If you're having frequent power outages, you might consider buying an UPS. Other than that, I'd just buy a new CMOS battery every few years. Mine seem to last way longer than 4 years. Maybe 8y or so.
I once worked on a product that you really did not want to have not coming back up. I was on it several years after the original engineers had designed an early model. Said engineers had not tested what happened when the CMOS battery died and triggered a reset of BIOS settings, brought it back to the hardware platform’s default state. When it did, the thing entered a non-bootable state. You could, with a serial port, access the BIOS and fiddle the settings back for one good boot…but the CMOS battery was non-removable, soldered to the motherboard. Our manufacturing process had not involved changing the default BIOS settings, just what was stored in CMOS. Oops.
IIRC our customer care guys just sent out new models for free to affected customers – the original hardware model wasn’t sold in large volume, and the cost of the actual hardware components wasn’t especially large relative to the cost of the product.
I had one sitting around on my desk, as it was sometimes handy to have a physically-accessible device to do work on. I rolled down to Radio Shack – yes, this was a few years back – got a removable CMOS battery case, stripped the non-removable battery out, soldered the battery case to the motherboard, and had the only instance of the device out there that could take a fresh CMOS battery.
The battery in smoke detectors should be changed every year and you should ideally test the detectors using the little button monthly.
In Norway we have an official smoke detector day which is on December 1. where we’re supposed to change the batteries. Its because Christmas is the high season for house fires.
That depends on the type of battery. I have some of the old school ones, which are “test every 6 months, replace every year,” but also a fancy schmancy lithium ion-powered one that should be good for 10 years (so test every 6 months, but replace after 10 years).
Yea the lithium-ion batteries are pretty good, you can also get 10 year smoke detectors with a built in lithium battery. Also a psa, smoke detectors usually only last 10 years and need to be replaced after that. There’s often an expiry date on the detectors.
Just took over a house last year with smart detectors connected to a homebase, all Li-Ion. Can see the battery percentage in the app. No more December 1st checks for a long time!
Lithium batteries last 5-10 years, regular 9v alkaline batteries last about 12-18 months. Some sources recommend changing the batteries every 6th month but i personally think that’s a bit excessive.
I only have a small 2 room apartment so i just got myself a cheap-ish optical smoke detector with a built in lithium battery. The battery should last 10 years which is how long smoke detectors last before they should be replaced.
Some BIOS manufacturers allow you to disable all halts on errors. As soon as you connect to the network your system should be able to sync its internal clock.
Not on a flash based motherboard (so basically almost everything recent). On modern systems usually the only thing the battery powers is the clock, which is why they have a separate reset to defaults header/button/switch.
(The CMOS memory of old is replaced with flash memory, al la SD Card or flash drive)
I agree with you about an uninterruptible power supply. While a computer’s Power supply can normally handle about half a second of the wrong voltage, a UPS should provide you with minutes to hours of run time. While that won’t solve the CMOS going bad, it would probably reduce the amount of times a power outage would last long enough to shut down the computer - though that absolutely depends on the reliability of power in your area.
Another option would be to look at different motherboard options. AsRock Rack (and I believe Supermicro) offer boards with BMCs, so you’d be able to change your BIOS settings from anywhere with a virtual KVM. They’re certainly pricier options, but a lovely convenience to have.
Discover that small UPS’s fail regularly, usually with cooked batteries.
Add maintenance routine for UPS battery.
Begin to wonder if this is really worth it when the rest of the house has no power during an outage.
Get small generator.
Discover that small generators also need maintenance and exercise.
Decide to get a whole house battery backup a-la Tesla Powerwall topped off by solar and a dedicated generator.
Spend 15 years paying this off while wondering if the payback was really worth it, because you can count on one hand the number of extended power outages in that time.
In the end times a roving band of thugs comes around and kills you and strips your house of valuable technology, leaving your homelab setup behind and - sadly - without power. Your dream of unlimited availability has all been for nought.
Conclusion: just replace the CMOS battery on a yearly basis during planned system downtime.
Yup. I don’t have a UPS (probably should; have a good surge protector though), and replacing CMOS batteries is way easier than dealing with the rest. Thanks for the reminder, I’ll go pick some up and swap it out every so often.
CMOS batteries last a lot longer than a year. Unless the system has been unplugged for a long time, they should be good for several years. I’m sure there’s actual data out there somewhere.
But yeah, a lot of people think “oh I’ll just put a UPS on it”. They don’t consider that unless you get a really big UPS, they’re only good for very short outages, seconds or minutes, to bridge the gap between the outage and your generator coming on (or the mains power coming back if it was just a flicker).
Also, the batteries in them need to be replaced every 3-5 years.
From what I can see, I just need to replace the CMOS battery. But this computer has been running for over 4 years, so what is stopping this from happening again around 2028?
Here’s the thing, you now know you’ve to replace the battery every 3 years or so, but I’ve SONY batteries running for 5 years and they’re fine. Now, your motherboard’s manufacturer is a piece of shit, the board should’ve just ignored the issue and proceeded to the OS. All modern operating systems sync the UEFI time whenever they get time from NTP so no need to halt the boot process.
The only real solution is to make this an extended maintenance task. The batteries are cheap so an alert every 4 years is likely sufficient to replace the battery before it dies. You could do it every 2 or 3 years instead at your discretion.
The only real solution is to make this an extended maintenance task.
This is the correct answer. No matter how reliable your power feed is you still need to reboot the server at some point for whatever reason and if CMOS battery is dead by then you’ll have the very same issue and you’ll need monitor and keyboard again. And even if you don’t mind about the RTC on board you’ll still lose the settings.
I wonder why manufacturers haven’t switched over to supercapacitors or something else than a coin cell battery, but perhaps there’s a valid reason for it. I think that supercaps can’t hold charge as long as a coin cell, but if your board is completely cold for a year or so maybe losing bios settings isn’t that big of a deal.
Well they still have a finite life and are less replaceable than a battery. Even if it quadrupled the lifespan (which is a reasonably generous estimate given OP’s 4-year duration and wikipedia telling me supercapacitors last 10-15 years), it would still eventually need to be replaced and that would generally require resoldering it.
I think a much better solution is 2 battery slots, one to be a backup battery, unused, and then when needed, an LED on the mobo can be turned on. Honestly OP could jury-rig up a similar system if he wanted to, although it’d be a bit ugly and anytime something is jury-rigged I don’t really think of it as reliable.
You could of course use some kind of socket or connetor for supercap, but as they last far less than I thought then I get why it doesn’t make sense. This thinkstation I’m writing with in my garage I got for free at old office is from 2011 and it’s still running original cmos battery. No idea if there’s any juice left on it, but at least it doesn’t complain anything at boot and once it refuses to boot it’ll become e-waste immediately (I do metal working, fix cars etc at the garage, so internals of this thing are far from clean, I think this is 3rd or 4th hardware for 10 years in here with only the SSD moved from setup to another).
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