How to Know If You Need to Replace the Motherboard Battery (CMOS)
The signs (reset date, lost settings) and how to do it.
The CMOS battery (a small round battery on the motherboard) keeps the date, time, and BIOS settings even with the PC turned off and unplugged.
Signs it needs replacing
- The date and time reset to a default value every time you turn the machine fully off.
- BIOS settings (boot order, custom settings) repeatedly get lost.
- The machine takes longer than normal to find the correct time when reconnecting to the internet.
How to replace it
- Turn off and unplug the PC from the outlet.
- Locate the battery on the motherboard (round, silver, CR2032 type in most cases).
- Carefully remove it (there's usually a small latch or lever).
- Install a new CR2032, respecting polarity (the "+" side facing where the slot indicates).
This small change, besides fixing the date/time problem, usually also resolves other symptoms related to the BIOS "forgetting" saved settings between restarts.
Tip: it's a cheap, widely available component (any electronics shop or large supermarket has it) — don't hesitate to replace it if you suspect it's the cause, the cost is minimal.
Frequently asked questions
What type of battery do I need for the motherboard?
The vast majority of motherboards use a CR2032 battery, widely available at any electronics shop or large supermarket, at low cost.
Is it dangerous to replace the CMOS battery myself?
No, it's a simple and safe process with the machine turned off and unplugged — you just need to be careful with correct polarity when inserting the new battery.