MacBook Air + Sleep = battery drain!

macboy4 · Jul 20, 2009

I have a MacBook Air rev B and I'm beginning to notice that my battery is draining quite a bit while in sleep mode. My PowerBook G4 NEVER dropped more than a couple of percent even if I left it unplugged in sleep for a couple of days. This leaves me with two questions:

1. Any idea what's causing this?

2. Is there a way to stop it from happening?

I travel a lot for work (hence the MacBook Air); I need to get this resolved before my next trip.

Thanks!

iBookG4user · Jul 20, 2009

This happened to me once on Saturday, I think it had something to do with bluetooth. So, I have since turned bluetooth off and haven't had the issue happen again.

jrwmba · Jul 20, 2009

I've noted the same thing on Rev. C 2.13. I have bluetooth off so at least in my case that is not it. Drain for me is a bit slower so I have not worried about it that much - anyone checked apple discussions?

iBookG4user · Jul 20, 2009

jrwmba said:
I've noted the same thing on Rev. C 2.13. I have bluetooth off so at least in my case that is not it. Drain for me is a bit slower so I have not worried about it that much - anyone checked apple discussions?

Was yours extremely hot temperature wise when it woke up? I checked the temps after it nearly burnt my fingers when I took it out of the bag and it said it was 164F and the battery was at 59%. This was after it being asleep for ~3 hours.

bobovic64 · Jul 20, 2009

Battery Drain

I have a Rev A and it has always done this. Temperature does not seem to be a factor.

plinden · Jul 20, 2009

macboy4 said:
I have a MacBook Air rev B and I'm beginning to notice that my battery is draining quite a bit while in sleep mode.

Define "quite a bit". There's always a certain amount of battery drain in sleep (my MBP drops about 2% during my one hour commute to and from work) and the G4s used a different sleep mode than the Intels.

If you set the hibernate mode to '1' it'll drain slower but it will be slower to wake.

See here - http://www.macworld.com/article/53471/2006/10/sleepmode.html

iBookG4user said:
Was yours extremely hot temperature wise when it woke up? I checked the temps after it nearly burnt my fingers when I took it out of the bag and it said it was 164F and the battery was at 59%. This was after it being asleep for ~3 hours.

Sounds like yours actually woke up in the bag for a period of time. This happened once with my MBP.

Mactagonist · Jul 20, 2009

Both the Rev A and B Macbook Airs as well as the late 2008 MBP I have owned suffered from this issue. They lost from 10-14% of the battery life overnight while sleeping.

The issue has been fixed in the early and mid 2009 MBPs. A full night will drain only 4%.

I do not believe it is related to 3rd party software as it is readily apparent even after a fresh reinstall of OSX.

whooleytoo · Jul 20, 2009

plinden's suggestion above is probably what you need - Macs can either sleep (using battery life, but waking very quickly) or 'deep sleep' (machine is off, but reverts to a saved state on wake). If your battery is draining a lot during sleep, it sounds like it's doing the former.

I use the Deep Sleep widget to set my MBP into deep sleep, you might take a look at that.

It is also possible some app/process is preventing the machine sleeping properly, in which case the machine would be quite hot (and battery drained a lot!) when you open it.

McGilli · Jul 20, 2009

I have a Rev B and mine loses 7% battery if I let it sleep overnight. so - that is about 12 hours.

Because of that I can never leave it just laying around - I have to leave it plugged into the AC all the time to make sure I have a full charge when i need it.

GeekGirl* · Jul 20, 2009

If its fully charged and when i get up in the morning and plug the charger in it says 1.20 minutes till full.

macboy4 · Jul 20, 2009

plinden said:
Define "quite a bit". There's always a certain amount of battery drain in sleep (my MBP drops about 2% during my one hour commute to and from work) and the G4s used a different sleep mode than the Intels.

If you set the hibernate mode to '1' it'll drain slower but it will be slower to wake.

See here - http://www.macworld.com/article/53471/2006/10/sleepmode.html

Sounds like yours actually woke up in the bag for a period of time. This happened once with my MBP.

I would define quite a bit as a couple of percent per hour. This isn't absolutely awful, but the beauty of sleep mode is that I can stay VERY portable with little time wasted. Taking a hit on my battery makes this less valuable.

Once on my PowerBook I left in sleep and unplugged for a few days and the loss was less than 10%.

I checked out the Macworld article, but it doesn't seem to indicate that the old sleep mode would use less power. Both the old and the new use RAM while asleep. It sounds as if it only affects the process while entering sleep and in the event of a total power loss so I guess I'm still not sure why the PowerBook was better. I may test out "0" and see how it works. Rarely do I enter sleep with unsaved info open so it's a minimal risk.

Thanks for all of the help guys!

macboy4 · Jul 20, 2009

So much for that! My MBA was at 75% 2.5 hours ago and now it's at 68%. That just seems like a lot; am I wrong?

timsutcliffe · Jul 20, 2009

I've just been away for the weekend, taking my MBA rev. A with me in sleep mode. I didn't use it once though, so it remained in sleep mode from Friday evening to Monday evening.

When I woke it in Monday evening, the battery was at 35%. So that's 65% lost in 72 hours, which I don't think is too bad.

faxao · Jul 21, 2009

The poor battery performance is the only negative remark I have to make about the otherwise perfect (IMHO) MBA. This is true not only for the sleep mode battery drain but also for the overall life span.
In my case (early 2009 Rev.B, bought at the end of January) after 58 recharge cycles I have got a poor 92% battery health (measured both with iStat and Coconut Battery). Not exactly what I would expect from a top line product!

whooleytoo · Jul 21, 2009

macboy4 said:
I checked out the Macworld article, but it doesn't seem to indicate that the old sleep mode would use less power. Both the old and the new use RAM while asleep. It sounds as if it only affects the process while entering sleep and in the event of a total power loss so I guess I'm still not sure why the PowerBook was better. I may test out "0" and see how it works. Rarely do I enter sleep with unsaved info open so it's a minimal risk.

That's not entirely correct. There is a "deep sleep" mode in which the machine is off, but with the RAM state saved to disk and restores this when it's "woken". In this state, you'd only expect a minor drain over a period of several days.

Jeffrosproto · Jul 21, 2009

My macbook's battery drains when it is in a light sleep. I think it's normal, as it has to keep power to the RAM.

macboy4 · Jul 25, 2009

Thanks for all of the responses! I broke down and called Apple Care. They had me do SMC and PRAM resets. It doesn't seem like that did anything. I'm still dropping about 2% an hour.

The thing that frustrates me is that I did NOT have this problem with my PowerBook. I've always had this problem with PCs so I saw this as a significant advantage over the Windows world.

Is it the Intel vs. PowerPC architecture that's the culprit here? Just a thought.

GeekGirl* · Jul 25, 2009

Not something to worry about love my air

Bill Gates · Jul 25, 2009

macboy4 said:
Thanks for all of the responses! I broke down and called Apple Care. They had me do SMC and PRAM resets. It doesn't seem like that did anything. I'm still dropping about 2% an hour.

The thing that frustrates me is that I did NOT have this problem with my PowerBook. I've always had this problem with PCs so I saw this as a significant advantage over the Windows world.

Is it the Intel vs. PowerPC architecture that's the culprit here? Just a thought.

I wonder if the default sleep mode is different between the two models. The MacBook air goes into sleep mode by default, where the machine is still providing power to the RAM. The PowerBook may have gone into safe sleep, where the machine is completely off, by default. Did your PowerBook take a few moments after waking it from sleep to come back to a useable state? What revision PowerBook did you have?

macboy4 · Jul 25, 2009

Bill Gates said:
I wonder if the default sleep mode is different between the two models. The MacBook air goes into sleep mode by default, where the machine is still providing power to the RAM. The PowerBook may have gone into safe sleep, where the machine is completely off, by default. Did your PowerBook take a few moments after waking it from sleep to come back to a useable state? What revision PowerBook did you have?

The PowerBook didn't go into safe sleep. It actually went to sleep faster than the MBA and woke up in the same amount of time. I tried switching the MBA into a different sleep mode, but it took >30 seconds to wake up. That just doesn't work for me. I may be trying to have my cake and eat it too, but I'm just frustrated that my older computer handled this better.

BTW I had the 1.5 GHZ 15"; it was the second to last G4 revision.

mrossi · Jul 25, 2009

macboy4 said:
The PowerBook didn't go into safe sleep. It actually went to sleep faster than the MBA and woke up in the same amount of time. I tried switching the MBA into a different sleep mode, but it took >30 seconds to wake up. That just doesn't work for me. I may be trying to have my cake and eat it too, but I'm just frustrated that my older computer handled this better.

BTW I had the 1.5 GHZ 15"; it was the second to last G4 revision.

The different sleep states don't really have anything to do with the processor, simply supplying power to the RAM as far as I understand it. Your Powerbook would have had less RAM probably (and a different type) so that might explain it.

You might also want to compare the battery capacity of your MBA vs Powebook.

macboy4 · Jul 25, 2009

mrossi said:
The different sleep states don't really have anything to do with the processor, simply supplying power to the RAM as far as I understand it. Your Powerbook would have had less RAM probably (and a different type) so that might explain it.

You might also want to compare the battery capacity of your MBA vs Powebook.

Interesting...

Both computers had 2GB of RAM, but the MBA's is DDR3. I'll have to look into the battery capacity.

joelypolly · Jul 25, 2009

Also powerbook had an additional battery

In pre-intel powerbooks there was an additional battery for the ram which allowed you to switch batteries without losing ram contents. After the switch to intel this battery was no longer available.

Most likely is that there was a difference between the intel and ppc architecture on how it managed interrupts (can be used to wake a computer). I would disable bluetooth wake and wake on LAN and see if there is any difference.

mrossi · Jul 26, 2009

joelypolly said:
In pre-intel powerbooks there was an additional battery for the ram which allowed you to switch batteries without losing ram contents. After the switch to intel this battery was no longer available.

Most likely is that there was a difference between the intel and ppc architecture on how it managed interrupts (can be used to wake a computer). I would disable bluetooth wake and wake on LAN and see if there is any difference.

wow, didn't know that! It certainly sounds like this explains the problem.

tempusfugit · Jul 26, 2009

timsutcliffe said:
I've just been away for the weekend, taking my MBA rev. A with me in sleep mode. I didn't use it once though, so it remained in sleep mode from Friday evening to Monday evening.

When I woke it in Monday evening, the battery was at 35%. So that's 65% lost in 72 hours, which I don't think is too bad.

Thats about twice as much battery loss as my MBP in the same amount of time. I've noticed about 10-15%/24hr

MacBook Air + Sleep = battery drain!

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