What is the battery used for in an Apple IIgs and is it needed?

[cb meeks]

Title pretty much says it all.

I just clipped the original batter off one of my IIgs's. I will eventually replace it with a more modern one (in a better, protective container).

But what was it used for? I assume TOD stuff in Apple GS OS? Do I have to have it if I don't care about TOD stuff?

[David Schmidt]

This post might be inappropriate. Click to display it.

[D Finnigan]

Post by David Schmidt

Post by cb meeks
Title pretty much says it all.

TOD and configuration RAM refresh. It remembers all your control panel
settings. If you're fine with the defaults as-is and you don't care
about the time, the battery is a no-op. Personally, I can't stand the
default blue screen and set it to black. I need the battery to remember
that for me.

On the IIgs with a dead battery I use Lithium to load those settings from a
file on disk. Doesn't restore time, of course.

http://macgui.com/downloads/?file_id=24771&keywords=lithium

[cb meeks]

Post by D Finnigan

Post by David Schmidt

Post by cb meeks
Title pretty much says it all.

TOD and configuration RAM refresh. It remembers all your control panel
settings. If you're fine with the defaults as-is and you don't care
about the time, the battery is a no-op. Personally, I can't stand the
default blue screen and set it to black. I need the battery to remember
that for me.

On the IIgs with a dead battery I use Lithium to load those settings from a
file on disk. Doesn't restore time, of course.
http://macgui.com/downloads/?file_id=24771&keywords=lithium
--
]DF$
http://macgui.com/newa2guide/

That's a good idea.

I thought about just running couple long wires to some type of enclosure that I feel confident that could withstand the corrosive acid from the battery. I like the idea of having the battery. I just don't want to leave it attached in storage.

More than likely I will just find a way of installing a removable battery and just try and remember to remove it before the computer goes in storage.

[Polymorph]

Post by cb meeks
I thought about just running couple long wires to some type of enclosure that I feel confident that could withstand the corrosive acid from the battery. I like the idea of having the battery. I just don't want to leave it attached in storage.

On my ROM 1 IIgs, I snipped the battery and replaced it with 3 rechargeable AAA batteries in series.

I bought the following (or similar) battery holders:
https://www.jaycar.com.au/2-x-aaa-pcb-mount/p/PH9264
https://www.jaycar.com.au/1-x-aaa-pcb-mount/p/PH9261

and soldered them to be in series. I hold the battery holders together with rubber bands (high tech!). Then the outputs are clipped to the old battery leads using alligator clips. I placed the battery holders beneath the power supply so that:
a) they are unseen; and
b) if they ever do leak, the damage will be minimal, and certainly won't affect my precious motherboard.

You can buy battery holders that take 3 batteries, but they don't stock those for whatever reason at Jaycar (local Australian electronics shop). Obviously a battery holder with 3 batteries would be ideal, and would involve less soldering! :-)

Anyway, hope this is helpful.

Cheers,
Mike
http://apple2.sytes.net/

[James Davis]

On Thursday, July 27, 2017 at 3:35:50 PM UTC-7, Polymorph wrote:
Obviously a battery holder with 3 batteries would be ideal, and would involve less soldering! :-)

https://www.jaycar.com.au/3-x-aaa-battery-holder-for-bike-light/p/PH9221

[Bill Garber]

"James Davis" wrote in message news:f709cce5-6fd7-4686-b7b0-***@googlegroups.com...

On Thursday, July 27, 2017 at 3:35:50 PM UTC-7, Polymorph wrote:
Obviously a battery holder with 3 batteries would be ideal, and would
involve less soldering! :-)

https://www.jaycar.com.au/3-x-aaa-battery-holder-for-bike-light/p/PH9221

And, these are used in those LED flashlights. ;-)

Bill Garber * http://www.sepa-electronics.com *

[Charlie]

Post by cb meeks

Post by D Finnigan

Post by David Schmidt

Post by cb meeks
Title pretty much says it all.

TOD and configuration RAM refresh. It remembers all your control panel
settings. If you're fine with the defaults as-is and you don't care
about the time, the battery is a no-op. Personally, I can't stand the
default blue screen and set it to black. I need the battery to remember
that for me.

On the IIgs with a dead battery I use Lithium to load those settings from a
file on disk. Doesn't restore time, of course.
http://macgui.com/downloads/?file_id=24771&keywords=lithium
--
]DF$
http://macgui.com/newa2guide/

That's a good idea.
I thought about just running couple long wires to some type of enclosure that I feel confident that could withstand the corrosive acid from the battery. I like the idea of having the battery. I just don't want to leave it attached in storage.
More than likely I will just find a way of installing a removable battery and just try and remember to remove it before the computer goes in storage.

I use a CR2032 coin type battery (the kind you see in nearly all
computers now days) in my ROM 01 IIgs. It's worked fine for years, it's
cheap and I've never seen or heard of one leaking.

I've seen holders for the CR2032 batteries for less than a dollar (US)
and if you are cheap like me then you get one off an old PC motherboard
that you are going to scrap anyway.

Charlie

[Anthony Ortiz]

Post by Charlie
I use a CR2032 coin type battery (the kind you see in nearly all
computers now days) in my ROM 01 IIgs. It's worked fine for years, it's
cheap and I've never seen or heard of one leaking.
I've seen holders for the CR2032 batteries for less than a dollar (US)
and if you are cheap like me then you get one off an old PC motherboard
that you are going to scrap anyway.
Charlie

Charlie, I'm sorry, but the only power source capable of generating 1.21 gigawatts of electricity is a Lithium 1/2 AA battery. Using a CR2032 would cause a temporal displacement at the junction point for the entire space-time continuum... I would tread carefully if I were you.

[Charlie]

Post by Anthony Ortiz

Post by Charlie
I use a CR2032 coin type battery (the kind you see in nearly all
computers now days) in my ROM 01 IIgs. It's worked fine for years, it's
cheap and I've never seen or heard of one leaking.
I've seen holders for the CR2032 batteries for less than a dollar (US)
and if you are cheap like me then you get one off an old PC motherboard
that you are going to scrap anyway.
Charlie

Charlie, I'm sorry, but the only power source capable of generating 1.21 gigawatts of electricity is a Lithium 1/2 AA battery.

You're thinking of the ROM 4. The ROM 01 only needs 1.20 gigawatts.

Post by Anthony Ortiz
Using a CR2032 would cause a temporal displacement at the junction point for the entire space-time continuum...

How do you think I got here. ;-)

Post by Anthony Ortiz
I would tread carefully if I were you.

We Apple II geeks are fearless. :-)

Charlie

[James Davis]

Post by Charlie
I use a CR2032 coin type battery (the kind you see in nearly all
computers now days) in my ROM 01 IIgs. It's worked fine for years, it's
cheap and I've never seen or heard of one leaking.
I've seen holders for the CR2032 batteries for less than a dollar (US)
and if you are cheap like me then you get one off an old PC motherboard
that you are going to scrap anyway.
Charlie

Another cool thing about Lithium Button Cell Batteries is that they recharge whenever you have your computer powered up (turned on). That's why they last for years in computers. But they do die quickly if you don't use your computer often. My first Slot-3-Clock battery lasted for over ten years. The second one only lasted about 5 years, up until 1997, because I stopped using my Apple IIe in late 1996.

[Charlie]

Post by James Davis

Post by Charlie
I use a CR2032 coin type battery (the kind you see in nearly all
computers now days) in my ROM 01 IIgs. It's worked fine for years, it's
cheap and I've never seen or heard of one leaking.
I've seen holders for the CR2032 batteries for less than a dollar (US)
and if you are cheap like me then you get one off an old PC motherboard
that you are going to scrap anyway.
Charlie

Another cool thing about Lithium Button Cell Batteries is that they recharge whenever you have your computer powered up (turned on). That's why they last for years in computers. But they do die quickly if you don't use your computer often. My first Slot-3-Clock battery lasted for over ten years. The second one only lasted about 5 years, up until 1997, because I stopped using my Apple IIe in late 1996.

CR2032 batteries are not rechargeable.
LR2032 batteries are rechargeable, but I don't believe the IIgs has a
charging circuit built in.

Attempts to charge CR2032 batteries could release the magic smoke rapidly.

Charlie

[Jorge]

Post by James Davis
Another cool thing about Lithium Button Cell Batteries is that they recharge whenever you have your computer powered up (turned on).

No, sorry, that's not so... unless you short circuit a diode and drive the pixies wisely into the battery (i.e. more circuits).

[Michael J. Mahon]

Post by James Davis

Post by Charlie
I use a CR2032 coin type battery (the kind you see in nearly all
computers now days) in my ROM 01 IIgs. It's worked fine for years, it's
cheap and I've never seen or heard of one leaking.
I've seen holders for the CR2032 batteries for less than a dollar (US)
and if you are cheap like me then you get one off an old PC motherboard
that you are going to scrap anyway.
Charlie

Another cool thing about Lithium Button Cell Batteries is that they
recharge whenever you have your computer powered up (turned on). That's
why they last for years in computers. But they do die quickly if you
don't use your computer often. My first Slot-3-Clock battery lasted for
over ten years. The second one only lasted about 5 years, up until 1997,
because I stopped using my Apple IIe in late 1996.

No, lithium primary cells (the kind we're talking about) *cannot* be
recharged. The battery circuit contains diodes to 1) prevent charging from
system power, and 2) prevent the battery from discharging through the
system.

While power is supplied, the battery does not supply current, prolonging
its life in systems that are on an appreciable part of the time, but no
recharging occurs. (Attempting to recharge a primary lithium battery/cell
is a good way to make it leak, if not worse.)

[James Davis]

Post by Michael J. Mahon
No, lithium primary cells (the kind we're talking about) *cannot* be
recharged. The battery circuit contains diodes to 1) prevent charging from
system power, and 2) prevent the battery from discharging through the
system.
While power is supplied, the battery does not supply current, prolonging
its life in systems that are on an appreciable part of the time, but no
recharging occurs. (Attempting to recharge a primary lithium battery/cell
is a good way to make it leak, if not worse.)

But diodes leak, a micro-current; if the battery voltage is lower than the voltage on the circuit, it gets recharged very slowly, until there is no more potential difference.

[Michael J. Mahon]

Post by James Davis

Post by Michael J. Mahon
No, lithium primary cells (the kind we're talking about) *cannot* be
recharged. The battery circuit contains diodes to 1) prevent charging from
system power, and 2) prevent the battery from discharging through the
system.
While power is supplied, the battery does not supply current, prolonging
its life in systems that are on an appreciable part of the time, but no
recharging occurs. (Attempting to recharge a primary lithium battery/cell
is a good way to make it leak, if not worse.)

But diodes leak, a micro-current; if the battery voltage is lower than
the voltage on the circuit, it gets recharged very slowly, until there is
no more potential difference.

Silicon diode leakage is tiny compared even to the normal backup current,
and so is insignificant. If charging current is desired (for a
*rechargeable* battery), a resistor must be installed in parallel with the
blocking diode.

For example, a typical clock/SRAM combo requires about 5 to 30 microamps to
retain time and data.

But typical blocking diode leakage is in the 0.025 microamp range.

So, if the battery charge/discharge efficiency is 100%, 1000 seconds of
"charging" by diode leakage is completely offset by about a *second* of
power-off backup.

In fact, the internal leakage of the battery is enough to completely negate
any charging by diode leakage.

So, no, diode leakage does not play any significant role in charging what
is, after all, a non-rechargeable battery.

Engineers are careful to prevent attempted charging of primary cells,
because it is damaging to the cell and, eventually, to anything in their
vicinity. ;-)

[James Davis]

Post by Michael J. Mahon
diode leakage does not play any significant role in charging what
is, after all, a non-rechargeable battery.

Who says simple lithium battery cells are not rechargeable? What is the chemistry?

Lithium-salt battery cells are not rechargeable; simple lithium battery cells are rechargeable, just like lead-acid cells are rechargeable. The chemical reaction is reversible. I don't think a button cell could last 10 years, let alone 5 years, if it wasn't rechargeable.

[Michael J. Mahon]

Post by James Davis

Post by Michael J. Mahon
diode leakage does not play any significant role in charging what
is, after all, a non-rechargeable battery.

Who says simple lithium battery cells are not rechargeable? What is the chemistry?
Lithium-salt battery cells are not rechargeable; simple lithium battery
cells are rechargeable, just like lead-acid cells are rechargeable. The
chemical reaction is reversible. I don't think a button cell could last
10 years, let alone 5 years, if it wasn't rechargeable.

Sorry, James, but lithium primary cells are *not* rechargeable. They last
10 years because they have very low internal leakage (self-discharge) rates
and they use a high energy density chemistry.

Check the manufacturers' specifications--you'll find that reverse
(charging) current is strongly discouraged.

Even if the chemistry is reversible, primary cells are not designed to keep
the reaction products in close proximity to the electrodes, so the
reversibility is very limited. Even more important, primary cells are not
designed to allow venting generated gasses, so leakage or explosion are
common results of charging attempts.

And then there's the fact that diode leakage is typically a thousand times
less than the backup load current--so ideal efficiency would result in a
thousand days of "charging" would result in one day of backing up the clock
and SRAM.

It's a primary cell that can supply backup power for about a decade, then
it must be replaced.

[James Davis]

Back in the day, I checked MY (the one I own) S.C.R.G. Slot-3-Clock card battery holder voltage, with and without the 3 volt (rechageable) LR2430 lithium battery, while powered up, and it was 5 volts. My lithium-air (LR) batteries were rechargeable and were recharged daily. That is why they lasted for so long.

Also, I was wrong about "simple lithum" batteries AND "lithium-salt" batteries. Their names are "primary lithium" batteries AND "secondary lithium-ion" or "lithium-polymer" batteries, respectively. And, I got thier rechargeabilities reversed. But, all of the following lithium battery chemistries are rechargeable.

Lithium battery

From Wikipedia, the free encyclopedia

<https://en.wikipedia.org/wiki/Lithium_battery>:

. . .

Disposable primary lithium batteries must be distinguished from secondary lithium-ion and lithium-polymer, which are rechargeable batteries.

. . .

Chemistries: [Chemistry, Cathode, Electrolyte, Nominal voltage, Open-circuit voltage, Wh/kg, Wh/L, and Comments.]

Li-V2O5, Vanadium pentoxide, <no data>, 3.3/2.4 V, 3.4 V, 120/260, 300/660, Two discharge plateaus. Low-pressure. Rechargeable. Used in reserve batteries.

Li-CuCl2, Copper chloride, LiAlCl4 or LiGaCl4 in SO2, a liquid, inorganic, non-aqueous electrolyte., <no data>, <no data>, <no data>, <no data>, <no data>, Rechargeable. This cell has three voltage plateaus as it discharges (3.3 V, 2.9 V and 2.5 V). Discharging below the first plateau reduces the life of the cell. The complex salt dissolved in SO2 has a lower vapor pressure at room temperature than pure sulfur dioxide, making the construction simpler and safer than Li-SO2 batteries., <no data>, <no data>, <no data>, <no data>, <no data>,

Li/Al-MnO2, Manganese dioxide, <no data>, 3 V, <no data>, <no data>, <no data>, <no data>, Rechargeable. Also known as ML type., <no data>, <no data>, <no data>, <no data>, <no data>,

Li/Al-V2O5, Vanadium pentoxide, <no data>, 3 V, <no data>, <no data>, <no data>, <no data>, Rechargeable. Also known as VL type., <no data>, <no data>, <no data>, <no data>, <no data>,

Li-Se, Selenium, non-aqueous carbonate electrolytes, 1.9 V., <no data>, <no data>, <no data>,

Li–air (Lithium–air battery), Porous carbon, Organic, aqueous, glass-ceramic (polymer-ceramic composites), <no data>, <no data>, 1800–660, 1600–600, <no data>. Rechargeable. No commercial implementation is available as of 2012 due to difficulties in achieving multiple discharge cycles without losing capacity. There are multiple possible implementations, each having different energy capacities, advantages and disadvantages. In November 2015, a team of University of Cambridge researchers furthered work on lithium-air batteries by developing a charging process capable of prolonging the battery life and battery efficiency. Their work resulted in a battery that delivered high energy densities, more than 90% efficiency, and could be recharged for up to 2,000 times. The lithium-air batteries are described as the "ultimate" batteries because they propose a high theoretical energy density of up to ten times the energy offered by regular lithium-ion batteries. They were first developed in a research environment by Abraham & Jiang in 1996. The technology, however, as of November 2015, will not be immediately available in any industry and it could take up to 10 years for lithium-air batteries to equip devices. The immediate challenge facing scientists involved in its invention is that the battery needs a special porous graphene electrode, among other chemical components, and a narrow voltage gap between charge and discharge to significantly increase efficiency., <no data>, <no data>, <no data>, <no data>, <no data>,

The liquid organic electrolyte is a solution of an ion-forming inorganic lithium compound in a mixture of a high-permittivity solvent (propylene carbonate) and a low-viscosity solvent (dimethoxyethane).

[Michael J. Mahon]

Post by James Davis
Back in the day, I checked MY (the one I own) S.C.R.G. Slot-3-Clock card
battery holder voltage, with and without the 3 volt (rechageable) LR2430
lithium battery, while powered up, and it was 5 volts. My lithium-air
(LR) batteries were rechargeable and were recharged daily. That is why
they lasted for so long.

We were discussing the 1/2AA primary lithium battery in the IIgs, which has
no charging circuit.

There were both types of clock peripheral cards for the slotted 8-bit
Apples: primary (usually 3 alkaline cells) and rechargeable (usually 3 NiCd
cells). The recharging cards had a resistor in parallel with the blocking
diode to set the charging current to (5v - 3.6v) / R.

Perhaps the most popular primary cell clock for 8-bit Apples is now the
Dallas Semiconductor ROM socket clock, sold for the Apple as the No-Slot
Clock. Primary lithium cell powered, it typically maintains time for about
ten years before battery exhaustion.

[James Davis]

Michael,

I guess I didn't delete that post soon enough. Please, ignore it and delete what I said from your post above. I intend to repost it after I have corrected my mistakes.

Sincerely,

James Davis

[Anthony Lawther]

Post by James Davis
Michael,
I guess I didn't delete that post soon enough. Please, ignore it and
delete what I said from your post above. I intend to repost it after I
have corrected my mistakes.
Sincerely,
James Davis

James,

Welcome to Usenet, where "deleting a post" doesn't really work even if
Google Groups would lead you to think that it does.

Regards,
Anthony.

[James Davis]

I was wrong about "simple lithium" batteries AND "lithium-salt" batteries. Their names are "primary lithium" batteries AND "secondary lithium-ion" or "lithium-polymer" batteries, respectively. And, I got their recharge-abilities reversed. But, all of the following lithium battery chemistries are rechargeable.

Lithium battery

From Wikipedia, the free encyclopedia

<https://en.wikipedia.org/wiki/Lithium_battery>:

. . .

Disposable primary lithium batteries must be distinguished from secondary lithium-ion and lithium-polymer, which are rechargeable batteries.

. . .

Chemistries:
==========================================================================================================
[Chemistry; Cathode; Electrolyte; Nominal voltage; Open-circuit voltage; Wh/kg; Wh/L; and Comments. . . .]
==========================================================================================================
Li-V2O5; Vanadium pentoxide; <no data>; 3.3/2.4V; 3.4V; 120/260; 300/660; Two discharge plateaus. Low-pressure. Rechargeable. Used in reserve batteries.
--------------------------------------------
Li-CuCl2; Copper chloride; LiAlCl4 or LiGaCl4 in SO2, a liquid, inorganic, non-aqueous electrolyte; <no data>; <no data>; <no data>; <no data>; <no data>; Rechargeable. This cell has three voltage plateaus as it discharges (3.3V, 2.9 V and 2.5 V). Discharging below the first plateau reduces the life of the cell. The complex salt dissolved in SO2 has a lower vapor pressure at room temperature than pure sulfur dioxide, making the construction simpler and safer than Li-SO2 batteries.
----------------------------------------------------------------------------------------------------------
Li/Al-MnO2; Manganese dioxide; <no data>; 3V; <no data>; <no data>; <no data>; <no data>; Rechargeable. Also known as ML type.
----------------------------------------------------------------------------------------------------------
Li/Al-V2O5; Vanadium pentoxide; <no data>; 3V; <no data>; <no data>; <no data>; <no data>; Rechargeable. Also known as VL type.
----------------------------------------------------------------------------------------------------------
Li-Se; Selenium; non-aqueous carbonate electrolytes; 1.9V; <no data>; <no data>; <no data>; <no data>.
----------------------------------------------------------------------------------------------------------
Li–air (Lithium–air battery); Porous carbon, Organic, aqueous, glass-ceramic (polymer-ceramic composites); <no data>; <no data>; 1800–660; 1600–600; Rechargeable. No commercial implementation is available as of 2012 due to difficulties in achieving multiple discharge cycles without losing capacity. There are multiple possible implementations, each having different energy capacities, advantages and disadvantages. In November 2015, a team of University of Cambridge researchers furthered work on lithium-air batteries by developing a charging process capable of prolonging the battery life and battery efficiency. Their work resulted in a battery that delivered high energy densities, more than 90% efficiency, and could be recharged for up to 2,000 times. The lithium-air batteries are described as the "ultimate" batteries because they propose a high theoretical energy density of up to ten times the energy offered by regular lithium-ion batteries. They were first developed in a research environment by Abraham & Jiang in 1996. The technology, however, as of November 2015, will not be immediately available in any industry and it could take up to 10 years for lithium-air batteries to equip devices. The immediate challenge facing scientists involved in its invention is that the battery needs a special porous graphene electrode, among other chemical components, and a narrow voltage gap between charge and discharge to significantly increase efficiency.
==========================================================================================================

The liquid organic electrolyte is a solution of an ion-forming inorganic lithium compound in a mixture of a high-permittivity solvent (propylene carbonate) and a low-viscosity solvent (dimethoxyethane).

. . .

[Delfs]

On the IIgs with a dead battery I use Lithium to load those settings from a file on disk.
Doesn't restore time, of course.

Has anyone made a network query that could be used to set the clock? Fire up the machine, load marinetti drivers, query the network and set the clock...

Hackfest anyone?

-Ed

[David Schmidt]

Post by Delfs

On the IIgs with a dead battery I use Lithium to load those settings from a file on disk.
Doesn't restore time, of course.

Has anyone made a network query that could be used to set the clock?

The Virtual Serial Drive sets the clock - but it's 8-bit.

[Antoine Vignau]

IIRC, Ewen Wannop wrote a network time utility, that should do the trick
av

[James Davis]

Post by Delfs

On the IIgs with a dead battery I use Lithium to load those settings from a file on disk.
Doesn't restore time, of course.

Has anyone made a network query that could be used to set the clock? Fire up the machine, load marinetti drivers, query the network and set the clock...
Hackfest anyone?
-Ed

There are several Time Sync websites like "time.nist.gov" that you can use.

[D Finnigan]

Post by cb meeks
But what was it used for? I assume TOD stuff in Apple GS OS? Do I have
to
have it if I don't care about TOD stuff?

Have you heard of PRAM in a Macintosh? It keeps alive the same settings, as
well as the real-time clock.

[Jorge]

Post by D Finnigan

Post by cb meeks
But what was it used for? I assume TOD stuff in Apple GS OS? Do I have
to
have it if I don't care about TOD stuff?

Have you heard of PRAM in a Macintosh? It keeps alive the same settings, as
well as the real-time clock.

And many Macs (some LCs and G4s) did not boot anymore with empty batteries... that wasn't funny at all.

[g***@sasktel.net]

Post by Jorge

Post by D Finnigan

Post by cb meeks
But what was it used for? I assume TOD stuff in Apple GS OS? Do I have
to
have it if I don't care about TOD stuff?

Have you heard of PRAM in a Macintosh? It keeps alive the same settings, as
well as the real-time clock.

And many Macs (some LCs and G4s) did not boot anymore with empty batteries... that wasn't funny at all.
--
Jorge.

Actually, they do. For a computer with a dead batery, Press the power button for a normal startup. Wait 30 secs. Power off, then immediately back on again.

This method has never failed me on any Mac.

[Michael 'AppleWin Debugger Dev']

Post by cb meeks
I just clipped the original batter off one of my IIgs's. I will eventually replace it with a more modern one (in a better, protective container).

Hmm, he asks _after_ he cuts the battery leads ...

:-)

Sorry, just giving you a hard time. :-)

[cb meeks]

Post by Michael 'AppleWin Debugger Dev'

Post by cb meeks
I just clipped the original batter off one of my IIgs's. I will eventually replace it with a more modern one (in a better, protective container).

Hmm, he asks _after_ he cuts the battery leads ...
:-)
Sorry, just giving you a hard time. :-)

LOL.

No worries. Yeah, I remove all batteries from my vintage computers. Those things are notorious for leaking all over the place. Capacitors are bad too but I just replace the electrolytic caps when I think it needs it.

Besides, I tested the battery at 0.8 volts so not much use letting it stay soldered on the board. lol

[James Davis]

Post by cb meeks
Besides, I tested the battery at 0.8 volts so not much use letting it stay soldered on the board. lol

Voltage is NOT an indication of battery life. You need to check it with a battery checker, not a voltage meter. The battery checker puts a (electrical current) load on it, also. If the current dies, the battery is (soon) dead!

[cb meeks]

Post by James Davis

Post by cb meeks
Besides, I tested the battery at 0.8 volts so not much use letting it stay soldered on the board. lol

Voltage is NOT an indication of battery life. You need to check it with a battery checker, not a voltage meter. The battery checker puts a (electrical current) load on it, also. If the current dies, the battery is (soon) dead!

Would putting an LED on it (even with a resistor) not do the same thing? That's usually how I test batteries.

[Michael J. Mahon]

Post by cb meeks

Post by James Davis

Post by cb meeks
Besides, I tested the battery at 0.8 volts so not much use letting it
stay soldered on the board. lol

Voltage is NOT an indication of battery life. You need to check it with
a battery checker, not a voltage meter. The battery checker puts a
(electrical current) load on it, also. If the current dies, the battery is (soon) dead!

Would putting an LED on it (even with a resistor) not do the same thing?
That's usually how I test batteries.

That typically provides a load of 5-20 milliamperes. OK for distinguishing
dead batteries from not-dead ones, but much more load than a clock/SRAM
battery will see, and much less than the battery would see in a flashlight
or toy.

[James Davis]

Post by cb meeks
Would putting an LED on it (even with a resistor) not do the same thing? That's usually how I test batteries.

IIRC, The load should match the type of battery (its internal resistance) being tested.

[Michael J. Mahon]

Post by James Davis

Post by cb meeks
Besides, I tested the battery at 0.8 volts so not much use letting it
stay soldered on the board. lol

Voltage is NOT an indication of battery life. You need to check it with
a battery checker, not a voltage meter. The battery checker puts a
(electrical current) load on it, also. If the current dies, the battery is (soon) dead!

But the OP was measuring the battery voltage while it was loaded
(in-circuit), so if the battery (lithium *cell*, actually) can't maintain
close to its specified voltage at its normal working current, its bad.

In this particular case, where the normal current supplied by the battery
is only a few microamps, most voltmeters will draw an additional microamp
per volt, so the battery voltage was actually being measured with an
additional load.

Bottom line: if a clock/SRAM battery has a measured in-circuit voltage
less than 80% of its rated voltage, it should be replaced.

-michael

NadaNet 3.1 and AppleCrate II
http://michaeljmahon.com