Windows 10: Question about recent power outage and PC

Very well written educated reply, you know your stuff even though i only understand some thank you for your responses.

 

I am buying another and not trusting it again it was a Monster Surge Protector, thanks !
Did have my PC in storage for a few months about a year and a half ago, does my AIDA64 VBAT 3V show this as o.k. ?

 

Saying i should replace this battery ? Mention to OP i had it in storage for a few months about a year and a half ago, but had no issues since now. I do have one on hand CR2032.

 

At >3V your battery is fine. I only replace the coin battery when the BIOS complains about it. But for an accurate measurement you have to do it when the computer is unplugged and the coin battery is actually being used (since when the computer is on there is no load on the battery).

Intel allows it to drop to 2V:

 

So just take it out and test it with a volt meter ? Maybe better off changing it then anyway ? Since i have one.

 

No, measure it while the battery is still installed, if possible (it would depend on the type of battery socket on your motherboard). The battery voltage changes depending on the load that's connected to it.

But since it's >3V it's highly unlikely the voltage drop under load will be significant. I wouldn't worry about it. I have changed maybe 1 or 2 batteries in the past 30 years of owning PCs.

 

Volt meter is a superb diagnostic tool. If the battery is 2.8 volts, then plan to replace it in the next six months.

Another indication of a battery going bad long before it does go bad: clock will not keep accurate time when power is removed for a day or week.

 

My PC is switched off at the mains when not in use so I'm lucky to get more than 2 years use before the CMOS battery needs changing. I've had various problems with a CMOS battery just under 3V. I fail to see how a battery at 2V would work in the motherboards I've owned. If I'm fiddling with the PC and have the case cover off, I just replace any battery CMOS battery showing under 3V.

 

Yes, if you switch off the mains power most of the time then the battery is only expected to last ~3 years in the ideal case. 2V is Intel's requirement measured at the PCH. If the motherboard has other things connected to VccRTC and/or if the motherboard manufacturer used a cheap diode then there would be additional voltage losses between the battery and the PCH so the required voltage at the battery would be higher.

 

Power on or off make no difference to a CMOS battery life expectancy. The electrical concept is called shelf life. That CMOS battery lasts just as long in a computer as it does in the original package. Because power required by the CMOS and clock is so tiny. Much more 'life expectancy' is taken by self discharge that is taken by the CMOS.

Any battery that does not last more than five years implies a serious defect on that motherboard or inside the CMOS. And yes, we have seen some ICs that had an internal defect - caused its battery to discharge in days.

 

Do you have a spec for a typical CMOS battery drain?

 

My laptop has a built in rechargeable battery, and one day I could not get to bios at all. I had to (carefully) short circuit the battery - I used a light bulb in short circuit to avoid doing it to fast, and eventually it discharged and I got to bios. I really do not recommend this!

 

ICs that do this function typically consume 100 to 200 picoamps. Some will consume as much as 1 microamp.


BTW, never short a rechargeable battery in a laptop. That can cause explosions. CMOS battery in laptops is not the rechargeable battery. Laptops often have a separate coin cell to maintain clocks and CMOS settings. Better is to remove that battery and then wait for residual charges to dissipate.

 

Assuming your spec of a typical 200pA drain and a typical c. 200mAh CR2032 battery energy capacity then this gives a battery life c. 10^9 hours = 114,000 years! That's not my experience having used various motherboards from Asus, Gigabyte & MSI where I've been lucky to get more than 3 years life with the PC mainly off at the mains. A 1 microamp drain gives a life of c. 25 years which is still far short of my practical experience.

 

Intel rates the PCH drain at 6uA.