Long lasting cr2032 alternative for motherboard - Page 1
Forum section: electronics / general

author: Kjelt
author_rank: Super Contributor
timestamp: August 03, 2024, 07:28:16 am
content: Intro:I always power up and shut down all equipment in the lab with heavy relays just as fire precaution and since energy has become quite expensive also to save a bit $.Issue:My pc's cr2032 battery goes empty within 10 months result in BIOS and clock setting each time. I have an Asus motherboard and the engineers thought it would be a great idea to put the batteryholder under the graphica card which takes me 22 minutes to replace.Alternatives:I purchased on aliexpress an empty cr2032 coin with undefined metal red and black wires badly soldered to them. Replaced the wires with decent 0.25mm2 copper Lapp cable and now I have the following alternatives and question:NiMH two cells 2.5-2.9 V will it be enough?Three cells 3.6 - 4.2 V will it be too much? Diode in series to drop the voltage?CR123 Lithium expensive how long will that last?Alkaline two cells: 2.6 - 3V leakage issues?What did YOU do or what would you choose?Anyone know the voltage limits for the mainboard chip?

author: Andy Chee
author_rank: Super Contributor
timestamp: August 03, 2024, 08:32:51 am
content: If your CR2032 is being drained in 10 months, then there is something wrong with your motherboard.(or you are purchasing poor quality CR2032 batteries from eBay)

author: nctnico
author_rank: Super Contributor
timestamp: August 03, 2024, 09:00:29 am
content: Quote from: Andy Chee on August 03, 2024, 08:32:51 amAgreed. A good quality CR2032 should last for about 10 years in a motherboard.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 03, 2024, 09:33:03 am
content: CMOS batteries for clock and settings data retention are normally not used when connected to the mains.This is because even when the computer is turned off, it is not completely disconnected; it is still supplied with standby power, which is used to maintain the clock and to process when the power button is pressed.When connected to the mains, the battery is automatically disconnected and operates on standby power. (This is an ambiguous term. It is actually similar, but different.)I would expect it to hold up fine if left alone for 10 years or so, but if it consumes it after less than a year, is the bad motherboard, is the battery of poor quality, or is it a design problem? I wonder.

author: coppice
author_rank: Super Contributor
timestamp: August 03, 2024, 09:38:37 am
content: Quote from: nctnico on August 03, 2024, 09:00:29 amMore specifically, the drain should be so low the lifetime is dominated by self leakage rather than the board's consumption. So, for a typical CR2032 you should expect a minimum of 10 years, even in a climate where the leakage is maximised. On the other hand, don't expect more than 15 years.

author: wraper
author_rank: Unknown
timestamp: August 03, 2024, 09:45:29 am
content: Quote from: nctnico on August 03, 2024, 09:00:29 am10 years is a little bit of a stretch in general IME, but it should last at least 5 years for sure.

author: janoc
author_rank: Super Contributor
timestamp: August 03, 2024, 10:15:52 am
content: Quote from: squadchannel on August 03, 2024, 09:33:03 amYou have missed literally the first line:QuoteSo there is no standby power.Quote from: Andy Chee on August 03, 2024, 08:32:51 amI have seen this problem with one of the Beelink mini-PCs that my mother has. The backup battery lasts there maybe a year. The motherboard is simply poorly designed and is drawing too much current from the battery.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 03, 2024, 10:22:30 am
content: Quote from: janoc on August 03, 2024, 10:15:52 amIf you replace it with a high quality battery and it still wears out, it's probably a bad design or a bad motherboard.Dallas NVRAM, that guy has a 10 year retension.

author: coppice
author_rank: Super Contributor
timestamp: August 03, 2024, 10:39:28 am
content: Quote from: wraper on August 03, 2024, 09:45:29 amThis can depend a lot on dirt. If a PCB collects a greasy film its surface can leak quite badly when moisture, dust and that grease work together. The electronics would be pretty badly designed to consume enough to keep the life down to 5 years.

author: tridac
author_rank: Regular Contributor
timestamp: August 03, 2024, 10:57:01 am
content: The solution here is to fit an AA battery holder to the side of the case, then use a 3.6v Lithium Thionyl Chloride, (eg: Saft LS14500), and never have to replace it again. Use the same for some older test gear that uses those aweful nicad rechargeables, that end up leaking all over the board.Sounds like you may have a hardware fault, but a larger battery might still help. Have you measured the current drain from the cell ?...

author: wraper
author_rank: Unknown
timestamp: August 03, 2024, 11:46:14 am
content: Quote from: tridac on August 03, 2024, 10:57:01 amIf original CR2032 was of a good quality, LS14500 will last about 8 years.

author: tridac
author_rank: Regular Contributor
timestamp: August 03, 2024, 12:08:35 pm
content: Yes, and there are C and D size cells of that type as well, though the 14500 will probably outlive the pc anyway....

author: MathWizard
author_rank: Super Contributor
timestamp: August 03, 2024, 02:48:22 pm
content: Quote from: nctnico on August 03, 2024, 09:00:29 amSo how is that possible though, what semiconductor's have such low leakage currents ? I would have guessed just the PCB materials or device leakage currents would drain a battery way way quicker. Or some internal issues that batteries have.I saw a cheap smoke detector once at a hardware store, that claimed it's battery would last ten years, and it wasn't mains powered. I didn't trust the claim. And usually there's some LED or test LED on a smoke detector, nevermind the buzzer. So yeah I'm sure it won;t last 10yrs if they are used at all.

author: wraper
author_rank: Unknown
timestamp: August 03, 2024, 02:57:32 pm
content: Quote from: MathWizard on August 03, 2024, 02:48:22 pmPCB leakage is less than insignificant (unless its surface is heavily contaminated). RTC/CMOS RAM drains a few uA at most. It it say drains 5uA, CR2032 should be good for 5 years.

author: wraper
author_rank: Unknown
timestamp: August 03, 2024, 03:01:39 pm
content: Quote from: MathWizard on August 03, 2024, 02:48:22 pmI don't know shit but they certainly lie

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 03, 2024, 03:16:40 pm
content: Finding and fixing a motherboard fault is hard, and probably expensive since replacement is probably the solution.One obvious solution would be to parallel your new connector with the existing one and then setting a maintenance schedule. Just add battery replacement to filter cleaning and all the other things you should be doing. With two batteries the interval should be well longer than a year, and as long as you don't take both out at once you won't have to redo bios settings, etc.Save the brainpower for more interesting stuff.

author: nctnico
author_rank: Super Contributor
timestamp: August 03, 2024, 03:25:34 pm
content: Quote from: MathWizard on August 03, 2024, 02:48:22 pmTypically there is some kind of dual power setup using diodes so when the PC is powered, the CMOS gets power from the mains supply. If the reverse diode has a lot of leakage, then it could drain the battery. It is also possible the diode and/or CMOS backup chip got damaged due to ESD when changing the battery and are leaking a lot now. Some measurements on the motherboard should be able to reveal what is wrong with it

author: coppice
author_rank: Super Contributor
timestamp: August 03, 2024, 03:29:16 pm
content: Quote from: wraper on August 03, 2024, 02:57:32 pmThe leakage of PCBs varies enormously. They are usually very low leakage, but I have seen some super leaky ones, with signals crosstalking all over the board. I assume those were bad batches. In one case I know it was due to moisture trapped between the FR4 and the solder mask on a large batch of boards. More common its dirty boards, especially in humid climates. Don't fall into the "it isn't a condensing atmosphere" trap. If there is any porosity or dust, that non-condensing atmosphere argument doesn't work. Having dealt with quite a lot of ultra low power stuff I say never discount board leakage until you have checked it out thoroughly.

author: Kjelt
author_rank: Super Contributor
timestamp: August 03, 2024, 03:30:17 pm
content: Quote from: squadchannel on August 03, 2024, 09:33:03 amThis is exactly the issue I cut mains fully off to the PC so there is no 3.3V standby power supply and the battery is 24/7 used. This is not a bad motherboard the quiescent current is large enough to drain a cr2032 if the pc is not used often.

author: Kjelt
author_rank: Super Contributor
timestamp: August 03, 2024, 03:32:37 pm
content: Quote from: tridac on August 03, 2024, 10:57:01 amGood idea, I will do that this afternoon.

author: magic
author_rank: Super Contributor
timestamp: August 03, 2024, 04:11:20 pm
content: Maybe two old fashioned non-rechargeable carbon-zinc AA cells? They are notorious for maintaining fairly constant open circuit voltage even if practically dead, maybe they will be OK for a light load like this for a few years.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 03, 2024, 04:28:45 pm
content: The quality of CR2032 cell is scattering. If it was just 1 cell or cells from the same pack, it could be just the battery quality.CR123 would probably be the next logical step up. Depending on the holder one may get an CR2050 in as well.

author: Kjelt
author_rank: Super Contributor
timestamp: August 03, 2024, 04:59:31 pm
content: Just measured 14uA consumption.With a 200mAh CR2032 that should be almost two years.Brand coincell was Grundig and they are pretty cheap so could be that the mAh is way less.

author: nctnico
author_rank: Super Contributor
timestamp: August 03, 2024, 06:41:27 pm
content: 14uA is way too much!

author: wraper
author_rank: Unknown
timestamp: August 03, 2024, 07:05:56 pm
content: Quote from: Kjelt on August 03, 2024, 04:59:31 pm14uA is a lot. Grundig is a Turkish shit brand for about two decades since it went bankrupt.

author: wraper
author_rank: Unknown
timestamp: August 03, 2024, 07:09:24 pm
content: Quote from: coppice on August 03, 2024, 03:29:16 pmIt must be very seriously deflective to make a noticeable difference in this context.

author: wraper
author_rank: Unknown
timestamp: August 03, 2024, 07:20:47 pm
content: I tested current on 4 (unpowered) motherboards out of curiosity. All had CPU installed except AM4 board.AMD AM2+ socket 3.8uA and 3.6uAAMD AM4 1.0uAIntel LGA 1555 1.6uA

author: coppice
author_rank: Super Contributor
timestamp: August 03, 2024, 07:31:40 pm
content: Quote from: wraper on August 03, 2024, 07:09:24 pmIf you work with ultra low power stuff its quite common to get complaints that the battery draw a customer sees is way above what you quote for your device. Then you go in, investigate, and find a variety of ways people manage to leak away 10 times what the chip takes

author: ejeffrey
author_rank: Super Contributor
timestamp: August 03, 2024, 07:46:52 pm
content: Quote from: wraper on August 03, 2024, 03:01:39 pmWhat? Of course they work. Smoke detectors take tiny amounts of current to operate. Even a standard smoke detector will run several years from an alkaline 9V battery. The 10 year ones have lithium batteries for low self discharge.The buzzer should go off for at most a few minutes in the lifetime of a smoke detector, it's a negligible load. Battery powered smoke detectors, if they have an LED, flash it with a very low duty cycle.

author: wraper
author_rank: Unknown
timestamp: August 03, 2024, 07:57:12 pm
content: ^It was sarcasm, just in case. Of course they normally last as claimed.

author: mariush
author_rank: Super Contributor
timestamp: August 03, 2024, 09:21:16 pm
content: You could get a rechargeable 2032 or 2020 cell and slowly charge it from the 3.3v of your computer during operation.Examples:https://www.digikey.com/short/nqt090w3ML2020 datasheet says charge at 2.8v - 3.2v (3.1v recommended) at 3mA or lower. So a 1n5817 diode in series with 3.3v will drop around 0.3v and then you could just add a resistor to limit the current to <mA, 1mA would be plenty to top up the cell.

author: richnormand
author_rank: Unknown
timestamp: August 03, 2024, 09:58:36 pm
content: Had a device (not motherboard) that worked well for about 10 years with its cell backup battery.Changed it and it lasted about 6 months. OK bad battery, tried again... same thing.Measured phantom current.... too high.Used "quick cool" spray while monitoring current.Culprit: bad electrolytic cap in a circuit across battery.Changed it to a good quality low leakage one and no issues for the past 8 years.

author: Benta
author_rank: Super Contributor
timestamp: August 03, 2024, 10:26:41 pm
content: Dumb question:are you sure the MB needs a CR2032 cell and not a ML2032 rechargable?If you're charging a CR2032, it's no wonder that it dies quickly.

author: Kjelt
author_rank: Super Contributor
timestamp: August 03, 2024, 10:45:00 pm
content: Quote from: Benta on August 03, 2024, 10:26:41 pmYes very sure, it is an asus strix z270f gaming motherboard it requires a CR2032 Lithium cell battery.

author: Halcyon
author_rank: Unknown
timestamp: August 04, 2024, 12:37:55 am
content: Quote from: nctnico on August 03, 2024, 09:00:29 amAbsolutely.

author: PlainName
author_rank: Super Contributor
timestamp: August 07, 2024, 07:06:04 pm
content: Quote from: Kjelt on August 03, 2024, 10:45:00 pmI have an Asus Strix Z270e and, like yours, it gets turned off every night (and sometimes daytime too). That is really off - single switch kills all mains to the PC and anything not needing active power when I'm not there. It is now seven years old and there is no problem (touch wood) with the backup battery.If yours is running out I would think the motherboard is at fault, even if you're using cheap and nasty batteries, since you shouldn't've had to replace the factory battery yet.

author: Kjelt
author_rank: Super Contributor
timestamp: August 07, 2024, 08:41:44 pm
content: Quote from: PlainName on August 07, 2024, 07:06:04 pmThanks probably indeed the case as the current consumption looks high.Anyway placed two AAA cells for now , replacing those every two years will be a piece of cake compared to having to remove the graphics card etc.Thanks everyone for the advice.