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Studying the Slow Decay of a Laptop Battery For an Entire Year

timothy posted about a year ago | from the ashes-to-ashes-dust-to-dust dept.

Power 363

First time accepted submitter jradavenport writes "I've been keeping a log of the health of my MacBook Air battery for the past year, taking samples every minute I use the computer (152,411 readings so far!). This has allowed me to study both my own computing/work habits, but also the fascinating rapid decay of battery capacity. Comparing it to my previous 2009 MacBook Pro, the battery in this 2012 Air is degrading much faster."

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Ah, I see the problem. (5, Funny)

fuzzyfuzzyfungus (1223518) | about a year ago | (#44573651)

You're discharging it wrong, don't do that.

Re:Ah, I see the problem. (0)

Anonymous Coward | about a year ago | (#44573737)

Hey now.. no more making fun of someone who's dead...

Here's the real problem (2, Funny)

Anonymous Coward | about a year ago | (#44573767)

He finds the failure of a product he paid good money for fascinating, rather than infuriating.

Re: Here's the real problem (-1)

Anonymous Coward | about a year ago | (#44574035)

Wonder if that happens with electric car batteries - how much do those cost again?

Re: Here's the real problem (1)

h4rr4r (612664) | about a year ago | (#44574277)

Nothing at first.
They are typically warranted for 10-15 years.

Most people will not own them that long.

Re: Here's the real problem (2)

O('_')O_Bush (1162487) | about a year ago | (#44574361)

Just means depreciation will be worse, and resale value will be lower when the next buyer expects to fork out boatloads for new batteries.

Re: Here's the real problem (1)

h4rr4r (612664) | about a year ago | (#44574383)

$2500 is about what they are, not exactly boatloads.

Most 10-15 year old ICE cars will require extensive maintenance. Go look what a Gen1 Insight with a manual is going for. They seem to retain their value pretty well.

Re:Ah, I see the problem. (1)

Anonymous Coward | about a year ago | (#44573769)

He does refer to "letting the battery cycle" - I though you weren't supposed to do that with modern Li-po batteries.

Re:Ah, I see the problem. (5, Informative)

h4rr4r (612664) | about a year ago | (#44573869)

You have to do that every once in awhile if you want the battery status indicator to be correct. This is because the voltage curve is so flat there really is no other way to determine level of charge other than to count power out and calibrate what the battery should hold periodically.

Re:Ah, I see the problem. (0)

Tukz (664339) | about a year ago | (#44574077)

iWooooosh

Survey says... (5, Insightful)

djupedal (584558) | about a year ago | (#44573685)

Let's see the comparative graph where you did identical tracking over time for both, instead of detailed now against casual before, which seems a bit weak. I'd also like to see how you factor out the constant logging's effect as well.

Re:Survey says... (5, Informative)

BoRegardless (721219) | about a year ago | (#44573831)

We live with what we got now. That is life. But ...

Within a few years that will change with lithium-sulfur batteries if the lab geeks have anything to say about it.

http://www.extremetech.com/extreme/157525-new-sulfur-based-battery-is-safer-cheaper-more-powerful-than-lithium-ion [extremetech.com]

Re:Survey says... (3, Insightful)

Nadaka (224565) | about a year ago | (#44573899)

Yea. a change in methodology between test invalidates the results of an experiment. It could very well be that running the battery test every minute is causing his battery to deteriorate.

Re:Survey says... (3, Interesting)

AmiMoJo (196126) | about a year ago | (#44574029)

While hard data would be nice we can reason that his results are unsurprising.

The older laptop was a more conventional type and thus would almost certainly keep the batteries a bit cooler than the newer, ultrabook style one. Heat accelerates the decline of batteries. I'm not surprised by this result.

PROTIP: Remove your laptop battery if you are running from the mains most of the time and keep it in a cool drawer somewhere.

Re:Survey says... (1)

Anonymous Coward | about a year ago | (#44574285)

Yeah, it's a shame that Apples no longer have removable batteries. In fact, the extensive battery life is advertised as the reason you won't need to remove it.

dom

Re:Survey says... (4, Informative)

aclarke (307017) | about a year ago | (#44574315)

PROTIP: MacBook Air batteries aren't removable (in that sense).

Re:Survey says... (1)

Anonymous Coward | about a year ago | (#44574353)

PROTIP: Remove your laptop battery if you are running from the mains most of the time and keep it in a cool drawer somewhere.

Also discharge the battery to 30%, check it every month or two, and charge back to 30% as necessary. Batteries degrade faster when stored at 100% charge and if left to self discharge too far (below 0%) a safety mechanism will prevent them from charging.

Re:Survey says... (2)

WuphonsReach (684551) | about a year ago | (#44574367)

For devices using Li-Ion, try and adjust your charger settings so that the battery has to drain down to 85-90% (instead of 95-98%) before a charging cycle starts. Fewer charging cycles per year gives you more years out of the battery.

This trick works best if you spend most of your time hooked up to external power. But is still beneficial for devices that get left plugged in for a few days at a time between bouts of heavy use.

Re:Survey says... (1)

pepty (1976012) | about a year ago | (#44574427)

PROTIP: Remove your laptop battery if you are running from the mains most of the time and keep it in a cool drawer somewhere.

YMMV. Most of the heat a removable battery (i.e., designed to be easily removed by the user) experiences occurs due to charging/discharging, since the battery doesn't overlap the hot parts of the motherboard. I never bothered because it is so easy to dislodge the magsafe connector on macbooks.

Re:Survey says... (1)

gpalyu (995482) | about a year ago | (#44574455)

My old MacBook Pro runs at reduced power/speed when the battery is removed. It was not designed to run off the power from a socket alone. Parent isn't necessarily giving good advice.

Laugh (-1, Troll)

koan (80826) | about a year ago | (#44573693)

Bad batteries something Apple is famous for, RAM fixed to the logic board, insecure and buggy OS, and a host of other complaints makes me wonder why anyone pays the premium for Apple any longer.

Re:Laugh (3, Interesting)

Camembert (2891457) | about a year ago | (#44573789)

- Citation please about Apple's batteries being bad? That would mean statistically worse than other brands? - RAM fixed, ok I see your point, on the other hand I think it is the price to pay when building something as slender as a Macbook Air. - insecure and buggy OS: Is it worse than Windows? There are not so many stories about OSX being hacked into. Not saying that it isn't perfect but it seems to work pretty well. Why paying the premium? Yes, I like many of their products (scorn on me here on /.). Very concisely: I am happy how in general it all works substantially well and simply. I even like the painless app store. Of course I will now be dismissed as a poser and a hipster, but really I don't care. I never speak bad about Windows or Linux fans either, each to his own.

Re:Laugh (0)

bobbied (2522392) | about a year ago | (#44574165)

Of course I will now be dismissed as a poser and a hipster, but really I don't care.

Nor do I. You can do whatever you want with your money, including sending it to Apple to purchase their overpriced hardware and buggy software... :)

Seriously, if it works for you, do what you want. I don't hate Apple stuff, I just don't see a good reason to pay that much for it. But I'm a cheap oldie goldie so I end up using 10 year old revamped laptops for work and home. I don't suppose many folks would go to as much trouble, but it's worth it to me.

Re: Laugh (0)

Anonymous Coward | about a year ago | (#44574283)

I worked for them for 4 years and we replaced every battery and case on those white plastic models.

Re:Laugh (4, Funny)

Culture20 (968837) | about a year ago | (#44573863)

Bad batteries something Apple is famous for, RAM fixed to the logic board, insecure and buggy OS, and a host of other complaints makes me wonder why anyone pays the premium for Apple any longer.

Presumably the same reason someone pays big bucks to drink coffee made from coffee beans that have been in a civet's anus. [wikipedia.org]

Re:Laugh (3, Informative)

XxtraLarGe (551297) | about a year ago | (#44573907)

Bad batteries something Apple is famous for, RAM fixed to the logic board, insecure and buggy OS, and a host of other complaints makes me wonder why anyone pays the premium for Apple any longer.

Maybe because that hasn't been most peoples' experience [osxdaily.com] ? I have a MacBook Pro that is almost 3 years old and the battery is still almost as good as the day I bought it. Of course, I make sure to run mine down once a month as recommended.

Re:Laugh (4, Insightful)

Sockatume (732728) | about a year ago | (#44573929)

Apple get the same batteries from the same places everyone else does. They're as fungible as AAs at this point.

Re:Laugh (2)

samkass (174571) | about a year ago | (#44573971)

Bad batteries something Apple is famous for, RAM fixed to the logic board, insecure and buggy OS, and a host of other complaints makes me wonder why anyone pays the premium for Apple any longer.

Your point would be an excellent one if reality wasn't exactly opposite to every statement in your post.

Re:Laugh (0)

Anonymous Coward | about a year ago | (#44573981)

Bad batteries something Apple is famous for, RAM fixed to the logic board, insecure and buggy OS, and a host of other complaints makes me wonder why anyone paid the premium for Apple ever.
...FTFY

Re:Laugh (1)

tlhIngan (30335) | about a year ago | (#44574137)

RAM fixed to the logic board,

A requirement of the form factor. If you check, most ultrabooks in a similar formfactor already solder the RAM on board. You can find ones with removable RAM but they typically are pushing the "Ultrabook" definition because Intel couldn't get anyone to make them otherwise (typically they have hard drives, or 15" screens or are heavier and significantly thicker).

Though, to be honest, I've rarely ever installed additional RAM in any PC I had - given its cost, it's usually cheaper to buy the max up front than in a few years when memory standards change and it's difficult to buy it cheaply (e.g., DDR or DDR2) - especially the larger modules - they either simply stop existing or are still wildly expensive years later.

Re:Laugh (1)

h4rr4r (612664) | about a year ago | (#44574207)

Dell 6430u, actually manages this quite well.
It uses an SSD and a 14" display. Honestly the best Dell I have seen in years as far as build quality goes.

Typically markup on day of sale on RAM upgrades from the OEM are 100%. We always get them with a lower amount of RAM and order more from newegg to have it arrive the same day.

Re: Laugh (0)

Anonymous Coward | about a year ago | (#44574231)

my experience is the exact opposite to yours.

Re:Laugh (1)

notanalien_justgreen (2596219) | about a year ago | (#44574197)

Agreed, I've had 3 different apple laptop batteries - and I've never got more than about a 2.5 hour charge on them, even brand new. I don't know where this bullshit about ~8 hour battery life comes from. I don't even use it that heavily, we're talking about 2.5 hours of internet and Word.

Love my MacBook Air, hate the battery (5, Informative)

geek (5680) | about a year ago | (#44573717)

I got 10 hours of battery life on my 2011 macbook air when I first got it. I don't just mean 10 hours of it sitting idle either. I could get 7 hours of continuous play of movies. Then Mountain Lion came out and I was lucky to get 3 hours tops. That lasted 6 months until they "fixed" it and I was able to get 5 again. Now in I can consistently get 4 hours with it sitting mostly idle.

I love the machine but I hate that I cant change the battery myself. I'll have to pay the Apple tax to get this fixed. I am holding out hope for Mavericks though, hopefully the power saving features can breathe some new life into this thing.

Re:Love my MacBook Air, hate the battery (2)

spamchang (302052) | about a year ago | (#44573877)

Yikes--same format movie played on both laptops = differing battery lives? Definitely sounds like an OS power bug (or several), unless the movie formats differed (lower vs. higher qual). And if not that, the minute possibility remains that someone in the processor architecture team made a tradeoff in the graphics hardware that didn't work as intended.

Going from 7 hrs active to 4 hrs idle is depressing :(

Re:Love my MacBook Air, hate the battery (1)

Sockatume (732728) | about a year ago | (#44573915)

Did they change anything in the graphics drivers with the OS update? I wonder if maybe hardware acceleration on video either got knocked offline or became really inefficient.

Re:Love my MacBook Air, hate the battery (5, Insightful)

samkass (174571) | about a year ago | (#44574021)

I love the machine but I hate that I cant change the battery myself. I'll have to pay the Apple tax to get this fixed. I am holding out hope for Mavericks though, hopefully the power saving features can breathe some new life into this thing.

If you are willing to unscrew two dozen little screws, the battery swap-out is actually pretty easy according to iFixit. Of course, the battery itself will cost you over $100 bucks new, and Apple only charges about $120 installed, so the only real reason to do it yourself is if you live far away from an Apple Store and don't trust a carrier service with your laptop.

Re:Love my MacBook Air, hate the battery (2, Insightful)

geek (5680) | about a year ago | (#44574293)

Yeah, I dont want to void my warranty either.

Re:Love my MacBook Air, hate the battery (2, Funny)

h4rr4r (612664) | about a year ago | (#44574419)

You don't want to void a warranty and you call yourself a geek?

How much did you pay for that UID on ebay?

Warranty will be expired by the time most batteries will be needing replaced.

Re:Love my MacBook Air, hate the battery (0)

Anonymous Coward | about a year ago | (#44574055)

The battery swap is cheap at Apple. Cheaper than most people charge for the easily replaceable spare batteries.

Re:Love my MacBook Air, hate the battery (3, Insightful)

tlhIngan (30335) | about a year ago | (#44574059)

I love the machine but I hate that I cant change the battery myself.

Yes you can, and it's not that hard [slashdot.org] .

You know what the hardest part of it is? Going to ifixit, getting the screwdriver, and clicking "checkout now".

8 screws for the bottom cover, and 3 more securing the battery to the case. OK I take it back, the hardest part is possibly removing the bottom cover - Apple does use rather strong clips.

The same is true for everything OTHER than the MacBook Pro Retina 15", which has annoyingly-glued in batteries. I think the 13" is on a carrier frame.

It definitely isn't rocket surgery.

Re:Love my MacBook Air, hate the battery (1)

Gibgezr (2025238) | about a year ago | (#44574265)

This seems like a lot of work. I like laptops that allow me to push a switch and drop out the battery and swap in the spare in about 5 seconds...which would be almost every other laptop in the world other than ones made by Apple?

Re:Love my MacBook Air, hate the battery (1)

geek (5680) | about a year ago | (#44574317)

But it'll void my warranty which isn't cool and why bother with all that when its only an extra 20 bucks to have the genius bar do it for me?

Besides, the point was that I can't swap it with another one part way through the day like I can with my work HP laptop. I can't even dole out extra bucks to buy an extended battery. I have two for my HP, one that lasts about 3-4 hours and another that will get me about 7-8. I just slap it on and away I go.

Haven't been able to do that with an Apple in years, not since the MacBook Pro's had it in 2009 I think.

Re:Love my MacBook Air, hate the battery (3, Informative)

Bogtha (906264) | about a year ago | (#44574079)

If your battery was great until a software update, then the problem probably isn't the battery but the software, and replacing the battery won't solve your problem.

I really enjoyed this article (1)

MetalliQaZ (539913) | about a year ago | (#44573719)

I seem to be constantly fighting the battle with battery life, and it is a topic that I am acutely worried about, thanks to the newest generation of phones which seem to have settled on non-replaceable batteries. I found this very interesting. Glad someone took the time to take these measurements and write it up.

non-replaceable batteries (1)

nurb432 (527695) | about a year ago | (#44573855)

They are considered disposable and if you can make it until the next upgrade cycle/treadmill they don't care.

For those of us who actually buy our phone outright, it sucks.

Re:non-replaceable batteries (1)

h4rr4r (612664) | about a year ago | (#44573923)

What do you mean non-replaceable?

Do you not know how to work a screwdriver?
Lefty loosy, righty tighty. You can order the battery and driver online if the latter is an oddball shape.

Re:non-replaceable batteries (1)

MetalliQaZ (539913) | about a year ago | (#44574251)

With voided warranty.
And that's assuming you can find the replacement parts for your model, which isn't straightforward for anything other than iphones.

Re:non-replaceable batteries (1)

h4rr4r (612664) | about a year ago | (#44574445)

If it was under warranty you could have them do the work for free. So which is it? You are under warranty and don't need to worry or you are not and voiding it does not matter?

Bullshit, I have found parts for many smartphones, including screens and power ports. No different than getting ebay laptop parts.

Two Things (0)

JeanCroix (99825) | about a year ago | (#44573721)

1) It's "without further ado," not adieu.

2) Is it possible that querying the battery health once per minute actually invokes some mechanism which causes it to degrade at a higher rate?

Re:Two Things (2)

erikkemperman (252014) | about a year ago | (#44573763)

Ha, I actually stopped reading at "Without further adieu". But that says more about me than the author, I suppose...

Re:Two Things (2)

JeanCroix (99825) | about a year ago | (#44573801)

I almost stopped there, but I admit to proceeding because I was looking for more grammatical mistakes. Oh, and I was interested in the battery life too.

Re:Two Things (2)

Aguazul2 (2591049) | about a year ago | (#44573847)

Ha, I actually stopped reading at "Without further adieu". But that says more about me than the author, I suppose...

Maybe it is the unconscious suggestion that he had finished what he was saying? An unconscious Alt-F4 -- the adieu button.

Re:Two Things (2)

erikkemperman (252014) | about a year ago | (#44574429)

Alt-F4... Give me a little credit, will ya? I'm running Mint on my MBP, you insensitive clod!

Re:Two Things (1)

Bomarc (306716) | about a year ago | (#44573901)

If you stopped reading at ... "adieu" -- then technically - he got it right. Other than it might have read "with all the adieu" ... ?

Re:Two Things (5, Funny)

Culture20 (968837) | about a year ago | (#44573821)

1) It's "without further ado," not adieu.

You're making much adieu about nothing.

Cockadieudledoo!

Re:Two Things (2, Insightful)

jradavenport (3020071) | about a year ago | (#44573839)

1) Oh shit, you're absolutely right. I'm a bit anal about such things as well, changing it now!! 2) I'd wondered that too, that by measuring it i'm actually causing changes. I'd love to conduct a larger study to control for such things.

Re:Two Things (2)

Sockatume (732728) | about a year ago | (#44573883)

I don't think so. State-of-health measurement can be a subtle art but it all comes down to measuring the cell's voltage and resistance over time*, which at the end of the day you're getting for free when the battery is in use.

*Looking for voltage sag, rising internal resistance, or simply less area under the curve.

Re:Two Things (1)

JeanCroix (99825) | about a year ago | (#44573959)

Most likely, but it's still something that should be checked definitively. In going from once a week to once a minute, you're increasing the sample rate by a factor of over 10,000. Even tiny effects could become magnified.

Re:Two Things (2)

Sockatume (732728) | about a year ago | (#44574009)

I guess what I'm saying is that there shouldn't be anything changing from the battery's perspective; the "multimeter" is always plugged in, as long as the computer's on. Unless the battery testing itself was driving up the power demands from the laptop, and thus drawing more current from the battery, it shouldn't make a difference.

Re:Two Things (1)

JeanCroix (99825) | about a year ago | (#44574091)

Exactly. That latter part is what should be ruled out. I agree it shouldn't. But what if it does?

Re:Two Things (3, Informative)

JeanCroix (99825) | about a year ago | (#44574439)

I was thinking about it more during lunch. It's not just a battery test which occurs every minute, it's the entire script he wrote, including the testing and the subsequent appending of that data to a file. That could amount to a significant number of drive accesses which normally wouldn't have happened, especially at night when it would have otherwise been idle.

brush more often (1)

Anonymous Coward | about a year ago | (#44573727)

you should have brushed it at least twice a day.

Treat laptop batteries as risky UPS. (1)

Culture20 (968837) | about a year ago | (#44573779)

Nice to have if the power goes out unexpectedly, but shut down ASAP.

Re:Treat laptop batteries as risky UPS. (1)

SleazyRidr (1563649) | about a year ago | (#44574041)

That's not really the point of a laptop battery. Also, doesn't leaving it plugged in all the time kill the battery faster than anything?

Re:Treat laptop batteries as risky UPS. (1)

WuphonsReach (684551) | about a year ago | (#44574397)

For a few reasons:

#1 is because most (all?) Li-Ion batteries can only be charged a few hundred times. Even a partial charge from 95% back up to 100% can count as a "charge cycle". So one tactic is to change your power management settings so that it doesn't start a charge cycle until the battery hits 80-90% levels.

#2 is heat.

Power storage that doesn't degrade... (0)

Anonymous Coward | about a year ago | (#44573795)

Why aren't we filling our laptops, tablets and phones with compressed H2 that we make in our own homes with our new appliances (electrolyzers) that take distilled water? Why isn't this happening yet! Storage that does *not* degrade. The power density isn't great enough for cars but is awesome for portable electronics.

Duh...

Re:Power storage that doesn't degrade... (4, Informative)

h4rr4r (612664) | about a year ago | (#44573965)

Because of the whole host of other problems with that suggestion.
Here is a small set of them, there are many more
1. expensive fuel cell
2. low density storage unless you go with expensive metal hydrides
3. H2 embrittles everything
4. far cheaper to make H2 via steam reformation of natural gas than electrolysis

Re:Power storage that doesn't degrade... (0)

Anonymous Coward | about a year ago | (#44574431)

And you don't think batteries are inefficient? As hot as they get when charging and when using? Keeping the voltage as close to 2.5V across each electrolyzer cell when performing electrolysis of water with a PEM membrane is pretty efficient. The PEM fuel cell, however, is not as efficient (I know it's basically the same device used in reverse).
Portable electronics don't use much energy so a tiny cylinder with compressed H2 can last long enough.
The fuel cell IS expensive and would drive up the cost a bit.

The other thing I thought of is, unless you store oxygen too, what happens if you have a fuel cell phone in your pocket for a long time? lol, do you need a snorkel? Storing the oxygen too wouldn't be practical. The other big challenge would be using this technology in tiny/thin cellphones. Laptops and tablets wouldn't be as hard.

You'd be surprised how much energy you can get from a tiny cartridge of hydrogen stored at 100 to 150 PSI. I play around with fuel cell technology all the time. Also, I have a 1200 cc/min PEM-based hydrogen generator.

How do you think monitoring works? (1)

damn_registrars (1103043) | about a year ago | (#44573803)

Your software is querying the battery, which in turn takes battery power. If you keep asking it to check on itself every minute, you are decreasing its life expectancy in so doing. While it wouldn't produce as rich of a data set, if you really want to know how long your battery lasts at idle, you need to track it with pen and paper.

Re:How do you think monitoring works? (0)

Anonymous Coward | about a year ago | (#44573873)

Pay no attention to the man behind the curtain! Apple is flawless, its you who is the problem!

Is it really? (1)

Anonymous Coward | about a year ago | (#44573823)

So far as I can tell, you're looking at the reported capacity from the intelligent charging circuitry. From my experience, and the reports I've heard, this has only a tenuous connection to reality.

From what I can see, the author has not actually ever measured the unit's battery life.

Power States (1)

MMerc (684605) | about a year ago | (#44573837)

What the study shows is that logging the battery life every 1 minute prevents the laptop from staying in a low power state for long periods of time. This is like flipping your house lights on and off every 1 minute for a whole year and wondering why your power bill is rising through the roof.

Letting the battery cycle? (3, Informative)

spamchang (302052) | about a year ago | (#44573845)

Most modern lithium batteries should *not* be cycled or discharged "fully"--such a practice degrades the battery capacity quite rapidly. I think the practice of fully discharging the battery comes from the NiMH-type rechargeable AA(A) batteries.

Yeah, sometimes people recommend fully discharging a lithium battery during operation so that the monitoring software can recalibrate it's battery power meter to adjust for the decline in total capacity, but I'm not sure it's worth it.

As mentioned earlier, temperature is a big factor as well. Maybe Haswell will save the day...

Re:Letting the battery cycle? (1)

Sockatume (732728) | about a year ago | (#44573903)

No modern li-ion battery will let you charge or discharge it far enough to cause actual damage. You can treat them however you like cycle-wise and you'll get about the same total lifespan out of them. Using the battery and how long has passed since manufacture are by far the limiting factors.

Re:Letting the battery cycle? (0)

Anonymous Coward | about a year ago | (#44574087)

I think the practice of fully discharging the battery comes from the NiMH-type rechargeable AA(A) batteries.

It predates those bit, back in the '80 when we used NiCad batteries they told us to completely discharge them then fully recharge them so they wouldn't develop a "memory" problem.

No modern li-ion battery will let you charge or discharge it far enough to cause actual damage.

You're assuming some charge monitoring/protection circuits are in the battery. That may be the case in laptops (not sure), but with simple Li-ion batteries used for something like radio controlled cars and planes there is a serious risk if you aren't using the correct smart charger for the battery.

Re:Letting the battery cycle? (1)

PPH (736903) | about a year ago | (#44574111)

No modern li-ion battery will let you charge or discharge it far enough to cause actual damage.

Tell that to Boeing.

Re:Letting the battery cycle? (0)

Anonymous Coward | about a year ago | (#44574127)

No modern li-ion battery will let you charge or discharge it far enough to cause actual damage. You can treat them however you like cycle-wise and you'll get about the same total lifespan out of them. Using the battery and how long has passed since manufacture are by far the limiting factors.

Rubbish. Yes the control electronics place some restrictions on what you can do to prevent catastrophic failure, they do nothing to prevent increased wear and tear on the battery. For example if you never let the battery dishcharge below 50%, it will last for more than double the number of discharge cycles. If you never charge it above 90% capacity this will also increase the life of the battery. Similarly with storing it in lower temperatures.

So some general tips for Li-ion batteries:
Never discharge them more than you need to, if there is a charger nearby, plug in your phone/laptop regardless of the charge level.
If you know you're not going to be long without a charger and won't be doing much with your device, only charge it to 80-90%.
When storing/not using the battery for long periods, store it somewhere cold, the fridge if possible.
When playing games or anything that requires lots of power, plug your device in if possible. High current draw from the battery heats it up (as well as the heat from the CPU etc) and sustained high temperatures will shorten the battery's life.

Source: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Sampling frenzy (0)

Anonymous Coward | about a year ago | (#44573857)

Maybe polling the battery every minute reduces battery life?

Re:Sampling frenzy (1)

jones_supa (887896) | about a year ago | (#44574459)

I don't know... In Linux if you turn on ACPI debugging, you can see that ACPI spouts constantly (maybe twice a minute or something like that) an event from the battery (CMB1 or other name). Maybe when you "poll" the battery, you simply get the most recent values that the ACPI driver stored from the latest report?

Then replace the... oh thats right (0)

Anonymous Coward | about a year ago | (#44573879)

You should replace the battery or have a spare waiting.

Oh, that's right. Apple doesn't allow you to do that. They expect you to upgrade to the new model every year and everyone obeys gladly.

Re:Then replace the... oh thats right (1)

h4rr4r (612664) | about a year ago | (#44574001)

Re:Then replace the... oh thats right (1)

PPH (736903) | about a year ago | (#44574185)

Not something one can do when your battery gets low and you want to swap it out sitting in a coffee shop.

In my opinion, to be user replaceable, there should be no tools required (perhaps a latch one can turn with a dime would be OK). Certainly not a proprietary Apple 5 point driver bit.

Perfectly valid (4, Informative)

Russ1642 (1087959) | about a year ago | (#44573997)

I love studies with a sample size of one. No statistics, no variability. Definitive.

Re:Perfectly valid (2)

geek (5680) | about a year ago | (#44574065)

Its not a study. It's just someone monitoring their own laptops battery life. Lighten up.

Re:Perfectly valid (3, Insightful)

Russ1642 (1087959) | about a year ago | (#44574413)

But he published it, and then Slashdot picked it up, and people are actually interpreting the 'data' and making conclusions. This is how crap like thimerisol=autism gets out there.

Re:Perfectly valid (1)

dotancohen (1015143) | about a year ago | (#44574443)

Its not a study. It's just someone monitoring their own laptops battery life. Lighten up.

Then why is it being reported on at a news website?

Re:Perfectly valid (0)

Anonymous Coward | about a year ago | (#44574073)

You are free not to read it. This guy spent time putting the numbers together, and did not put it out as a double blind research study. If you want to compare it to your own results, you are also free to. You are also free to make snarky comments as you just did.

Re:Perfectly valid (4, Insightful)

Sockatume (732728) | about a year ago | (#44574121)

Yes, because the author insisted that it was the definitive study on how all Macbook batteries behave, so we've got to hold him to that standard. I'll go further: this cad didn't even have this published in Physical Review Letters, much less Science or Nature. He didn't even get it peer reviewed, and... my God, there's no conflict of interest statement! Who was his ethics board?!

Sweet Jesus, I'll bet he isn't even working in a laboratory!

Re:Perfectly valid (1)

Twinbee (767046) | about a year ago | (#44574363)

It may encourage a more definitive study, especially if many others have reported similarly bad battery life for the air.

Re:Perfectly valid (1)

Anonymous Coward | about a year ago | (#44574387)

Summon the Apple haters to pile on!

every apple product (1, Informative)

slashmydots (2189826) | about a year ago | (#44574037)

Almost every iPhone on record has been more likely to shatter its screen than the one before it. Apple went from 1st in lowest malfunction rates to 6th from 2007 to 2011. The new ipad is heavier, runs hotter, and gets worse battery life than the one before it. This isn't exactly a new pattern that the battery in the new air is inferior. Everything Apple is going downhill.

Re:every apple product (1)

h4rr4r (612664) | about a year ago | (#44574085)

That is because each one is more scratch resistant.
Android phones are the same, I only own those actually. The harder the glass gets the more brittle iy is.

Their malfunction rate went up with volume, not really surprising. I hate to be defending Apple, but you are being rather unfair.

Siiiiigh, the SMC provides an ESTIMATE (4, Insightful)

SuperBanana (662181) | about a year ago | (#44574063)

Calculated battery capacity is an estimate, nothing more, used by power management to decide when the computer should be force-slept, then suspended to disk to keep from damaging the battery (ie, it's not useful to wake up too late from sleep to do the suspend-to-disk.)

The SMC's estimate is just that: an estimate. Errors build up over time, and certain things fake it out a bit. For example, note the capacity, unplug the laptop, use it for 30 minutes, plug it in. Immediately the value will be different. It'll change again when fully charged. Your battery capacity didn't actually change. Even in a perfect world, since batteries have internal resistance, capacity gauges can never be perfect(if you draw at X you'll get less power out than if you draw out at X*0.8), and the battery's capacity varies with temperature. Battery degradation is impacted by temperature as well, so unless you're controlling for temperature of the pack, this was a completely useless endeavor. The only way this would have been useful would've been to cycle several (probably a dozen or more) batteries on lab-grade equipment in a temperature-controlled environment.

The noise and big upward swings alone should tell you that using the SMC's estimate for the purposes of statistical analysis or trending is virtually useless.

The stupid shit I see "enthusiasts" of any product obsess over is absurd. The time wasted on such an exercise far outweighs the impact it possibly could have had on the author (and probably even 9-10 other people combined.) The batteries last for well over 6 hours. Most people using a ultrabook with the battery life of a Macbook Air have plenty of opportunities to charge their machines during the course of a day.

Re:Siiiiigh, the SMC provides an ESTIMATE (0)

Anonymous Coward | about a year ago | (#44574451)

My macbook pro is less than 8 months old and it does NOT last for 6 hours. I'm lucky to get 3 hours.

Um, er, about that "battery capacity" (0)

Anonymous Coward | about a year ago | (#44574083)

I'm afraid you've been conned by several digital phantoms.

(1) There is no way to actually know the remaining charge in a battery. The little microprocessor in the battery or the laptop can take a good guess, by integrating the current draw over time, it can measure how many watt-hours have been drawn out, and from integrating how much charge has gone into the battery, and how the battery temperature went up, which signals that it's fully charged (or dying due to high ESR), and from previous discharge cycles, it can roughly compute what the battery capacity used to be, very roughly, but only if you discharged it until the voltage was significantly drooping. And so then the microprocessor can very roughly tell you that there is xx% of charge remaining. Very roughly. Very roughly.

(2) You probably did not measure the laptop's current draw over time. Perhaps you've been using the CPU more intensively, or you're using apps or web sites that need more processing power. Watching video or playing video games use a whole lot more power than light web site browsing. The Macbook air takes very aggressive steps to minimize power draw, that's good, but that also makes for a big jump when you go from light-duty to heavier-duty power-hungry apps.

(3) You are just one data point. And people with bad experiences tend to stand out, so we really can't generalize from your possibly bad experience to anything more general.

While your conclusion might be true, there are also all those other confounding factors that cast substantial doubt.

Continuous charging kills batteries (1)

mybecq (131456) | about a year ago | (#44574179)

My laptop is rarely off AC power. When I had the charger set to stop charging at 100% (and to recharge when 90%), my battery life greatly improved. OId battery dropped 60% in reported capacity in less than 2 yrs; new battery is barely down 30% in the following 4 years.

I call it Chinese electron torture for your battery -- drip, drip, drip.

I don't know how OS X controls battery charging, but all OS's should provide an option to stop charging at 100%.

just use car battery (0)

Anonymous Coward | about a year ago | (#44574301)

o wait my car is built on laptop batteries
Tesla Powered

Cycle count is meaningless (1)

bored (40072) | about a year ago | (#44574369)

Without knowing how deep the cycle was. Furthermore, the rate of discharge and temperature during the discharge will also have a fairly significant affect.

Basically, you will get about 1/10th the charge cycles out of a battery that is nearly completely discharged vs one that is only discharged to 10%.

Its better to really think of LI as providing a fixed number of watt hours. You can consume them in small bites, or you can consume them in big chunks but once you consume them they are gone.

The best rule for laptops is carry the charger and use it when at all possible.

Oh, and don't buy machines without replaceable batteries. If the "average" user can get 3 years out of it, and you decide your going to use all 8 hours of battery life every day, and charge it at night, you will probably be lucky if it lasts a year.

Plus, if your laptop gets hot (either by being left somewhere hot, or because of poor cooling) then the battery life is going to nose dive even if your plugged in. If your going to be doing a lot of intense gaming, your probably better taking the battery off and placing it somewhere cool (just don't let it discharge).

See this link http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries [batteryuniversity.com]

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