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View Full Version : real world battery times - 11" or 13" - your experience?




sbb155
Feb 10, 2011, 09:09 PM
How long does your MBA last, generally speaking, and under what conditions are you working?
For example is it: 11", surfing, 4-6 hours
or
13" - video, surfing, email - 5-5.5 hours

etc etc etc

I am considering the 13" after a bad experience with the 11" battery, but want to get objective numbers....
Thanks guys,
Samantha



shamash
Feb 10, 2011, 09:12 PM
I just got my 13", but I was downloading a torrent with uTorrent, had iTunes playing, had 2 microsoft word documents open, finder and settings open, Atlantis (a mud client) open, Adium and Good Chrome to browse the web, and it was at 80% with 4.5-5.5 hours left. (it went up and down as i switched between things, but didn't go below 4.5)

Its pretty sexy :D

bri1232001
Feb 10, 2011, 09:34 PM
Just because your mac says x hours left at y% battery does not mean thats what you'll get.

Is there an application that will track my time vs battery % and compare it to what the machine estimates. I'd like to know how long I'm actually getting from my battery per each lets say, 5% or 10% charge.

axu539
Feb 10, 2011, 11:01 PM
Just because your mac says x hours left at y% battery does not mean thats what you'll get.

Is there an application that will track my time vs battery % and compare it to what the machine estimates. I'd like to know how long I'm actually getting from my battery per each lets say, 5% or 10% charge.

From my experience, if the battery is properly calibrated, that is usually pretty accurate.

bri1232001
Feb 10, 2011, 11:07 PM
When it estimates 5 hours while I'm lightly surfing then yeah it likely is accurate. My usage is anything but constant though. I lightly surf, netflix for a bit (seems to really get my CPU going), open parallels briefly if I need to, then perhaps let the mac stay on while I read a homework problem and refer to an ebook on it.

For me the estimation is constantly changing as I use the program. It is also an "estimate" for a reason.

I guess I'm looking for a tracker or monitor, rather than an estimator.

shamash
Feb 10, 2011, 11:08 PM
From my experience, if the battery is properly calibrated, that is usually pretty accurate.

Agreed. Also want to point out that my battery seems to change due to temperature and other things. I was just outside with the MBA having Chrome, iTunes, Adium, Word, Atlantis and Textwrangler open. It was at 3 hours 30 minutes with 98%. I went back inside, it leaped to 4:38, then 5:02, and its still rising.

bri1232001
Feb 10, 2011, 11:10 PM
Agreed. Also want to point out that my battery seems to change due to temperature and other things. I was just outside with the MBA having Chrome, iTunes, Adium, Word, Atlantis and Textwrangler open. It was at 3 hours 30 minutes with 98%. I went back inside, it leaped to 4:38, then 5:02, and its still rising.

So you agree that yours is pretty accurate yet state that it varies by an hour and a half just from the location you are using it in!

Not in anyway the definition of accurate, that is unless the temp of the battery actually does have that drastic of an effect on its performance.

axu539
Feb 10, 2011, 11:19 PM
So you agree that yours is pretty accurate yet state that it varies by an hour and a half just from the location you are using it in!

Not in anyway the definition of accurate, that is unless the temp of the battery actually does have that drastic of an effect on its performance.

Actually, temperature probably does have some effect on the battery, since the battery does use a chemical reaction. However, in this case, it might just be that it's been so cold in many places that the sensors are being thrown off.

notjustjay
Feb 10, 2011, 11:20 PM
Not in anyway the definition of accurate, that is unless the temp of the battery actually does have that drastic of an effect on its performance.

Temperature does indeed greatly affect battery performance.

GGJstudios
Feb 11, 2011, 01:29 AM
Your battery indicator is a constantly-changing estimate, based on current power demands of your MBA. Calibrate your battery properly (instructions in the following link) to make sure the indicators are as accurate as possible.

This should answer most, if not all, of your battery questions:
Apple Notebook Battery FAQ (http://forums.macrumors.com/showpost.php?p=9875442&postcount=23)

tmoerel
Feb 11, 2011, 01:33 AM
Actually, temperature probably does have some effect on the battery, since the battery does use a chemical reaction. However, in this case, it might just be that it's been so cold in many places that the sensors are being thrown off.

Temperature has an influence yes. Recently i used my 13" somewhere where it was -15 degrees celsius. Normally i can use my machine for about 6 hours with wifi engaged and brightness at 50%.
With the cold it only lasted about 3 hours.

Xeperu
Feb 11, 2011, 01:38 AM
13" with 128GB SDD + 1.86 CPU = 7 hours of real world use. Light use, office + internet.

Screen at 40%. Bluetooth off, wifi off. (Airplane)

About 6 hours, same conditions but WiFi and Bluetooth on. With light browsing, sans Flash.

Whorehay
Feb 11, 2011, 03:34 AM
11" 1.6/4/128.

With pretty heavy Flash usage (for Google Finance charts), 50% brightness, bluetooth off, and with Microsoft Word/Powerpoint, Safari, and Adium running, we're looking at just about 5 hours, or about an hour per 19-21%. I would guess that heavier Safari usage would probably push it to 22-25% per hour of drainage.

A little less than my previous netbook (Dell Mini 10v) which could get a legit 6 hours of battery life, but obviously the MBA much more powerful, capable and much thinner.

impulse462
Feb 11, 2011, 07:25 AM
With moderate web-browsing, itunes, and light word processing with my screen brightness set to 25%, I received 6hrs and 31 minutes of battery life.

I'm assuming with my screen brightness set at 50%, I'd receive around 6 hours with the same usage.

neopickaze
Feb 11, 2011, 07:32 AM
With Spotify on WiFi, chrome with a few tabs, coda and mail open I get about 6 hours real world usage on my 13", brightness 2 notches down from maximum.

I know this is pretty accurate as I have the laptop on charge while I'm using it at work during my day job, then I do another 4 hours at the office (where I don't have a charger) and a couple of hours of iPlayer or other video streaming when I get home.

Thinking about it I probably do get about 7 hours usage from a charge.

I do use Coolbook with CPU undervolted to minimum but not underclocked so I think this has a hand, I'd probably get an hour less without it.

bri1232001
Feb 11, 2011, 11:31 AM
I do use Coolbook with CPU undervolted to minimum but not underclocked so I think this has a hand, I'd probably get an hour less without it.

So you see no performance loss yet better battery life by undervolting.
If undervolting is so great why isn't it done by default?

This leads me to believe there has to be some sort of consequence of undervolting.

2IS
Feb 11, 2011, 12:24 PM
So you see no performance loss yet better battery life by undervolting.
If undervolting is so great why isn't it done by default?

This leads me to believe there has to be some sort of consequence of undervolting.

Becasue not all processors are created equal. Some processors will work perfectly fine at a lower voltage while other processors even of the same model won't. Intel isn't going to test every single CPU die that comes out of their fabs so they simply over-volt all of them so even the worst of the bunch are stable. If you happen to have one of the crappy ones, you probably won't be able to undervolt much before the chip becomes unstable. C2D's are very mature now so it's rare that this would happen.