need, but the new battery should maintain those settings for the next couple of years at least.

Was this answer helpful?

Score 1

2 Comments:

I have a cr2032 battery.. I presume that should work. And other thing, my laptop's sn is cnu2023P7Z

by

As to whether the 2032 battery will work, yes and no. Yes in the sense that all button cell batteries have the same voltage and so it will correctly power the CMOS memory.

The problem is, the replacement battery comes with wires already soldered/spot welded to the battery so you're going to have to do that to your button cell. I'd advise caution, though, because heat is the enemy of battery chemistry. If you solder the wires directly onto either side of the battery itself, you stand a very good chance of ruining it and rendering it unusable. That's why most batteries use spot welded strips of metal, since the spot welding subjects the battery to a much shorter duration of heat than soldering will.

So yeah, if you have a spot welder for batteries, go for it, but I'd consider very carefully whether to take a chance on soldering the battery vs. just paying the $10 USD or so to buy one already set up for you.

BTW, the serial number doesn't matter; they're all different. It's the model number that's of interest.

by

Add a comment

Add your answer

maharshi878 will be eternally grateful.
View Statistics:

Past 24 Hours: 0

Past 7 Days: 1

Past 30 Days: 7

All Time: 26