Frequent CMOS Battery Changes?

Megahertz · 18 Mar 2021

TV2 said:

The 5V from the power supply maintains enough juice to maintain the RTC and BIOS eprom.
If you turn the PS off, or disconnect the power from the supply to the wall then everything draws from the battery.
If there is a problem with the PS on that 5V then everything draws from the battery.
People who turn their PCs off but leave the PS on and plugged in will have their CR2032 last for years.
People who turn the PS off or disconnect the plug will have it last for months. 6 months is still a bit short.

When not in use I always turn off my computer and switch the surge arrest to off and my CR2032 is still good after 6 years. My wife does the same and her battery lasted for 10 years (and she only use her computer one hour a day).

Ghot · 18 Mar 2021

ignatzatsonic said:

Thanks for that Megahertz;

I wasn't aware of VBAT

I just checked my HWInfo64.

It shows VBAT at 3.104.

This is on a PC that is running 16 hours a day. The battery is the one supplied with the board. Nearly 5 years old.

27 or 28 thousand hours.

AIDA64 Extreme can do that also... here's an s/s of my OSD from AIDA64

Frequent CMOS Battery Changes?-image1.png

Steve C · 18 Mar 2021

Thanks to all for your help. I never thought such a simple query would create so much interest!

TV2 · 18 Mar 2021

Megahertz said:

When not in use I always turn off my computer and switch the surge arrest to off and my CR2032 is still good after 6 years. My wife does the same and her battery lasted for 10 years (and she only use her computer one hour a day).

You are probably right. I never do that so I wouldn't know.

Steve C · 19 Feb 2023

I still have to replace the CMOS battery on this PC every 6-12 months being powered on most of the time and turned off at the mains. I noticed HWInfo has a reading for 3VSB. What is that since the motherboard standby voltage is 5V?

Frequent CMOS Battery Changes?-capture.jpg

Berton · 19 Feb 2023

The most common CMOS battery in a socket on the motherboard is the 3Volt CR2032. I save them when junking computers as they tend to last quite awhile. The CMOS [Complementary Metal Oxide Semi-conducter] on the motherboard is where the BIOS is stored. The battery generally does not get recharged. Due to the small size of some Notebooks they may have encapsulated batteries with wire leads, some in a type of heat-shrink tubing and some may be 2 or 3 smaller linked batteries. The 3VSB item in the chart may be for System Battery.