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Laptop CMOS Battery

M

Mike

Flightless Bird
When a laptop is disconnected from the mains and switched off does the
laptop keep time by using the "Normal" laptop battery, or does it go
straight to the CMOS battery to regulate the time ?

I ask this because as well as owning a laptop I have a desktop machine that
is 11 years old and still using the same CMOS battery. When I power down
the PC the fan stops etc but there is still a LED light lit on the circuit
board and I assume from this that the mains is still powering the clock.

DE
 
G

gargoyle60

Flightless Bird
On Fri, 8 Oct 2010 20:24:34 +0100, "Mike" <notme@here.com> wrote:

>When a laptop is disconnected from the mains and switched off does the
>laptop keep time by using the "Normal" laptop battery, or does it go
>straight to the CMOS battery to regulate the time ?
>
>I ask this because as well as owning a laptop I have a desktop machine that
>is 11 years old and still using the same CMOS battery. When I power down
>the PC the fan stops etc but there is still a LED light lit on the circuit
>board and I assume from this that the mains is still powering the clock.
>
>DE
>

I don't have a laptop but my desktop is about the same age and is rarely used, plus it is not
plugged into the mains power except for perhaps for ten minutes every two weeks. However, the CMOS
battery is the original and it still maintains the correct time and other BIOS settings.
 
M

mike

Flightless Bird
Mike wrote:
> When a laptop is disconnected from the mains and switched off does the
> laptop keep time by using the "Normal" laptop battery, or does it go
> straight to the CMOS battery to regulate the time ?
>
> I ask this because as well as owning a laptop I have a desktop machine that
> is 11 years old and still using the same CMOS battery. When I power down
> the PC the fan stops etc but there is still a LED light lit on the circuit
> board and I assume from this that the mains is still powering the clock.
>
> DE
>
>
Depends on the design. A typical system uses diodes to isolate the cmos
battery when power is available elsewhere.

Why is this important to you?
What are you gonna do about it either way?
When there's no solution, the answer is irrelevant.
 
M

mm

Flightless Bird
On Sun, 10 Oct 2010 01:58:37 -0700, mike <spamme0@go.com> wrote:

>Mike wrote:
>> When a laptop is disconnected from the mains and switched off does the
>> laptop keep time by using the "Normal" laptop battery, or does it go
>> straight to the CMOS battery to regulate the time ?
>>
>> I ask this because as well as owning a laptop I have a desktop machine that
>> is 11 years old and still using the same CMOS battery. When I power down
>> the PC the fan stops etc but there is still a LED light lit on the circuit
>> board and I assume from this that the mains is still powering the clock.
>>
>> DE
>>
>>
>Depends on the design. A typical system uses diodes to isolate the cmos
>battery when power is available elsewhere.
>
>Why is this important to you?
>What are you gonna do about it either way?
>When there's no solution, the answer is irrelevant.

You'll never make a good theoretical scientist. :)
 
M

mike

Flightless Bird
mm wrote:
> On Sun, 10 Oct 2010 01:58:37 -0700, mike <spamme0@go.com> wrote:
>
>> Mike wrote:
>>> When a laptop is disconnected from the mains and switched off does the
>>> laptop keep time by using the "Normal" laptop battery, or does it go
>>> straight to the CMOS battery to regulate the time ?
>>>
>>> I ask this because as well as owning a laptop I have a desktop machine that
>>> is 11 years old and still using the same CMOS battery. When I power down
>>> the PC the fan stops etc but there is still a LED light lit on the circuit
>>> board and I assume from this that the mains is still powering the clock.
>>>
>>> DE
>>>
>>>
>> Depends on the design. A typical system uses diodes to isolate the cmos
>> battery when power is available elsewhere.
>>
>> Why is this important to you?
>> What are you gonna do about it either way?
>> When there's no solution, the answer is irrelevant.
>
> You'll never make a good theoretical scientist. :)
HUH???
 
M

mm

Flightless Bird
On Sun, 10 Oct 2010 18:47:24 -0700, mike <spamme0@go.com> wrote:

>mm wrote:
>> On Sun, 10 Oct 2010 01:58:37 -0700, mike <spamme0@go.com> wrote:
>>
>>> Mike wrote:
>>>> When a laptop is disconnected from the mains and switched off does the
>>>> laptop keep time by using the "Normal" laptop battery, or does it go
>>>> straight to the CMOS battery to regulate the time ?
>>>>
>>>> I ask this because as well as owning a laptop I have a desktop machine that
>>>> is 11 years old and still using the same CMOS battery. When I power down
>>>> the PC the fan stops etc but there is still a LED light lit on the circuit
>>>> board and I assume from this that the mains is still powering the clock.
>>>>
>>>> DE
>>>>
>>>>
>>> Depends on the design. A typical system uses diodes to isolate the cmos
>>> battery when power is available elsewhere.
>>>
>>> Why is this important to you?
>>> What are you gonna do about it either way?
>>> When there's no solution, the answer is irrelevant.
>>
>> You'll never make a good theoretical scientist. :)
>HUH???

If you can say "When there's no solution the answer to a related
question is irrelevant", you seem to assume that it's not worth
learning something unless you already know what its practical benefit
is. Also you seemed to have assume there is no solution.

These attitudes are inconsistent with the needs of a theoretical
scientist, and some other roles too.
 
M

mike

Flightless Bird
mm wrote:
> On Sun, 10 Oct 2010 18:47:24 -0700, mike <spamme0@go.com> wrote:
>
>> mm wrote:
>>> On Sun, 10 Oct 2010 01:58:37 -0700, mike <spamme0@go.com> wrote:
>>>
>>>> Mike wrote:
>>>>> When a laptop is disconnected from the mains and switched off does the
>>>>> laptop keep time by using the "Normal" laptop battery, or does it go
>>>>> straight to the CMOS battery to regulate the time ?
>>>>>
>>>>> I ask this because as well as owning a laptop I have a desktop machine that
>>>>> is 11 years old and still using the same CMOS battery. When I power down
>>>>> the PC the fan stops etc but there is still a LED light lit on the circuit
>>>>> board and I assume from this that the mains is still powering the clock.
>>>>>
>>>>> DE
>>>>>
>>>>>
>>>> Depends on the design. A typical system uses diodes to isolate the cmos
>>>> battery when power is available elsewhere.
>>>>
>>>> Why is this important to you?
>>>> What are you gonna do about it either way?
>>>> When there's no solution, the answer is irrelevant.
>>> You'll never make a good theoretical scientist. :)
>> HUH???
>
> If you can say "When there's no solution the answer to a related
> question is irrelevant", you seem to assume that it's not worth
> learning something unless you already know what its practical benefit
> is. Also you seemed to have assume there is no solution.
>
> These attitudes are inconsistent with the needs of a theoretical
> scientist, and some other roles too.
>
Methinks you're the one making assumptions.
First thing I did was to opine the answer to the question.
Then I asked two questions.

I understand the importance of serendipity in
breakthrough theoretical discoveries.

As an engineer, I better appreciate the ability
to quickly eliminate likely nonproductive endeavors.

And a question for you...
Why does it matter to you, or the OP, whether I'll ever make a good
theoretical scientist???
 
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