Question on amp hour battery capacity measuring

Hello,
I am trying to measure a lithium ion two cell battery for amp hour capacity. I can get the value by running the battery down to the lowest recommended charge level and this gives me the amp hour value, but how do I calculate what the amp hour would be if I only discharge to 80%?

I doubt that you will find an expert on Li battery discharge models here, Google may help
http://www.google.com.sg/search?sclient=psy&hl=en&source=hp&q=lithium+ion+capacity+cycles+modelling&...
-AK2DM
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"It’s the questions that drive us.”
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Similar Messages

Measure battery capacity (not battery meter)?

Is there an app that measures the battery capacity (i.e. shows the maximum charge it can hold), and compare it to a new ipod touch's battery? If such app exists it would probably require you to fully charge the device and then let it discharge for a while.
I'm not looking for a battery meter, which shows only the current charge.

Hi Kappy,
I got your point. However, I'm talking about capacity here(Watt hours), which is commonly expressed as mWh and for MacBook Pro it should be 60000 mWh, but mine shows 55000 mWh. Here are the specs for MacBook Pro http://www.apple.com/macbookpro/specs.html
I'm referring to Windows porgram just because I'm not that much familiar with Mac OSX yet...but more I use it, more I like it
P.S. Current Voltage is 12.436V and it does change from 9.8V to 12.65 depending on whether the battery is being drained down or charged.

I am looking at buying a MacBook Air over the Pro mainly for the 12 hour battery. Just wondering if battery is compromised by upgrading to 8mb and upgrading to I7 Intel dual core. I am not very tech savvy so apologies if dumb question

I am looking at buying a MacBook Air over the Pro mainly for the 12 hour battery. Just wondering if battery is compromised by upgrading to 8mb and upgrading to I7 Intel dual core. I am not very tech savvy so apologies if dumb question

If both computers were configured identically, then they would both lose the same amount of battery life with respect to the same starting configuration - comparing apple to apples. I don't know how much the added RAM, etc. would reduce battery life, but it would be less for both models.
Battery life is a tricky subject because most mfgr.s like to suggest as long a life as possible, but often do so under a set of conditions that are not common to most users. Apple is no different. Their computers do have good battery life, however. But not likely as long as what is in the ads for the typical user.

Battery Capacity Question

This morning my battery capacity was at 48% after I calibrated it over night due to the system profiler telling me to "check battery." After using my computer for a little while without it being plugged in, my battery was down to about 45min remaining for power. Then I closed the lid and put it to sleep. After about an hour I opened it and immediately the message popped up saying that my computer was running on reserve power and I should plug it in. Now, my current battery capacity is at 26%.
Does anyone know why this has happened? Should I just get a new battery?
Thanks!

It means that you most likely need a new battery. If your computer is still under warranty then bring it there. If it's out of warranty, then you might have to pay. If your battery has less than 300 charge cycles then you can ask if they are willing to replace it for free or a minimal charge since Apple said their battery should held 80% life after 300 cycles.

Since I upgraded to iOS 7.0.4 on my iPad 3, battery capacity has drained almost 10%/hour without any use of the device. Prior to the upgrade, the battery charge would hold during periods of inactivity. What can I do to solve this significant problem?

Since I upgraded to iOS 7.0.4 on my iPad 3, my battery capacity has drained almost 10% per hour without any use of the device. Prior to the upgrade, the battery charge would hold during periods of inactivity. What can I do to solve this significant problem? Is there a way to uninstall iOS 7.0.4 and return to the previous version?

Downgrading isn't supported.
You can poke around in the settings. There's a lot of stuff defaulted to on that you may not need, such as notifications.
You can also look into background app refresh and background app updates. They can be running in the background and drain your battery.

Fluctuating Battery Capacity

Yesterday my MBP had a funny turn relating to it's recognised battery capacity. I had been using it for most of the day on fairly boring tasks and I was running it on battery power when all of a sudden it shut down on me. I plugged in charger and fired it up and when I looked at the battery it was at 0% however the capacity had fallen by over 75%.
Originally it was about
93% of original
4440mAh
270 load cycles
10months old
All of a sudden it was
16% of original
762mAh
I used System Profiler and Coconut to check the levels.
I left it charging for a couple of hours until it said it was full then I turned it off. I let it cool, took the battery out, dusted it, polished it and put it back.
When I turned the machine back on the battery capacity was back to 93% original.
The basic question is has anyone seen this before? Quickly followed by software glitch or intermittent hardware fault.
Cheers for any help.

The design capacity of a new battery is often exceeded slightly by its actual capacity. You got a good one.
My late-2008 MBP's battery has a design capacity of 4600 mAh, but it started off at about 4800 and still has never gone as low as 4600, after 11 months and 64 cycles. Right now it shows 4622.
It isn't possible for your MBP to have operated on battery power for 24 hours without sleeping. Something is wrong, not with your battery but with your story.

Concerned about falling battery capacity on rMBP

Hello all, I'm starting to worry a bit about my battery capacity vs design capacity on my retina macbook pro 15". It's a early 2013 model that I bought in July. I know that apple guarantees the battery will have at least 80% of it's design capacity after 1000 cycles, but I'm worried mine is going to fall far short of that. Here's my coconut battery info:
As you can see, I've only had 60 cycles on the battery, the computer is barely half a year old, and it's already down 6%, under 8000 mAh. Should I be concerned/take it to the apple store? I know they won't replace my computer since I'm far outside of my 14 days, but still wondering if they'll do something. Will they even do anything before the battery falls below 80% design capacity?
I waited to post because I know battery capacity often fluctuates from 5% below to 5% above design frequently and will go up and down with use, but mine has steadily decreased, and has never increased. Every time I check coconut battery, it's 10-50 mAh lower than it was. My macbook does stay plugged in a lot, but I also make a point of using the battery at least once a week to keep the electrons flowing, and most weeks it gets off the charger more like two or three times. Often the battery will get used down to at least 50 or 60 percent before it gets plugged back in, sometimes even as low at 15 or 20 percent. I've tried draining it until it goes to sleep and then letting it charge to full again, but it didn't change anything. I didn't think it would, since lithium based batteries don't suffer memory issues, but I thought maybe it was just an error in measurement by the system.
Speaking of that, I did reset the NVRAM/PRAM and the SMC (multiple times). Only one of the times I reset the SMC did the light turn orange and then charge more, but it didn't change the max capacity number at all.
I see a lot of people posting their cocunut results/system information screen and finding they actually have above design capacity. Did I just get a lemon battery, or is it because I have it plugged in so much?
Thoughts? Thanks!

Apple guarantees that if your battery is well taken care of and not abused, however your battery looks fine.
You state: ~ As you can see, I've only had 60 cycles on the battery
Cycle counts dont account for much. People (some) leave their macbooks always hooked on power and worse still in sleep mode and on power and this can ruin a battery in "50 cycles", ergo it means little.
As for the 5% power fluctuation this means absolutely nothing since charge is just an estimate and the 5% is within that range.
Information:
Bad discharging or battery use conditions:
Heat (due to environmental conditions or due to rapid discharges from heavy use = gaming / video editing)
Rapid discharging of the battery frequently causes chemical changes over time in the battery leading to decrease capacity and resistance of current flow.
The very worst use of your battery is often draining the battery very low, and worse still letting it remain in such a state.
*Most long-term rapid damage to the battery occurs from discharging it with high loading (gaming) conditions but paramount is avoiding deep and frequent low DOD (depths of discharge) in use.
Undesirable charging or charged conditions:
High perpetual SOC (state of charge), where the battery is always or very often connected to charge
Parasitic loading where the battery is both usually on and charging or worse both always charging and in sleep mode, since this induces mini-cycling of the battery.
Bad general handling conditions:
Temperature use conditions when either too hot (95F and above) or too cold (50F and below)
Storing your battery away with a low charge (40% and less) long-term.
Considerations:
Your battery is subject to chemical aging even if not in use. A Lithium battery is aging as soon as its made, regardless.
In a perfect (although impractical) situation, your lithium battery is best idealized swinging back and forth between 25 and 85% SOC (state of charge) roughly.
Further still how you discharge the battery is far more important than how it is either charged or stored short term.
Ultimately counting charge cycles is of little to no importance. Abuse in discharging (foremost), charging, and storing the battery and how it affects battery chemistry is important and not the ‘odometer’ reading, or cycle counts on the battery.
Everything boils down to battery chemistry long term, and not to an arbitrary number, or cycle count.
Keep your macbook plugged in when near a socket since in the near end of long-term life, this is beneficial to the battery.
http://www.apple.com/batteries/notebooks.html
"Apple does not recommend leaving your portable plugged in all the time."
General rule to remember of Lithium batteries is:
Never drain them LOW & dont always/often store them HIGH
While cycle count is commonly seen to be the “miles” on your Lithium Ion pack cell in your Macbook, which they are, this distinction is not a fine line at all, and it is a big misconception to “count charge cycles”
*A person who has, for example, 300 charge cycles on their battery and is recharging at say 50-60% remaining of a 100% charge has better battery usage and care than another person who has 300 charge cycles at say 15% remaining on a 100% charge.
DoD (depth of discharge) is far more important on the wear and tear on your Macbook battery than any mere charge cycle count. *There is no set “mile” or wear from a charge cycle in general OR in specific.    As such, contrary to popular conception, counting cycles is not conclusive whatsoever, rather the amount of deep DoD on an averaged scale of its use and charging conditions.
(as a very rough analogy would be 20,000 hard miles put on a car vs. 80,000 good miles being something similar)
*Contrary to some myths out there, there is protection circuitry in your Macbook and therefore you cannot overcharge it when plugged in and already fully charged
*However if you don’t plan on using it for a few hours, turn it OFF (plugged in or otherwise) ..*You don’t want your Macbook both always plugged in AND in sleep mode       (When portable devices are charging and in the on or sleep position, the current that is drawn through the device is called the parasitic load and will alter the dynamics of charge cycle. Battery manufacturers advise against parasitic loading because it induces mini-cycles.)
Keeping batteries connected to a charger ensures that periodic "top-ups" do very minor but continuous damage to individual cells, hence Apples recommendation above:   “Apple does not recommend leaving your portable plugged in all the time”, …this is because “Li-ion degrades fastest at high state-of-charge”. This is also the same reason new Apple notebooks are packaged with 50% charges and not 100%.
LiPo (lithium polymer, same as in your Macbook) batteries do not need conditioning. However...
A lot of battery experts call the use of Lithium cells the "80% Rule" ...meaning use 80% of the charge or so, then recharge them for longer overall life.
Never let your Macbook go into shutdown and safe mode from loss of power, you can corrupt files that way, and the batteries do not like it.
The only quantified abuse seen to Lithium cells are instances when often the cells are repeatedly drained very low…. key word being "often"
The good news is that your Macbook has a safety circuit in place to insure the battery doesn’t reach too low before your Macbook will auto power-off. Bad news: if you let your Macbook protection circuitry shut down your notebook at its bottom, and you refrain from charging it for a couple days...the battery will SELF-DRAIN to zero (depending on climate and humidity)…and nothing is worse on a Lithium battery being low-discharged than self-draining down to and sitting at 0
Contrary to what some might say, Lithium batteries have an "ideal" break in period. First ten cycles or so, don't discharge down past 40% of the battery's capacity. Same way you don’t take a new car out and speed and rev the engine hard first 100 or so miles.
Proper treatment is still important. Just because LiPo batteries don’t need conditioning in general, does NOT mean they dont have an ideal use / recharge environment. Anything can be abused even if it doesn’t need conditioning.
From Apple on batteries:
http://support.apple.com/kb/HT1446
http://www.apple.com/batteries/
Storing your MacBook
If you are going to store your MacBook away for an extended period of time, keep it in a cool location (room temperature roughly 22° C or about 72° F). Make certain you have at least a 50% charge on the internal battery of your Macbook if you plan on storing it away for a few months; recharge your battery to 50% or so every six months roughly if being stored away. If you live in a humid environment, keep your Macbook stored in its zippered case to prevent infiltration of humidity on the internals of your Macbook which could lead to corrosion.

2 day old MacBook Pro at 98% battery capacity

I'm a little bit concerned about the lifespan of my new MacBook Pro's battery. When i recieved the machine i performed a battery calibration as Apple recommends. I then charged and discharged again. I was concerned when Coconut battery (not always accurate) told me my battery was at 98% total capacity. Is this normal? after 2 cycles my capacity is down 2% .
I'm surprised because I've never seen this on my old iBook which usually loses 1% capacity per month.
I've read that these lithium ion batteries have a memory, that the cells not being used stop functioning because they are not needed. Is this true?
When at home should i keep the machine plugged in? My iBook used to be fine when i took it to school and drained it, then charged it at night. Opinions?

More or less, yes, I do. Actually turns 5-days old today and at 97.8% of capacity (5330 mAh compared to 5450 when new) after 4 battery loadcycles. Coconutbattery says this is 97%, but my math is a bit higher at 97.8%. Clearly this rate of decline is not sustainable.
So my question to you was, did "don't worry, enjoy" mean that in your experience, the initial few percentage points of battery capacity is blown off quickly, but the battery capacity will quickly stabilize to something that is still acceptable?
My battery on a full charge this morning (day 5 of ownership) lasted 3:50, with display at 50%, no use of the optical drive, Wifi on, bluetooth off, and running Mail, Safari, Firefox, iCal, Excel & Activity Monitor (to keep an eye on things). No work was done in Excel, Firefox or iCal, just Mail & Safari. So, I, too, am a bit concerned about being nowhere near 7 hours. Or 5 hours, for that matter. So, short battery life and losing 2.2% of capacity in 4 loadcycles and 5 days is concerning, and tempting to connect the dots.

20 month old MBP with only 80% battery capacity

Been noticing my 09 alu uni body 13" MBP now has a battery capacity of just 80%, according to Coconut Battery. I realise this app might not be too accurate, but I only checked it as I've been noticing a reduction in battery life recently.
I've been using MB's for years and employ all the usual good practices, I also regularly recalibrate the battery, although I understand these new non-replaceable models don't require it, nonetheless, it can do no harm.
My question is, is such a reduction in the batteries capacity normal on this machine after just 20 months use?
BTW- The use consists of running on mains at work during working hours, resting over night during the week, use on battery/mains at home at the weekend. According to Coconut the battery has had 348 cycles. Again, no idea how accurate this app is!
I have 3 years cover on the machine, so it it's deemed this is not usual I can pay the Apple store a visit, but I'd be interested in the views of other users whether this is normal or not.
Thanks.

If you think that's necessary. But losing 20% capacity in almost 2 years is pretty good for any battery. It's just that we can monitor it more accurately now.
You can get your current capacity vs design capacity via Terminal without coconut:
ioreg -l | grep Capacity
^that's a -L and then a |

I calibrated my battery but the battery capacity hasn't increased.

I calibrated my battery but the battery capacity hasn't increased. My computer's battery life is still at 1 hour 30 minutes when others have gotten upwards of two hours. What do I do?

Calibrating the battery does not alter its capacity, it just allows the MacBook system software to be more accurate in telling you how long you have left before the battery is exhausted.
So… Is there a discrepancy between the time-remaining estimate shown in the battery / power menu? When you allowed the battery to drain as part of the calibration process, did you check how many lights lit on the battery itself at the time of exhaustion? In general, how many lights on the battery are lit when the Mac believes the battery is exhausted? How many when it believes it is fully charged? Lastly, use the System Profiler ( → About This Mac → More Info…) and check to see what is the stated battery capactiy, in mAh (milli-amp-hours). The nominal capacity is 5500. (As a reference point, my system has been within 10 or 20 mAh of this value ever since I got it.)
If all those things are consistent, then your battery really has diminished capacity and you should replace it, or get Apple to replace it for you.
On the other hand, if the battery's capacity is normal (close to the nominal 5500 mAh), then probably the way you're using the MacBook just is just very draining of battery power.
Randall Schulz
iMac 20" Core Duo; MacBook Pro Mac OS X (10.4.6)

MBP Original Battery Capacity?

I have a 9 month old (June 2009) 17" MacBook Pro5,2 with the new built-in long life battery (the battery is not user replaceable). I think the battery is faulty as battery life from fully charged to empty seems significantly reduced.
"About This Mac" reports battery full charge capacity at 8783 mAh, battery condition as "Check Battery" and cycle count for this battery is 65
iStat Pro reports battery health at 64%.
coconutBattery doesn't work for this model MBP as it's reporting original battery capacity at 1300 mAh.
How can I find out what the original battery capacity was so that I can compare current capacity with original capacity?

G'day Stolds, and welcome to the forums.
Your 17" came with a battery which Apple specify as a "95 Watt hour" battery.
The "nominal voltage" for the battery in the 17", used when converting from Watt hours to mAhs is 7.3V. (unlike the 15" and 13" which have a 10.8v battery)
P=vi (Watts = volts x amps)
Therefore i (amps)=P (watts)/v (volts)
95/7.3 = 13 Amps (roughly)
Multiply by 1000 to get mA
so this is a battery with roughly 13000 mAh capacity when new.
The non-removeable batteries in the unibody MBPs are rated to maintain 80% of original maximum capacity for 1000 cycles .
Your battery is way below par, and clearly defective. Take it in and get it replaced under warranty.
Cheers
Rod

Battery capacity after 10 weeks only 90% ??

Hello community!
I hope I'll get some information here, since I am a new mac user
Hope you guys can help?!
Here's the thing: I got my macbook pro in october 2010 (mid 2010 model)
I've been using coconut capacity monitor since the beginning and always monitored the battery life. Yesterday I noticed, that coconut says battery capacity is 90% of the original capacity! Coconut says that I did around 48 load cycles so far.
my question: What am I doing wrong here? I always try to work with the mbp until it runs out of battery; I don't plug it in before, no charging when the battery is not completely empty. How can it happen, that the capacity reduces that fast?
What should I do in order to preserve the battery life? Is it possible to restore the 100% battery capacity by recalibrating it several times (like the apple support page advices) ??
Thank you for you answers and your help in advance!!
Kind regards,
griesTraum

With 48 load cycles in only ten weeks, you're working your battery very hard. And always running the battery down to zero before recharging it is a bad practice that will age your battery prematurely. If your work and lifestyle don't require you to consume the full capacity of the battery almost daily, don't do it.
It's not unusual to see the battery's reported Full Charge Capacity (and consequently its "health") fluctuate up and down by several percentage points from day to day and week to week, particularly when it's relatively new. If you give the battery at least a little use every few days, it should be calibrated every two or three months. Calibrate it now or as soon as it's convenient for you, then try to keep it plugged into AC power most of the time, using the battery for just an hour or two every day or two "to keep the electrons moving," as Apple says. This will be an ideal use pattern for the longevity of your battery. If it doesn't fit your life, don't do it: the battery exists to serve you, not you to serve it.
The best summary of useful information about MBP batteries that I know of is here:
http://discussions.apple.com/thread.jspa?threadID=1764220
If after following these suggestions for a few weeks, your battery's health continues to decline steadily and rapidly, you may have a defective battery. But until it shows less than 80% health, you're unlikely to get anything from Apple other than a report that it is "within specifications." So if you think it may be defective, wait until it shows 75-78% health for a least a week or two, and continues to show less than 80% after a new calibration. Then take it to an Apple Store, where they have a specific test they can run on it, and ask to have it tested. If it's defective, you'll get a free replacement.

MacBook Pro Mid 2010 Battery Capacity

I've read a few threads about this, mostly about battery capacity rapidly dropping after an install of ML. I installed ML when it first came out, and just noticed the drastic decrease in battery life about 3 weeks ago. My capacity could have potentially been dropping since I installed ML (and I just now noticed it), or it may have just started a couple weeks ago when I noticed. I'm not sure.
Either way, my MacBook Pro (Mid 2010) now has a battery life of less than an hour, even with extremely light processor load. I contacted Apple about this, and the tech said that the battery was rated for 1000 cycles. I'm currently at 220, and my battery capacity is a pathetic 30%. He said that since I wasn't under warranty, there was nothing they could do besides replace the battery - which I really want to avoid since I'm a broke college student.
Is there anything I can do here? I understand that I'm not under warranty anymore, and this wouldn't be a problem if my battery was degrading normally. However, getting 1/5th of the recommended battery life is pretty sad. I've read that doing a clean install of Mountain Lion/Lion might help. Is there a way I can do this without having to back up all my files? I don't have an external hard drive or anything.
It seems this is a common topic in these forums. Any help or links to solutions would be great. If this is answered in a similar topic, I'll gladly delete.
Here is the system info on my battery, incase that might help:
Battery Information:
Model Information:
Serial Number:          9G030040MD3MA
Manufacturer:          DP
Device Name:          bq20z451
Pack Lot Code:          0
PCB Lot Code:          0
Firmware Version:          201
Hardware Revision:          2
Cell Revision:          158
Charge Information:
Charge Remaining (mAh):          1453
Fully Charged:          No
Charging:          Yes
Full Charge Capacity (mAh):          1939
Health Information:
Cycle Count:          220
Condition:          Service Battery
Battery Installed:          Yes
Amperage (mA):          1507
Voltage (mV):          12214
System Power Settings:
AC Power:
System Sleep Timer (Minutes):          0
Disk Sleep Timer (Minutes):          10
Display Sleep Timer (Minutes):          15
Wake on AC Change:          No
Wake on Clamshell Open:          Yes
Wake on LAN:          Yes
Current Power Source:          Yes
Display Sleep Uses Dim:          Yes
PrioritizeNetworkReachabilityOverSleep:          0
Battery Power:
System Sleep Timer (Minutes):          15
Disk Sleep Timer (Minutes):          10
Display Sleep Timer (Minutes):          10
Wake on AC Change:          No
Wake on Clamshell Open:          Yes
Display Sleep Uses Dim:          Yes
Reduce Brightness:          Yes
Hardware Configuration:
UPS Installed:          No
AC Charger Information:
Connected:          Yes
ID:          0x0100
Wattage (W):          60
Revision:          0x0000
Family:          0x0085
Serial Number:          0x00cb7bc3
Charging:          Yes
Thanks in advance

Condition:
     Service Battery
You need a new battery.

Less than 3 hours WiFi capacity on MacBook Pro Retina 2012 acceptable?

Hi there,
I have my Macbook with 15inch-Retina display since it came out (ordered it the day after it was released) and I am not really satisfied with my battery capacity. According to MagicanPaster (app for system monitoring) I have had 56 charge cycles and the health of the battery is displayed as 97-99% (fluctuating based on load). I am using Lion MacOSX which had those battery problems, but seemed to have them resolved or at least alleviated the problem since some patch a while ago and always keep it up to date as soon as patches are released over the app store. Currently the estimate for battery life is at 50% projecting 1 hour and 22 minutes and I have a CPU load of 12%, WiFi on, Display at 75% brightness, Surfing Safari (no Flashvideo).
So, after all having used this thing for almost half a year I think of returning it to support service because having 3 hours of usual run-time on a battery is really not any different than what I remember from my previous Acer/Dell machines etc. I vaguely remember that back in the years people were proud to tell me that their Mac would last for almost a working day. So really is that all Apple is able to perform?
I remember it was better when I got it, lasting around at least 5 hours until that Lion Update came. Anyone else having similar experience? What about the chances of getting this as manufacturing malfunction under the Apple Protection Plan?
Best,
Citizen

I havent had this problem, but I dont have retina display on my 15 inch MBP. I bought mine right after Mountian Lion was released and didnt do the free upgrade for a while. After upgrading, I didnt see a difference, my mac still runs a "full work day". But i would assume your problem would be covered as "manufacturing malfunction" or something like that because it's not your fault.

How to use the new MacBook 13'' with Built-in 7-hour battery

Hi,
I just bought the new MacBook, it is my first Mac, and having the Built-in 7-hour battery I don't know if I can plug it in most of the times without doing any damage to the battery.
On other portable computers, I just take the battery out and than plug it in and use it, but in this one that can not be done.
So, what to do? Try to always drain and recharge fully, or it is no problem to plug it in when the battery is fully charged?
I read that you should let it sleep(when it goes to sleep because it doesn't have battery)for 5 hours before charging it so it really drains. Is that really necessary?
Also after it goes to sleep and I plug it in to charge, should I let it charge in Sleep Mode, or should I Shut it down and let it charge?
What has been your experience with battery life? The first time I used it, it lasted for 4hours, is this normal and it will get better with 3 or 4 fully charges/draines?
Thank you very much for your help.
Pantuf

Hey guys, I understand your concern that you're not getting 7 hours out of your battery but let me put a couple things into perspective and also offer you some info from Apple's website that may or may not explain why you aren't getting the full 7 hrs.
First mgb545, 5.5 hours is killer for laptop battery, but nonetheless you paid for it for the 7 hour battery so I don't fault you in any way for wanting what they said you would get.
Second, the MacBook is Apple's "sub $1000" notebook. At first mention of that you think, "alright, it's under a thousand bucks!". It is, it's just $999...
My point is that it's an advertising game. The MacBook can get +up to+ 7 hours on a single charge but not everybody is doing the same things or has the same configuration as when Apple was testing their machines. You might have a Time Machine HDD backing up (which I don't recommend nor do I think you guys do since you didn't mention it) or some other USB peripheral that takes power which would lower the battery's life. However, I think there is
This is straight an easier explanation... This next blurb is the "fine print" from Apple's website right on their MacBook page about how they got 7 hrs.
+"Testing conducted by Apple in October 2009 using preproduction 2.26GHz Intel Core 2 Duo-based MacBook units. Battery life depends on configuration and use. See www.apple.com/batteries for more information. The wireless productivity test measures battery life by wirelessly browsing various websites and editing text in a word processing document with display brightness set to 50%."+
That all being said, I think or at least hope you'll find your answer there. For starters, it says "various websites". Who knows if those were basic HTML or Flash heavy sites or a combination of both? The other stipulation of this is brightness. Do you guys have your brightness at 50% or is it higher?
Try this, I know the weekend just passed, but if you find that you have 7 hours where you don't need your laptop, leave it on, make sure it doesn't go to sleep or screen saver, play with it every so often, leave wi-fi on, make sure your brightness is at 50% and then see how long it lasts.
One last thing, when you say you're getting 5.5 hrs out of your battery, how low are you letting it go to? I'm assuming when Apple says "a single charge" they mean it. So if you're getting 5.5hrs when it goes down to 8 or 10% you also need to factor in the extra time you might gain from that.
Hope this help, let me know how your computers are set up, I'm curious to know if this will resolve or at least account for your lack of 7 hrs because me just recently got the 13" MBP and it doesn't get 7hrs either.
-David

Question on amp hour battery capacity measuring

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