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Can a CMOS battery die in a few months?

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Hi, i have a little issue, and i assume it's the CMOS battery. It happens randomly. But whenever i shut the PC down and plug it off the wall (because here in Argentina we have horrible electriciy companies and for safety i plug off the PC from the wall) the CMOS battery resets the BIOS to its defaults, time get stuck at the time i shut the PC down for the last time, but it keeps the profiles i saved. I remove the battery and i saw some dust in it, but just now i replaced with another one. The question is: Can the CMOS battery die or fail in 9 months, or can it be that it was a little bit dirty in the underside? I have a Maximus Hero XI WiFi with an i5-9600k. Thanks in advance!
 
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Not normally, no.

To see if it's the battery causing the problem, measure the voltage of the battery with a voltmeter.

They won't hold anymore at ~2.0V, so if the battery measures this or below, it's bad.

I've pulled them from motherboards 10 years later, and they were still over 3V. (~3.3 is new, 3.7 is li ion chemistry, sorry.)

Those batteries only supply a few microamps of current; they don't really wear out, as much as age out after 5 to 10 years, when the battery material finally dies.

I've never personally had one die within ~10 years.

If there's a capacitor on that circuit, it may be shorting, and causing a problem, or dirt might cause a short, but it really should last 10 years.

If you think it's the motherboard, measure the current draw the motherboard is drawing from the battery with an ammeter. (a hand multimeter will not measure that current, so if it shows a current draw at all, something's bad.) It should be below ~5 microamps.

EDIT: I see you're unplugging from the wall; Modern computers use a bunch of standby current, up to 3A is the spec these days.
With everything having a settable operating point, like video cards and such, maybe it draws more current. IDK.

If your power is terrible, we used to use a SOLA transformer to clean up the power; they're pretty expensive, and run hot, so it may not be an option.



EDIT2:
Intel has something pertinent. This is old, too; modern boards may use even more power.


A coin-cell battery (CR2032) powers the real-time clock and CMOS memory. When the computer is not plugged into a wall socket, the battery has an estimated life of three years. When the computer is plugged in, the standby current from the power supply extends the life of the battery. The clock is accurate to plus or minus 13 minutes/year at 25 degrees C with 3.3 VSB applied.
SO, yeah, it could possibly be a wear item.
If you change it with the power on, it should keep the settings, though.
 
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Not normally, no.

To see if it's the battery causing the problem, measure the voltage of the battery with a voltmeter.

They won't hold anymore at ~2.0V, so if the battery measures this or below, it's bad.

I've pulled them from motherboards 10 years later, and they were still over 3V. (~3.7 is new)

Those batteries only supply a few microamps of current; they don't really wear out, as much as age out after 5 to 10 years, when the battery material finally dies.

I've never personally had one die within ~10 years.

If there's a capacitor on that circuit, it may be shorting, and causing a problem, or dirt might cause a short, but it really should last 10 years.

If you think it's the motherboard, measure the current draw the motherboard is drawing from the battery with an ammeter. (a hand multimeter will not measure that current, so if it shows a current draw at all, something's bad.) It should be below ~5 microamps.

EDIT: I see you're unplugging from the wall; Modern computers use a bunch of standby current, up to 3A is the spec these days.
With everything having a settable operating point, like video cards and such, maybe it draws more current. IDK.

If your power is terrible, we used to use a SOLA transformer to clean up the power; they're pretty expensive, and run hot, so it may not be an option.

I have low tension, i don't know the real translation, and a tension elevator (i don't know the real trasnlation either) to keep the electricity watts normalized. Now i remember i use to had a problem with a Z97 gigabyte motherboard, similar to this, and it was dirt in the battery. Thanks for your info btw.
 
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Tension translates to Voltage, I think, so if you have a tapped transformer, with the voltage raised, it makes the variations in voltage bigger.

I've seen that problem; it can make an old style TV go pow! :)

Modern TV's have power supplies like computers, so not so much anymore.

Make sure the power supplies you buy are 110-240V rated, and it will minimize problems too.
 
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Tension translates to Voltage, I think, so if you have a tapped transformer, with the voltage raised, it makes the variations in voltage bigger.

I've seen that problem; it can make an old style TV go pow! :)

Modern TV's have power supplies like computers, so not so much anymore.

Make sure the power supplies you buy are 110-240V rated, and it will minimize problems too.
I have an UPS too. Here's is 220v and now i have 216v. The thing is when i had a GTX 1070 i didn't have the problem. The problem started when i bought a 2070. Can it be applying pressure to the CMOS battery. It just under the card or is it just coincidence?
 

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I have an UPS too. Here's is 220v and now i have 216v. The thing is when i had a GTX 1070 i didn't have the problem. The problem started when i bought a 2070. Can it be applying pressure to the CMOS battery. It just under the card or is it just coincidence?
The battery isn't rechargeable, so it's just going to slowly drain over time. If you are asking it to power the CMOS for several hours every single day, I can definitely see it dying in less than a year. I've put computers in storage for just a couple months, and come back to them with dead CMOS batteries.

And if you get a decent power supply with active PFC, you shouldn't need to unplug your computer, especially if you have an UPS.
 
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The battery isn't rechargeable, so it's just going to slowly drain over time. If you are asking it to power the CMOS for several hours every single day, I can definitely see it dying in less than a year. I've put computers in storage for just a couple months, and come back to them with dead CMOS batteries.

And if you get a decent power supply with active PFC, you shouldn't need to unplug your computer, especially if you have an UPS.
Thanks for your answer. I have a BitFenix Whisper M 750w.
 

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Thanks for your answer. I have a BitFenix Whisper M 750w.
You should be fine to leave it plugged in. It will handle anything from 100 to 240v. Plus, if you have it plugged into a UPS, the UPS should protect the computer.
 
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You should be fine to leave it plugged in. It will handle anything from 100 to 240v. Plus, if you have it plugged into a UPS, the UPS should protect the computer.
Thanks for your time! I'll do that.
 
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The video card probably draws some power to save settings as well, so it could be the source of the problem.

Leaving it plugged in should fix the issue; that way it draws off the VSB from the power supply. :)
 
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The video card probably draws some power to save settings as well, so it could be the source of the problem.

Leaving it plugged in should fix the issue; that way it draws off the VSB from the power supply. :)
Thanks! One question: When the CMOS resets it reset everything on BIOS except for the profiles i saved. The time stucks at the hour i shut down and unplug the PC. Shouldn't the time be 00.00hs? Or am i wrong?
 
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The overclocking profiles on my mobo are saved in flash ram, apparently, because you have to overwrite them to change them; clearing CMOS won't lose them.

I think that's on purpose, so you wont have to reset everything if you have to recover from a bad OC. :)
I've had to clear cmos to get it to boot before, lol.
Like the time it tried to boot at 5.1GHz, lol.
 
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The overclocking profiles on my mobo are saved in flash ram, apparently, because you have to overwrite them to change them; clearing CMOS won't lose them.

I think that's on purpose, so you wont have to reset everything if you have to recover from a bad OC. :)
I've had to clear cmos to get it to boot before, lol.
Like the time it tried to boot at 5.1GHz, lol.
Well, thanks. I'll try keeping the PC plugged in and see what happens with the new CMOS battery. Have a nice day!
 
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If your battery is a 2016, you might see if you can get a 2020 or 2032 to fit in the holder; the difference is the thickness.

20xx is 20mm dia, and the xx16 is 1.6mm thick.

Typically, a 2032 lasts twice as long as a 2016.

Have a great day!
 
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If your battery is a 2016, you might see if you can get a 2020 or 2032 to fit in the holder; the difference is the thickness.

20xx is 20mm dia, and the xx16 is 1.6mm thick.

Typically, a 2032 lasts twice as long as a 2016.

Have a great day!
I always use 2032. Thanks. Have a great day (again, haha).
 
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Hi, i have a little issue, and i assume it's the CMOS battery. It happens randomly. But whenever i shut the PC down and plug it off the wall (because here in Argentina we have horrible electriciy companies and for safety i plug off the PC from the wall) the CMOS battery resets the BIOS to its defaults, time get stuck at the time i shut the PC down for the last time, but it keeps the profiles i saved. I remove the battery and i saw some dust in it, but just now i replaced with another one. The question is: Can the CMOS battery die or fail in 9 months, or can it be that it was a little bit dirty in the underside? I have a Maximus Hero XI WiFi with an i5-9600k. Thanks in advance!
A 3.3Volt battery will only save certain things, it will not save any settings such as an overclock. It will not keep current time as you unplug it(the wall plug does time) also internet does too. If you have dirty voltage you may consider a lap top, so it can be unplugged alot and still not have issue's such as your facing now.
 
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A 3.3Volt battery will only save certain things, it will not save any settings such as an overclock. It will not keep current time as you unplug it(the wall plug does time) also internet does too. If you have dirty voltage you may consider a lap top, so it can be unplugged alot and still not have issue's such as your facing now.
3.3 volt cmos battery absolutely will hold the rtc and mobo settings if unplugged, including and up to overclocking voltages and such.
 
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Leoplate25 said:
The question is: Can the CMOS battery die or fail in 9 months, or can it be that it was a little bit dirty in the underside?
Of course they can die in that short of time! I've even had dead batteries right out of the brand new package! But normally they last years. 3 - 5 years is normal but I've even seen them last 8 - 10.

As for the battery being dirty, maybe. That depends on how dirty and what the dirt was.
but just now i replaced with another one.
Good. But you may need to take it back out and clean it. When inserting these batteries, you should NEVER touch them with your bare fingers as skin oils promote corrosion and attract dust. So I always put a clean sock over my hand. If you touched the new battery with your bare fingers, it might need cleaning. And if the previous battery was dirty with grease/oil or other sticky contaminants, a good squirt with some quality electrical contact cleaner on the battery socket and contacts might be a good idea too.

Also, ALWAYS remember to unplug from the wall and touch bare metal of the case interior before reaching in to discharge any static in your body first.

3.3 volt cmos battery absolutely will hold the rtc and mobo settings if unplugged, including and up to overclocking voltages and such.
Except for them being 3.0V CR2032 batteries (not 3.3V - that's a PSU voltage), R-T-B is correct and the CMOS battery will indeed save OC settings. And one of its primary functions is to keep the RTC (real time clock) ticking when you unplug from the wall (or have a power outage). That's common knowledge so can only assume jaggerwild was tired and suffered from cranial flatulence when he said otherwise.

If you unplug from the wall (or flip the PSU master power switch to off) and your motherboard forgets the date & time (and boot order), the first thing you do is replace the CMOS battery.

And BTW, those lithium batteries should be recycled, not tossed in the trash. Here in the US, Best Buy will take them.
 
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Of course they can die in that short of time! I've even had dead batteries right out of the brand new package! But normally they last years. 3 - 5 years is normal but I've even seen them last 8 - 10.

As for the battery being dirty, maybe. That depends on how dirty and what the dirt was.
Good. But you may need to take it back out and clean it. When inserting these batteries, you should NEVER touch them with your bare fingers as skin oils promote corrosion and attract dust. So I always put a clean sock over my hand. If you touched the new battery with your bare fingers, it might need cleaning. And if the previous battery was dirty with grease/oil or other sticky contaminants, a good squirt with some quality electrical contact cleaner on the battery socket and contacts might be a good idea too.

Also, ALWAYS remember to unplug from the wall and touch bare metal of the case interior before reaching in to discharge any static in your body first.

Except for them being 3.0V CR2032 batteries (not 3.3V - that's a PSU voltage), R-T-B is correct and the CMOS battery will indeed save OC settings. And one of its primary functions is to keep the RTC (real time clock) ticking when you unplug from the wall (or have a power outage). That's common knowledge so can only assume jaggerwild was tired and suffered from cranial flatulence when he said otherwise.

If you unplug from the wall (or flip the PSU master power switch to off) and your motherboard forgets the date & time (and boot order), the first thing you do is replace the CMOS battery.

And BTW, those lithium batteries should be recycled, not tossed in the trash. Here in the US, Best Buy will take them.
@Bill_Bright : You are correct in stating that the CR2032 is rated at 3V but a new fresh battery is always more than 3V so 3.3V is a fresh battery. Another example is a car 12V battery that should be at 12.6-12.7V and needs an alternator to charge at 14V ( a greater amount than the battery can hold, you can't charge at 12v.)

A third example is a AA battery when fresh should be 1.57v or thereabouts.

A stated rated battery voltage is the lowest its rated for. They wear down from the over-volt and still remain in spec.
 
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@Bill_Bright : You are correct in stating that the CR2032 is rated at 3V but a new fresh battery is always more than 3V so 3.3V is a fresh battery. Another example is a car 12V battery that should be at 12.6-12.7V and needs an alternator to charge at 14V ( a greater amount than the battery can hold, you can't charge at 12v.)
True but not the point or pertinent to this thread. Just because a fresh or fully charged battery (assuming in good working condition) holds more than the rated voltage, it is NOT rated at that higher voltage.

A 12VDC car battery is still rated (and labeled) as a 12VDC car battery just as a CR2032 is rated and labeled as 3VDC and AA and AAA are rated and labeled as 1.5VDC (unless rechargeable - but that too is for another discussion).

Plus, in the case of that car battery, as soon as you remover the charger, the voltage will begin to drop and settle in around 12VDC.
you can't charge at 12v
Sure you can. You just will never get a "full" charge.

Also, as you noted, you are talking about fresh (new) or fully charged batteries. Batteries are only fresh, when fresh. So your points, while true, are really moot and irrelevant for the topic of this thread.
 
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The usual CMOS circuitry will hold info down to ~2.0V, some newer technology can go as low as ~1.6V, if the chip uses a 1.8V Vcc.

You need X number of diode drops to keep the internal circuitry biased properly; when it drops too low, it discharges the silicon capacitor thru the intrinsic diode inherent in how it's made.
 
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Sure you can. You just will never get a "full" charge.
CAN but won't: Only some kind of idiot would kill the battery prematurely that way.
 
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Nomenclature is what you're referring to as a 3V or 12V battery.

The actual cell voltage is based on chemistry, a "12V" car battery, minimally charged is 2.2V/cell, or 13.2V.
They tend toward 2.25V cell if fully charged, or slightly higher, depending on Exact chemistry.

That's why the "Full charge" setting on cars is 14.4V, and the 'Float" level is 13.6Volts.
These voltages vary with temperature; that's why they recommend to do an equalizing charge on your car batter every three months or so.
Never heard of that? That's why you buy new batteries every few years, lol.
Battery manufacturers no longer provide info to keep your battery healthy; they want you buying new ones regularly.

If you measure 12V on a 12V car battery, you might be walking soon. :)
That means it's heavily sulfated, if you are measuring it in your car.
And/Or your alternator is on it's way out.

For anyone interested, here's a good link. My car batteries last over 10 years, usually.


A Lithium primary battery at 3V is slightly discharged. It will decrease in the first few days to about 3v (2.9), and is considered dead at 2.7V, although for the purposes we're talking about here, there's a third of its life left.

If it doesn't measure at least 3.2V when you remove it from the package with a multimeter, it's an old battery.

Lithium Ion is 3.7V nominal, but will read 4.4V when removed from the charger, and is considered dead at 3V.
It's bad to let a li-ion battery totally discharge.

Back to the Topic: You can buy (or make) a CR123 Lithium primary battery with cables to plug onto the CMOS reset jumper, to override the battery on the motherboard; I haven't seen one in a while, but I know they exist. (Or used to)
That should last at least 10 years.

Make sure of the pinout of the reset jumper, it's usually "Battery, circuit, ground" but you want to be sure. :)
When you reset, you're removing the jumper from the battery to circuit connection, and connecting the circuit to ground.
The override battery should be - to ground, + to circuit.
 
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CAN but won't: Only some kind of idiot would kill the battery prematurely that way.
Huh? That will not kill a battery - especially a sealed lead-acid battery as used in cars since they do not suffer from memory effect. In fact, as long as the CCA rating is plenty big to turn the engine over on a cold day, there's no harm at all only charging the battery with an actual 12V charger. On a freezing cold morning, even a fully charged, brand new car battery will probably read below 12VDC anyway. After the car is started the alternator/charging system will top it off to ~14.2 to 14.6VDC.
If you measure 12V on a 12V car battery, you might be walking soon.
Nah! Not true at all. With a perfectly good battery, let your car sit for a week and you will see it drops to 12V or even a bit below. Why? Because that battery is still keeping your vehicle's clock and computer and security system alive and will do so weeks. Even if totally disconnected, some chemical reactions are still going on. But it has to have enough reserve to still start the car - and that's not a problem.

If what you suggested was true, I sure would have been stranded at the airport a couple hundred times during my career as I used to take lots of 7 - 10 day business trips. Never had to get a jump.

Edit comment: Inserted left out "day" after 10.
 
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Thanks, guys, for all the answers. I learned a lot of things that i didn't know. Cheers!
 
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