Slightly OT: CR2032

[Robin]

Odd then that so many current motherboards have batteries which power the CMOS RAM - including from personal knowledge Z170 and Z270 chipsets.

[The Natural Philosopher]

That is normally simply to keep the RT clock going when the computer is switched off.

I did say battery backed RAM. I didn't say anything about the clocks.

In general the whole BIOS and its configuration these days is in FLASH RAM which is how you upgrade it.

I.e. when I take the battery out of my laptop. I lose the time, but I don't lose the bios settings.

Same goes for motherboards. The RTC may use an external battery, or one actually inside the chip package or a supercapacitor, that gets recharged every time the machine is switched on.

Since the RTC has less drain than a digital watch, the batteries are pretty much 'lifetime'.. in some cases you have to change the chip itself.

[Graham.]

Remember those Dallas chips? CMOS and non replaceable battery in a common DIL package. Stupid idea, but at least it was in a socket.

[Mike Tomlinson]

En el artículo , Bill escribió:

Common as muck

No reason at all. Ikea also do packs of 10 cr2032 for a quid.

[Mike Tomlinson]

En el artículo , Graham. escribió:

DS1287 and DS12887

They lasted about ten years though...

[Andy Burns]

Though they don't have an especially long shelf-life; a pack I bought this year is only in date until 2019, whereas some eBay specials I have already had for several years, are good until 2024.

[Graham.]

Maybe they were supposed to, but we found faliure so common (probebly within two or three years) that we carried a selecton of them in our spares kits. Maybe it was down to a bad batch of motherboards.

[Robin]

Some - especially laptops - have BIOS protected but you seem to be arguing that suppliers are lying about the role of batteries on motherboards as regards NVRAM generally. Eg

ASUS "The on-board button cell battery powers the RAM data in CMOS, which include system setup information such as system passwords"?

MSI: "There is CMOS RAM onboard that is external powered from a battery located on the motherboard to save system configuration data."

And IME removing the battery on such boards loses more than just the date and time.

[Jim GM4DHJ ...]

yes I stayed away from the mains PSU and made sure I didn't drop it........

[Dave Plowman (News)]

Depends. I'd probably buy just one from someone who shifted lots - like Boots or a supermarket. To get as fresh a one as possible. Such a pain to change I'd want one with the best life, rather than save pennies.

Then it wouldn't be a CR2032.

[Bill]

In message , Jim GM4DHJ ... writes

Thanks to all for the reassurance.

I have a huge stock of Poundland CR2032's because they come in packs of

4 with 2 CR2016's and I've used lots of these 2 at a time while fault finding the Jeep's key fob. The packs' expiry dates range from March 2016 to December 2017 which is a bit worrying but the ones I've checked measure 3.34 volts.

And as the old battery was dead I'll have to set the time anyway, so I'll power down and drop the batteries with wild abandon.

[Dave Plowman (News)]

They are on this Acorn RPC. But in practice, need replacing with about the same frequency as a lithium in a more modern machine. Say every 5-10 years.

[Bob Eager]

At the bottom:

[Dave Plowman (News)]

Be a pretty crappy desktop if you could get anywhere near mains inside it.

[Mike Tomlinson]

En el artículo , Robin escribió:

+1.

You used to be able to tell a failing battery - the clock would run slow. This was in the days before NTP, of course.

[Mike Tomlinson]

En el artículo , Andy Burns escribió:

I hadn't noticed, thanks for the heads-up.

are those specials, or "specials"? And how much do you trust the sell- by date on the "specials"? :)

Panasonic make the best, IMO, but you pay accordingly.

[PeterC]

2 years ago I replace the CR2032 in my 8 yo rig - and then built a new one 8 months later! On the ground that the PC had lasted that time on the original cell I didn't use an undated one from 7dayshop but slashed the cash and got a couple from Morrisons (of all places), Duracell dated 2024. Won't be wasted as I've 3 distros of Linux to try out.

[tabbypurr]

means almost nothing

good to go

[Harry Bloomfield]

Bill explained on 21/05/2017 :

Mine was down to 0.6v, the BIOS maintained by mains power. It refused to reboot, after the power was lost when they replaced the already smart meters :-)) I took me a good while to work out why it wouldn't boot up - because it was trying boot from its default of CD, then I spotted the time / date was years out and the penny dropped.

[Mr Pounder Esquire]

The battery in my pushing 10 year old desktop is working fine.