Battery and CMOS

[skzoo08]

I'm having an issue with my laptop. The battery needs to be replaced. 2 weeks ago I checked the battery health and it said it was weak and now it's saying it needs to be replaced. I am using it plugged in because it says 0% when plugged in. Last night when put on my laptop I got a CMOS invalid message I never saw that before so was reading it and then the message came off and the laptop started coming on and the usual battery message came on I pressed enter and I used it as usual. I shut it down as I usually do after using it and I decided to put it on this morning to I plugged in and waited 10 min then put it on and I got the same CMOS as last night and the same thing happened and then the battery message came up and it came on nothing off except the time on the laptop was wrong so I changed it manually. 

I can't change the battery right now. So I would like to know if this CMOS thing is an issue now or can I continue using my laptop plugged in. Will my laptop not turn on one day cuz of this CMOS message? I'm just trying to understand what's going on and what I can do in the meantime until I can replace the battery.

[BeemerBiker · Accepted solution]

You should be able to ignore the CMOS message.   The laptop lost information but except for the date and time all the rest of the information is defaulted to the factory setup.   You should set the date and time correctly then use the "WIN + v" to clear the CMOS error.  If the date and time are not set correctly then windows (or linux) will not get updates.

Use the Windows key + 'v' as explained here.

DO NOT UPDATE THE BIOS IF YOU DO NOT HAVE A WORKING BATTERY.   You can probably get a battery for about $40 USD assuming it is available at your location.  I can probably find a disassembly video.

[skzoo08]

Thank you so much for helping. A battery costs $600TT or $88US in my country so I can't replace it until next month. That's why I wanted to know if the CMOS issue would cause problems that I needed to replace the battery urgently but since I can work around it for now it will give me time to get a new battery. Thanks again for helping me.

[BeemerBiker]

When you get the new battery installed please run the battery check to verify it is a genuine HP battery.

Note that it may not say "HP" for the battery vendor as HP gets batteries from several manufacturers.  The battery report will show if it was previous used and if it has the correct amperage. You can also compare you present battery to the new one.

You run the battery report by bringing up the administrator command window and running

powercfg/batteryreport

as shown below

After entering that explorer line you should see something like the following. You will have to click on it as it is long
https://stateson.net/docs/SP4_battery-report.html
Battery should last about 5 years but less for gaming systems.

Have you done a battery calibration?
If not, then do the battery report both before and after the calibration.
Save the results so you can compare.

Let me know what you find out.

[skzoo08]

I did a battery report 3 weeks ago because I usually charge my laptop twice for the day maybe 3 times for the most when using it. I realized that it was dying faster and I had to charge it more so that's why I did the battery report. It basically went from 3 hours to 1 hour to 30 min in the span of these weeks to literally being plugged in now with the battery staying on 0%. When I get the new battery I will keep you updated and also do the things you told me to do in the previous reply. 

[Hellen-Charless]

It sounds like you actually have two separate issues happening, but they may be connected.

1. Battery problem (main issue)

From what you described (battery health weak → now needs replacement → 0% even when plugged in), your battery is essentially fully degraded or not holding charge at all. In many laptops, when the battery completely fails, the system may behave oddly at startup because it briefly loses stable power during boot checks.

The good news is:

• You can continue using the laptop on AC power (plugged in) safely in most cases

• The laptop will still work normally without a battery as long as the charger is stable

Just avoid unplugging it unexpectedly.

2. CMOS message (important, but usually not serious)

The “CMOS invalid” or similar message usually means:

• The BIOS/CMOS settings were reset

• Most commonly caused by a failing CMOS/RTC battery (small internal battery)

That small battery keeps:

• Time and date

• BIOS settings

This explains why:

• Your time resets

• You saw CMOS warnings

• Settings don’t stay saved properly

Should you worry?

Not immediately.

You can still use your laptop, but:

• It may show the CMOS message again at startup

• You may need to reset the time each day

• In rare cases, BIOS settings may reset repeatedly

Will it stop turning on?

Very unlikely.

A CMOS battery issue does NOT prevent the laptop from turning on. It mainly affects settings and startup messages, not core power.

What you should do in the meantime

• Keep using it plugged in (that’s fine)

• Manually set the time when needed

• Avoid BIOS changes unless necessary

• Plan to replace:

  • Main battery (priority)

  • CMOS/RTC battery (if the issue continues)

Bottom line

You can safely continue using your laptop for now on charger power. The CMOS warning is annoying but not dangerous—it’s mainly a sign of a small internal battery issue, not a critical failure.

If you want, tell me your laptop model and I can explain exactly where the CMOS/RTC battery is and how expensive the fix usually is.

[skzoo08]

The CMOS message never came up before, it only came up when my battery remained at 0% which was last night. That was the first time I ever encountered that message.