Maybe a silly question but I'd like to know as it's way outside my
knowledge base... :-)

On my old (28.5 years) SARPC, a long time ago I moved the CMOS battery
from the Mobo up into the gutter top side of the second slice.

I was wondering, did anyone ever write an app that would measure and
display the state of the CMOS battery, or even if that is possible?

Thanks
Dave

--

Dave Triffid

Dave <dave@triffid.co.uk> wrote:
> Maybe a silly question but I'd like to know as it's way outside my
> knowledge base... :-)
>
> On my old (28.5 years) SARPC, a long time ago I moved the CMOS battery
> from the Mobo up into the gutter top side of the second slice.
>
> I was wondering, did anyone ever write an app that would measure and
> display the state of the CMOS battery, or even if that is possible?

There's no sensors on the CMOS battery, so there's no way of reading it. If
you can stick a multimeter on it you can measure the terminal voltage which
gives you some idea of its state (dead or not), but it won't give you much
accuracy about future lifetime.

Unlike a phone or laptop, there's no 'gas gauge' monitoring hardware to
measure how much energy has gone out of it, and to add such monitoring to
such a small battery would end up draining the battery much faster so
there's no point.

You could put a digital voltmeter circuit on it so you could read the
voltage from software, but would need to design it so that it doesn't cause
additional drain.

Theo

In article <mGp*raDvz@news.chiark.greenend.org.uk>,
Theo <theom+news@chiark.greenend.org.uk> wrote:
> Dave <dave@triffid.co.uk> wrote:
> > Maybe a silly question but I'd like to know as it's way outside my
> > knowledge base... :-)
> >
> > On my old (28.5 years) SARPC, a long time ago I moved the CMOS battery
> > from the Mobo up into the gutter top side of the second slice.
> >
> > I was wondering, did anyone ever write an app that would measure and
> > display the state of the CMOS battery, or even if that is possible?

> There's no sensors on the CMOS battery, so there's no way of reading it.
> If you can stick a multimeter on it you can measure the terminal
> voltage which gives you some idea of its state (dead or not), but it
> won't give you much accuracy about future lifetime.

> Unlike a phone or laptop, there's no 'gas gauge' monitoring hardware to
> measure how much energy has gone out of it, and to add such monitoring
> to such a small battery would end up draining the battery much faster so
> there's no point.

> You could put a digital voltmeter circuit on it so you could read the
> voltage from software, but would need to design it so that it doesn't
> cause additional drain.

> Theo

Thanks for the info, appreciated.

I don't use the old SARPC very often these days, but I run it for a while
at least once week regardless...
So once a month while the SARPC is ON, I take the lid off and check the
rechargeable battery voltage is still okay.

That's all I really need to know. :-)

Dave

--

Dave Triffid

In message <5b04e8d6c1dave@triffid.co.uk>
Dave <dave@triffid.co.uk> wrote:

> In article <mGp*raDvz@news.chiark.greenend.org.uk>,
> Theo <theom+news@chiark.greenend.org.uk> wrote:
> > Dave <dave@triffid.co.uk> wrote:
> > > Maybe a silly question but I'd like to know as it's way outside my
> > > knowledge base... :-)
> > >
> > > On my old (28.5 years) SARPC, a long time ago I moved the CMOS battery
> > > from the Mobo up into the gutter top side of the second slice.
> > >
> > > I was wondering, did anyone ever write an app that would measure and
> > > display the state of the CMOS battery, or even if that is possible?
>
> > There's no sensors on the CMOS battery, so there's no way of reading it.
> > If you can stick a multimeter on it you can measure the terminal voltage
> > which gives you some idea of its state (dead or not), but it won't give
> > you much accuracy about future lifetime.
>
> > Unlike a phone or laptop, there's no 'gas gauge' monitoring hardware to
> > measure how much energy has gone out of it, and to add such monitoring to
> > such a small battery would end up draining the battery much faster so
> > there's no point.
>
> > You could put a digital voltmeter circuit on it so you could read the
> > voltage from software, but would need to design it so that it doesn't
> > cause additional drain.
>
> > Theo
>
> Thanks for the info, appreciated.
>
> I don't use the old SARPC very often these days, but I run it for a while
> at least once week regardless... So once a month while the SARPC is ON, I
> take the lid off and check the rechargeable battery voltage is still okay.
>
> That's all I really need to know. :-)

The only problem that you /might/ have is that once a month may or may
not be enough to make up for the discharge during the rest of the time.
It's not easy to calculate whether x minutes of use every y days is or
is not enough - and in any case you probably don't use it on a fully
predictable cycle.

In the end, all it means is that, if one day it doesn't boot up with
the correct settings, keep it powered on for a good few hours to charge
the battery up again.

Also, you may find it more useful to check the battery's voltage before
you switch on, rather than after, while it's charging.

David

In article <5463f2045b.DaveMeUK@BeagleBoard-xM>,
David Higton <dave@davehigton.me.uk> wrote:
> In message <5b04e8d6c1dave@triffid.co.uk>
> Dave <dave@triffid.co.uk> wrote:

[Snip]

> > Thanks for the info, appreciated.
> >
> > I don't use the old SARPC very often these days, but I run it for a
> > while at least once week regardless... So once a month while the SARPC
> > is ON, I take the lid off and check the rechargeable battery voltage
> > is still okay.
> >
> > That's all I really need to know. :-)

> The only problem that you /might/ have is that once a month may or may
> not be enough to make up for the discharge during the rest of the time.
> It's not easy to calculate whether x minutes of use every y days is or
> is not enough - and in any case you probably don't use it on a fully
> predictable cycle.

> In the end, all it means is that, if one day it doesn't boot up with
> the correct settings, keep it powered on for a good few hours to charge
> the battery up again.

> Also, you may find it more useful to check the battery's voltage before
> you switch on, rather than after, while it's charging.

> David

Generally good advice...

In my case, the running once a week is usually for at least four hours.

I usually test the voltage before starting the computer to get a truer
battery reading.
But then occasionally once the computer *is running* I take the battery
out of its holder and test it, and if it's showing signs of being a bit
low, I temporarily put another battery in the holder, then take the
rechargeable elsewhere to put it on charge for much longer.

Then when charged up, putting it back inside the (Obviously running)
computer.

I've been doing this for many years (15) and not *yet* lost any CMOS
settings.

Which is more than can be said about the number of times the VRPC CMOS has
gone crapola. :-)

No biggy of course, as any long time user of Virtual Acorns knows, keep
regular backups of the CMOS file. :-)

Dave

--

Dave Triffid

In message <5b054f0cf1dave@triffid.co.uk>
Dave <dave@triffid.co.uk> wrote:

> In my case, the running once a week is usually for at least four hours.
>
> I usually test the voltage before starting the computer to get a truer
> battery reading. But then occasionally once the computer *is running* I
> take the battery out of its holder and test it, and if it's showing signs
> of being a bit low, I temporarily put another battery in the holder, then
> take the rechargeable elsewhere to put it on charge for much longer.
>
> Then when charged up, putting it back inside the (Obviously running)
> computer.
>
> I've been doing this for many years (15) and not *yet* lost any CMOS
> settings.
>
> Which is more than can be said about the number of times the VRPC CMOS has
> gone crapola. :-)
>
> No biggy of course, as any long time user of Virtual Acorns knows, keep
> regular backups of the CMOS file. :-)

Clearly you have a good system in place!

David