Battery drain during sleep

On 16-Apr-2007, at 15:18, Chris Pepper wrote:
> I called Apple to request a replacement battery, and the rep
> told me there was nothing wrong with losing 40% charge over 3 days
> asleep. What do others see for battery consumption while sleeping?

Tried Hibernating it? (er, I forget what Apple calls this, oh, right,
Safe Sleep).

Sleep the machine, wait until the light starts blinking (15-30
seconds), pop out the battery. Wait for the light to stop pulsing
and pop the battery back in.

If safe sleep mode is enabled, when you wake it up, it will be right
where you left it with a full charge.

On the other hand, I've never done this on an intel laptop.

<http://andrewescobar.com/archive/2005/11/11/how-to-safe-sleep-your-
mac/>

--
RTFM replies are great, but please specify exactly which FM to R

> I called Apple to request a replacement battery, and the rep
>told me there was nothing wrong with losing 40% charge over 3 days
>asleep. What do others see for battery consumption while sleeping?

1) What kind of shape is the battery in? That is, 40% of a new 100%
capacity battery is one things, but 40% of a battery in bad shape
(like 50% of its original capacity) is something else entirely.

As I am sure you know, many utilities will give you this information.
Coconut Battery and iStat Nano are two that I have on my MacBook Pro.

<http://www.coconut-flavour.com/coconutbattery/>
<http://www.apple.com/downloads/dashboard/status/istatnano.html>

2) Have you tried to recondition the battery to see if that has any
affect? (i.e. leave it in insomniac mode without power overnight
(down to demanding sleep, and 8 hours more) and then charge it up
overnight (to 100%, plus 8 hours more))

Just a guess.


--

=Alex Hoffman
Leadership Policy & Politics
Teachers College, Columbia University

On 4/16/07 3:18 PM, "Chris Pepper" <pepperreppep.com> wrote:

> I called Apple to request a replacement battery, and the rep
> told me there was nothing wrong with losing 40% charge over 3 days
> asleep. What do others see for battery consumption while sleeping?

That seems about in keeping with the drain I get on my Powerbook G4. Sleep
is hardly a panacea.

If you can't bear to turn your computer off (which saves the battery pretty
well), you may want to check for tips on how to force your computer to
hibernate and turn off rather than simply sleep. That gives power savings
equivalent to turning the Mac off, but provides a quicker start up which
puts you right back where you were, without having to re-open your
applications.

<http://matt.ucc.asn.au/apple/machibernate.html>

--
Nik :: gerberinik.net
Software picks, serious Mac geekery and productivity tips!
<http://iNik.net/>

On 4/16/07 at 2:18 PM, Chris Pepper <pepperreppep.com> wrote:

> I called Apple to request a replacement battery, and the rep
> told me there was nothing wrong with losing 40% charge over 3 days
> asleep. What do others see for battery consumption while sleeping?

That matches (or bests) my experience with a Powerbook G4; if mine
sleeps for 4 days, it's at risk of flat-lining the battery. (Or at least
that's my historical experience. I haven't clocked it with the
relatively new battery I received as part of the battery recall late
last year.)

- Todd

At 14:18 04/16/07 -0700, Chris Pepper wrote:
>I called Apple to request a replacement battery, and the rep
>told me there was nothing wrong with losing 40% charge over 3 days
>asleep. What do others see for battery consumption while sleeping?

I don't have a MacBook, but my HP Intel box can't sleep anywhere nearly
that long -- I think the limit is about 6-8 hours and the battery is dead.
The battery probably isn't in good shape, but still.

I don't know exactly what the power is used for during sleep, since it's my
understanding that the memory in laptops is static RAM. But they all do. As
already recommended, make it hibernate. Or find a way to thread the power
cord into the drawer.

Edward
--
Art works by Melynda Reid: http://paleo.org

On Apr 16, 2007, at 11:18 PM, Chris Pepper wrote:
> I called Apple to request a replacement battery, and the rep
> told me there was nothing wrong with losing 40% charge over 3 days
> asleep. What do others see for battery consumption while sleeping?

That seems excessive. I have an iBook G4 and it takes about two weeks
to drain completely when not in use. (I don't use it often.)

Kirk

              Read my blog: Kirkville -- http://www.mcelhearn.com
           Musings, Opinion and Miscellanea, on Macs, iPods and more

--On April 16, 2007 10:15:56 PM -0700 Edward Reid <edwardpaleo.org> wrote:

> I don't know exactly what the power is used for during sleep, since it's my
> understanding that the memory in laptops is static RAM. But they all do. As
> already recommended, make it hibernate. Or find a way to thread the power
> cord into the drawer.

Memory in laptops (and computers in general) is not static. Static memory
tends to be too slow for use as general memory in computers, especially
writing to memory. Flash memory is static memory.

Memory in computers at the moment is typically an SDRAM variant. Current
MacBooks use DDR2 memory in the SO-DIMM form factor. This type of memory
needs to be refreshed occasionally to maintain integrity.

<http://en.wikipedia.org/wiki/DDR2_SDRAM>
<http://en.wikipedia.org/wiki/SO-DIMM>

In sleep mode the hard drive is typically put to sleep and the memory still
refreshed. Waking a computer from sleep is nearly instantaneous. The CPU
may be put into a low power mode (but not shut off completely).
Connections to network services (i.e. mounted drives) maybe retained.

Hibernate (or safe sleep) writes the contents of memory to the hard drive,
and then memory is no longer refreshed and the CPU may be shut off
completely. The network card may remain awake on it's own if Wake-On-LAN
is enabled. When the computer is awakened, memory is read from disk back
into the memory chips and then picks up where it left off. Typically
network connections will be dropped, but sometimes they come back (depends
on time-out settings on the server).

You need at least as much hard drive space free as you have memory to use
hibernate mode. In Windows the system will typically reserve the necessary
space as soon as you enable hibernate (and sometimes at OS install)

At 10:15 PM -0700 2007/04/16, Alexander Hoffman wrote:
>> I called Apple to request a replacement battery, and the rep
>>told me there was nothing wrong with losing 40% charge over 3 days
>>asleep. What do others see for battery consumption while sleeping?
>
>1) What kind of shape is the battery in? That is, 40% of a new 100%
>capacity battery is one things, but 40% of a battery in bad shape
>(like 50% of its original capacity) is something else entirely.
>
>As I am sure you know, many utilities will give you this information.
>Coconut Battery and iStat Nano are two that I have on my MacBook Pro.
>
><http://www.coconut-flavour.com/coconutbattery/>
><http://www.apple.com/downloads/dashboard/status/istatnano.html>
>
>2) Have you tried to recondition the battery to see if that has any
>affect? (i.e. leave it in insomniac mode without power overnight
>(down to demanding sleep, and 8 hours more) and then charge it up
>overnight (to 100%, plus 8 hours more))

        Thank you all for the many useful suggestions. I tried a
bunch of battery gauges and like coconutBattery & iBatt2. They all
agree that my 5500mAh battery can only hold 3594mAh now. I'm sending
the MBP in for a screen flicker fix under AppleCare, and have asked
them to look at the battery. If they do not replace it this week, I
will drain it and (if it doesn't hold more charge afterward) request a
replacement.

--
Chris Pepper: <http://www.reppep.com/~pepper/>
                              <http://www.extrapepperoni.com/>
The Rockefeller University: <http://www.rockefeller.edu/>

Quoting Alexander Hoffman <ahoffmanaledev.com>:
> 2) Have you tried to recondition the battery to see if that has any
> affect? (i.e. leave it in insomniac mode without power overnight
> (down to demanding sleep, and 8 hours more) and then charge it up
> overnight (to 100%, plus 8 hours more))

Only nickel based batteries exhibit a memory conditioning that is
fixed by a deep discharge. Lithium based batteries, which most
PowerBook and MacBook laptops have, can be damaged by deep discharging.

<http://www.batteryuniversity.com/partone-16.htm>

>Only nickel based batteries exhibit a memory conditioning that is
>fixed by a deep discharge. Lithium based batteries, which most
>PowerBook and MacBook laptops have, can be damaged by deep discharging.
>
><http://www.batteryuniversity.com/partone-16.htm>

Apple Sayeth:

PowerBook G4 (15-inch Double-Layer SD), MacBook (all models), MacBook
Pro (all models), and MacBook Pro (17-inch) (all models)

The battery calibration for the PowerBook G4 (15-inch Double-Layer
SD) and any model of MacBook or MacBook Pro has been updated because
of a new battery released with this computer. With these computers,
follow these steps to calibrate your battery:

        1. Plug in the power adapter and fully charge your
PowerBook's battery until the light ring or LED on the power adapter
plug changes to green and the onscreen meter in the menu bar
indicates that the battery is fully charged.
        2. Allow the battery to rest in the fully charged state
for at least two hours. You may use your computer during this time as
long as the adapter is plugged in.
        3. Disconnect the power adapter with the computer still
on and start running the computer off battery power. You may use your
computer during this time. When your battery gets low, you will see
the low battery warning dialog on the screen.
        4. Continue to keep your computer on until it goes to
sleep. Save all your work and close all applications when the battery
gets very low, before the computer goes to sleep.
        5. Turn off the computer or allow it to sleep for five
hours or more.
        6. Connect the power adapter and leave it connected
until the battery is fully charged again.

Tip: When the battery reaches "empty", the computer is forced into
sleep mode. The battery actually keeps back a reserve beyond "empty",
to maintain the computer in sleep for a period of time. Once the
battery is truly exhausted, the computer is forced to shut down. At
this point, with the safe sleep function introduced in the PowerBook
G4 (15-inch Double-Layer SD) computers, the computer's memory
contents have been saved to the hard drive. When power is restored,
the computer returns itself to its pre-sleep state using the safe
sleep image on the hard drive.

<http://docs.info.apple.com/article.html?artnum=86284>

--

=Alex Hoffman
Leadership Policy & Politics
Teachers College, Columbia University

At 06:04 04/18/07 -0700, Kevin van Haaren wrote:
>Memory in laptops (and computers in general) is not static. Static memory
>tends to be too slow for use as general memory in computers, especially
>writing to memory. Flash memory is static memory.

We can have warring Wikipedia cites:

    http://en.wikipedia.org/wiki/Static_RAM

A quick search indicates that you are right about static memory no longer
being used even in laptops.

However, you are wrong to call static RAM slow. In general, static RAM is
faster, and uses less power, than dynamic RAM. It's also less dense and
more expensive. But the CPU cache in your computers is almost certainly
static RAM -- for speed.

The distinction between static and dynamic RAM is whether it requires
refreshing and thus uses power just to preserve its contents (dynamic). Any
RAM which does not require power to preserve its contents is called static.
Today this apparently includes RAM which needs voltage to hold its
contents, as long as there is no power drain. So the term "static RAM" is
broad enough to include flash memory, CPU cache memory, and core (which a
good many here remember).

I do still think that static RAM was used in early laptops due to its lower
power requirements. But the computer world has moved on so fast that
verifying this with a web search is difficult at best.

So it appears that the battery drain in sleep mode is for refreshing the
DRAM. This is what we get for larger and cheaper memories: limited sleep
time. With SRAM, the sleep time would be either indefinite, like
hibernation (SRAM not requiring voltage) or limited only by the simple
decay of the charge on the battery (SRAM requiring voltage). And why do we
need larger memories? To run software which requires it. And why does the
software require it? Because we have it, or are willing to buy it to run
the software. Break this cycle and the world economy collapses.

Edward
--
Art works by Melynda Reid: http://paleo.org

> At 06:04 04/18/07 -0700, Kevin van Haaren wrote:
>> Memory in laptops (and computers in general) is not static. Static
>> memory tends to be too slow for use as general memory in computers,
>> especially writing to memory. Flash memory is static memory.

<old fart warning />

For all practical purposes all semi memory used in computers years ago
was static. And it cost a fortune. Dynamic was developed and was a big
hit as it used far less "silicon" than static which means that memory
for a computer 20 or 30 years ago cost as much as a decent car instead
of a house.

But dynamic has to be refreshed every so often or it forgets. And to
refresh it you had to read the data then write it back. To make this not
take forever the memory was organized into rows and columns (logically)
and you could read/write entire rows at a time. But of course when doing
this, everything else that wanted memory had to wait. When it first came
out and for a while these refresh circuits were hard to build and get
right. If you squeezed too much for higher performance you lost data. If
you went too safe, you had a slower computer than the competition.
Dynamic memory control was the bane of many early "build it yourself"
pcs. It was just hard to get it all working correctly.

Now almost every computer design includes a chip set that has built into
it the memory refresh logic to handle all of this. Life is much more
simple now.

And the main driver as to dynamic vs static is still costs. Dynamic is
incredibly cheap compared to static. Basically a transistor and a
capacitor to hold a bit. Much more for static.

David Ross

On 4/19/07 at 5:26 AM, edwardpaleo.org (Edward Reid) wrote:

>The distinction between static and dynamic RAM is whether it
>requires refreshing and thus uses power just to preserve its
>contents (dynamic). Any RAM which does not require power to preserve
>its contents is called static.

Close but not quite correct. Any RAM that doesn't need to be
refreshed is considered static.

The difference between SRAM and DRAM with respect to battery
discharge is a difference of how fast the battery discharges.
DRAM must be actively clocked in order to refresh the memory. To
clock any circuit, there must be other circuitry that is
dynamically changing between on/off states. It is this dynamic
switching that significantly increases power consumption.

For SRAM, there will be a consumption of a few picoamperes per
bit. The actual current will be determined by the leakage
currents of the transistors that form each memory cell. So, if
you have a machine with say 1GB of SRAM, you can expect at least
~10 mA will be needed to maintain that memory.

>Today this apparently includes RAM which needs voltage to hold its
>contents, as long as there is no power drain.

If you need a voltage to hold contents, there will be a power drain.

>So the term "static RAM" is broad enough to include flash memory, CPU
>cache memory, and core (which a good many here remember).

There is another term used to describe memory which needs no
power at all to retain data which is "non-volatile". Since
non-volatile memory is made using distinctly different
technologies than SRAM it is not common to label non-volatile
memory as "static" RAM. In fact, doing so causes confusion since
there will be a power drain to maintain the contents of SRAM.