Can a CMOS battery die in a few months?

[Grog6]

I had to work hard to learn what I know; I don't mind sharing at all.
With Links and references, lol

Batteries all come down to their Amp-Hour capacity, all else is shapes and form factors.

And with Lithium, Fire!
Lol.

 

[Bill_Bright]

I had to work hard to learn what I know; I don't mind sharing at all.

Me too. And you can follow the link in my sig to see if I might know a little about electronics and how they work. And sharing what I know before those "little grey cells" decay away is why I come to forums like TPU.

And for the record, no one disputed your links and references. The only thing you said that I disagreed with was the comment about walking soon if your 12V car battery measured 12V.

BTW, if not a smoker, you might be interested in getting one of these for your vehicles. Very informative if your dash instrument panel only has an "idiot light" or does not include a gauge with actual numbers. It's a good suggestion for a stocking stuffer!

And yes, with lithium batteries often comes fire - not to mention explosions too. But sadly, that is often due to poor (or no!) quality control at the factory or improper matching to the electronics it is supposed to support. And those are typically the result of putting profit over safety.

 

[delshay]

I was thinking about doing an experiment & replace the battery with a coin type supercapacitor. Don't think it will be too hard to add-in the extra circuitry to charge the capacitor. This way I never need a battery.

On my to do list.

 

[Bill_Bright]

This way I never need a battery.

Never? Ummm, that depends on how long the computer might go without power. The cap, regardless its capacity, will eventually discharge completely if given enough time. There are all sorts of scenarios where a computer may go without power for extended periods. You might go on an extended vacation and unplug before you go or severe weather may take out power to your whole neighborhood for 10 days or longer - just to name a couple.

You wouldn't want the cap to be too big because you still may need to reset the BIOS by moving a jumper. You don't want sparks flying.

Technically, using a cap instead of a battery would not be hard. And from a design, parts and operation cost point of view, is probably cheaper than using a battery socket and battery. And of course, capacitors are not the environmental hazard Li-Ion batteries are. But is it a good idea? I would say no. If it was, surely motherboard designers would have done it long ago just to save on production costs.

 

[FordGT90Concept]

I had this problem with a MSI Neo 4 Platinum motherboard. Contacted MSI about it, did an RMA, and the new board (newer revision) didn't have the problem. Most likely there's a short circuit in the board that's causing excessive battery drain. It's not normal (CMOS battery should last > 10 years) and it will always kill batteries until it's physically replaced with a revision or different board that doesn't put excessive load on the battery.

 

[Space Lynx]

I ended up learning a lot from this thread, thanks OP... I always wondered about these little batteries lol

 

[potato580+]

no, evea fake one can worked well for years or so, ithink abt half quality of real product lifecyle, ive plenty on my office desk
sample of fake

 

[Bill_Bright]

I had this problem with a MSI Neo 4 Platinum motherboard. Contacted MSI about it, did an RMA, and the new board (newer revision) didn't have the problem. Most likely there's a short circuit in the board that's causing excessive battery drain.

(CMOS battery should last > 10 years)

No doubt the new revision had nothing to do with this. The old board had a faulty component (it happens) that, as you noted, caused resistance in that circuit to drop, causing excessive battery drain. By perfect timing on your part, the RMA simply coincided with there being a new revision. Either way, kudos to MSI for taking care of you! How a company takes care of their mistakes is one major factor in how we measure their reputation. If you didn't have to fight with them to get that RMA, then their reputation just rose a notch in my book!

As far as CR2032 batteries lasting 10 years, that would really depend on the demands put on the battery during its life. PCs that are never (or rarely) unplugged, never have their master power switch set to off ("0") or in those countries where wall outlets are switched, never have that power switched off, those batteries will certainly have a longer useful life.

But for PCs that, for most of their entire life span, are simply allowed to go into a standby state (which is any time the PSU is plugged into the wall, the master power switch remains set to on ("1"), and the wall outlet remains "live", the ATX Form Factor required +5Vsb standby voltage is still being delivered to the motherboard and that voltage, after being divided) is still used to keep the CMOS memory circuits, and the data contained within, alive without the help of the battery. No demands on the battery means a longer life.

But as newtekie1 correctly noted way back in post #6, the CR2032 batteries used on motherboards are not rechargeable. So if the motherboard goes through many periods of complete power outages, the battery will drain faster. So while 10+ years is certainly possible, 3 - 5 years is more the normal "expectancy".

Also, not all batteries are created equal. My personal experience has shown me it is worth the extra money to make sure I buy CR2032 batteries with that pink bunny is on the label, and not some off-the-wall brand or no-name generics.

 

[FordGT90Concept]

By perfect timing on your part, the RMA simply coincided with there being a new revision. Either way, kudos to MSI for taking care of you! How a company takes care of their mistakes is one major factor in how we measure their reputation. If you didn't have to fight with them to get that RMA, then their reputation just rose a notch in my book!

Bare in mind this was back in 2005.

As far as CR2032 batteries lasting 10 years, that would really depend on the demands put on the battery during its life.

Had a Pentium II machine which sat unplugged for over a decade and never had the battery replaced. It didn't lose its settings. A well engineered motherboard should make the CMOS battery last at least as long as the board itself does.

 

[Bill_Bright]

Bare in mind this was back in 2005.

Ah. Well things might have changed. Still Gigabyte treated me right back in the day when leaky electrolytic capacitors were wrecking havoc when they replaced a 4 year old mobo for free, 1 year after the 3-year warranty expired. To this day, they are my preferred motherboard brand and I suspect will remain so (until they don't treat me right!).

Had a Pentium II machine which sat unplugged for over a decade and never had the battery replaced. It didn't lose its settings. A well engineered motherboard should make the CMOS battery last at least as long as the board itself does.

I've seen them last that long too. But one or two examples do not make the rule. As I noted earlier, I've had brand new batteries that were bad straight out of the package.

I do, however agree with and feel they should last as long as the board itself - which, IMO, should be at least until I retire it due to obsolescence - not because it died.

 

[Grog6]

I was thinking about doing an experiment & replace the battery with a coin type supercapacitor. Don't think it will be too hard to add-in the extra circuitry to charge the capacitor. This way I never need a battery.

On my to do list.

There's problems with this.

The little battery stores more charge in its chemicals than a supercapacitor can hold, unless you're talking a big one.

If there's a short, something goes Boom! loudly.

Take this datasheet for example:

http://www.vishay.com/docs/28409/196hvc.pdf

This is for a larger coin cell type, rated for 4.2V and 90Farads.

According to the datasheet, it can supply 500uA for 24hours.
(There's a table on Page 8.)
Assuming things are linear, (big assumption, but it should be for power delivered to a load) 500uA for 24 hours, 20uA would be 25 days.

If the load is larger, the time is proportionally shorter.

Also, if you look up the leakage value of the supercapacitor, you'll find it's higher than the load you're going to put on it, so it's lifetime is self defined, not load defined.
There's a table for this, as well, Page 10.
It says that after power has been on for 20 or so hours, the leakage current stabilizes at about 20uA, which is as much as the load we would expect.

To make a long story short, (too late!) the little battery is going to outperform any supercapacitor 50x its size.

If you really want to build a charging circuit to recharge something, look into the 18650 Li-ion cells; I have a bunch of those, and they last a LONG time with small loads.
A 5800mAh cell will keep your mobo alive for a year, at least.

You can even buy a charging circuit cheap that would plug into a usb or molex power connector, that properly charges the cell.

A supercap story:
I worked with a tech that had the bright idea that he could replace his car battery with a huge supercap.

The big limits on those are:

• Temperature: Cars go to 180F+ easy under the hood; it's called "heat soak."
• Charging: Supercaps will draw hundreds of amps charging off an alternator; that's not good for either part.
• Discharging: Putting a starter motor across a capacitor is as close to a short as you will ever see. This was the "Nail in the Coffin", so to speak.

When dude hit the starter after driving around the parking lot and parking again, and everything heated up to high temperature, the battery-sized supercapacitor exploded, ruining the hood, radiator, and some other stuff from shrapnel.

So, be careful, and if you do decide to try using one, put the side of the case back on before you hit the power button, just to be safe.

 

[Leoplate25]

Keep learning stuff. Thanks, guys!

 

[Cjake]

Hey had the same kind of problem with both my monitors just going blank along with my mouse and keyboard shutting off, I then changed the cmos battery out and it all works again but I checked my old battery and from what I've read its still good reading 3v. Any ideas on what could've caused this to happen?

 

[Bones]

Hey had the same kind of problem with both my monitors just going blank along with my mouse and keyboard shutting off, I then changed the cmos battery out and it all works again but I checked my old battery and from what I've read its still good reading 3v. Any ideas on what could've caused this to happen?

Did you actually check the battery with a voltmeter to KNOW it still has 3.0v's?

Anything from below 2.9v's is bad enough to warrant changing it.
It seems from what you describe the BIOS settings got scrambled somehow and by removing the battery you caused it to reset to defaults which corrected the problem you had.
It's working again and that's the big thing here.