
The De-evolution of My Laptop Battery - brendan_gill
http://www.ifweassume.com/2013/08/the-de-evolution-of-my-laptop-battery.html?bg
======
JimmaDaRustla
WHOA!!

Huge mistake here - he says he cycles his battery! DO NOT DO THIS TO LITHIUM
ION BATTERIES! Lithium Ion will last longer by NOT allowing the cells to be
fully discharged!

This is the opposite of Nickel Metal Hydride and Nickel Cadmium - these types
of batteries DO require a full discharge and full recharge in order to provide
a longer life.

In addition, the number of discharges, the temperature, etc all come into play
with lithium ion. These thinner laptops are actually lithium ion polymer,
where the materials are folded into packs...much more susceptible to the
elements, like heat.

Disclaimer: Spent 3 years in the battery field.
[http://batteryuniversity.com/learn/article/how_to_prolong_li...](http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries)

Edit: Just want to point out that charging a laptop while using it could
potentially create more heat, degrading the battery. I'm not sure what is more
damaging - letting the li-ion battery drop below 70%, or charge it while the
laptop is being used. So many variables!

~~~
mistercow
The really dumb thing is that, as far as I can tell, a battery's controller
generally counts a "cycle" as "started discharging, started charging",
regardless of time in between. At least, that's how it was with my MacBook a
few years ago. Unplug, plug in, cycle count increases.

The crappy thing about that is warranties. Apple, for example (at least last I
checked; I don't use a Mac anymore) , would replace a battery if it had under
some number of charge cycles (and presumably was less than a year old), but
not if it had more than that number.

That means that if you treat your battery really nicely by always keeping its
charge between 40% and 60%, and it turns out to be defective, they probably
won't replace it because of how many "cycles" it has gone through.

Of course, those kinds of cycles have very little to do with the longevity of
a Li+ or LiPo battery anyway. A better metric would be total energy output
over time, which would be far simpler to calculate anyway.

~~~
hedgehog
I don't believe that description of cycle count has ever been accurate for
Apple hardware and certainly isn't for recent MacBook Airs:

[http://support.apple.com/kb/HT1519](http://support.apple.com/kb/HT1519)

~~~
hobs
Yeah it definitely doesnt, I have had and used dozens of macbooks and you cant
ever plug in and out and see your charge cycle increase each time. I usually
have my laptops 1-2 years and they rarely go above 300 charge cycles per year,
and I usually dc my laptop 5-10 times a day.

------
YooLi
If your cycle count is 223 and you are nearing 80%, then your battery is
defective, plain and simple. Apple will replace it. It's happened to me a
couple times and Apple took care of it with no hassles.

~~~
cliveowen
I can attest to that: my Macbook white bought on October 2009 (that's 46
months folks) which I used every single day to this very day has 261 load
cycles and 91% of original capacity.

~~~
to3m
That's pretty good going I would have thought? As well as charging cycles, I
assume time is a factor. My Macbook Pro (bought July 2009) had reached 65%
capacity by the time I replaced it, after something like 45 months and ~250
cycles. By then the computer had been begging me to replace it for about six
months.

I actually thought this perfectly reasonable, with nearly 4 years being a fair
lifespan for a battery, no matter how few cycles it might have been through.
While it was obviously knackered, it still held enough charge to be perfectly
useful, if not amazing - but perhaps I should have held it to a higher
standard?

(Hopefully it's just this year's unusually hot UK summer but after a mere ten
cycles its replacement is down to 93% already. So maybe there's just something
up with the electricity supply to my flat.)

------
nakedrobot2
Wow, this is an excellent article! Nice visualization of the battery life.

I am quite nervous about the battery sealed inside my own new Macbook. Is it
better to attempt to use the battery as much as possible in order to get a new
one before the 3 year Applecare Warranty expires? Or to maniacally keep the
machine plugged in if at all possible? Or simply not to care? The price of a
replacement will be high, and I wonder how many years it will even be possible
to replace these batteries.

The thinness of my laptop is amazing, but I would rather have a battery that
is not GLUED inside the machine.

~~~
glhaynes
I believe Apple charges $199 for a battery replacement, which is definitely
not cheap, but might be worth it if you were still happy with the rest of the
machine. I'm not sure how long it takes them to do it, though. I'd expect
they'd continue to offer that service for quite a few years to come.

As other posters have mentioned, it seems to me like the glued-in batteries
don't rapidly decline like the old ones did. I don't have any numbers, though,
just impressions.

~~~
gz5
imo very conscious decision on part of Apple (and PC makers) to provide short
battery half lives, rather than spending more money to deal with the size and
heat/cooling constraints of laptops, especially the thin lightweight variety.

not only saves them money short term, but helps push users to new versions
before they really need to jump...

~~~
glhaynes
Is there evidence for this? Is there a better battery tech the entire industry
should be using instead? Seems unlikely.

~~~
another
Not to support the "evil executives" hypothesis---obvious market(ing) forces
are a sufficient explanation for the dominance of LiCoO2---but I would easily
opt for a laptop that offered an LiFePO4 ("iron phosphate" [0]) option. The
drawback would be slightly reduced initial capacity; the advantage would be
much greater cycle life. Also, less spontaneous combustion.

[0]
[http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery](http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery)

------
D9u
Not an Apple consumer here, but my netbook battery only lasted about one year,
and I attribute this rapid failure to my use of a cheap, (I live off-grid)
modified sine wave, voltage inverter, but I have no valid proof of my
assumption. As likely a cause for the battery failing to take a charge is the
fact that I often ran the netbook until the battery charge depleted to the
point of shutting the PC down.

When I bought my current, pure sine, inverter I noticed that my new battery
lasted nearly twice as long, but since switching to FreeBSD last year my
second battery quickly bit the dust...

I'm expecting the present battery to last somewhere between one and two years,
but I'm not taking that expectation to the bank.

~~~
Sheepshow
To confirm or disprove your idea, you could look at the output of the battery
charger rather than the input to it.

In general, AC-DC converters are pretty insensitive to the harmonic content of
the AC input because their role is to remove any harmonic content they do
find. They do this with huge low-pass filters with corner frequencies well
under 1Hz, whether the charger is either linear (unlikely) or switching (much
more likely).

When AC becomes distorted, you start seeing harmonics (i.e. contributions at
higher frequencies). Low pass filters are progressively more effective at
higher frequencies. This is to say, I wouldn't be at all surprised if the
efficiency of the charger itself suffered, but the output voltage was
unaffected, meaning the laptop was unaffected.

~~~
D9u
Interesting, but does using a DC to AC inverter change anything?

I've noticed that cell phone batteries also failed prematurely when I had the
modified sine inverter.

Do you mean that if my charger was operating with less efficiency due to
modified sine wave input then my batteries were not likely to be affected?

~~~
XorNot
It's more likely that you were simply cycling the batteries more aggressively
due to the circumstances which led to you using a DC-AC inverter.

------
voidlogic
>letting the battery cycle*

Wait- I thought that was for NiCd batteries and Li-ion batteries where suppose
to always be topped off? Furthermore going below 15-20% charge hurts their max
charge level?

*By cycle he means running it down and charging it up?

~~~
Arjuna
The official advice is:

"Apple does not recommend leaving your portable plugged in all the time. An
ideal use would be a commuter who uses her notebook on the train, then plugs
it in at the office to charge. This keeps the battery juices flowing. If on
the other hand, you use a desktop computer at work, and save a notebook for
infrequent travel, Apple recommends charging and discharging its battery at
least once per month.

[...]

If you don't plan on using your notebook for more than six months, Apple
recommends that you store the battery with a 50% charge." [1]

[1]
[http://www.apple.com/batteries/notebooks.html](http://www.apple.com/batteries/notebooks.html)

~~~
wikwocket
I wonder if using your laptop plugged in at your desk 90% of the time, but
carrying it around to use in meetings the other 10%, is as good as their
"ideal use."

~~~
theGimp
Maximizing your battery's life is not remotely close to a science, but as a
rule of thumb, discharge to 50% every couple of days then recharge.

~~~
wikwocket
Well as long as there continue to be long, drawn-out, rambling meetings, we're
good to go! Although in that case, a short battery life is a feature: "Oops,
I'm at 5%! Be right back while I fetch my charger!"

------
uptown
I've only recently started collecting data for my Early 2011 MBP, but I'm
starting to see a pretty steep decline. From 72% capacity down to 58% in a
little over a month feels like I might be nearing the end of life for my
battery.

    
    
      date       | capacity   | loadcycles
      ------------------------------------
      2013-07-08 | 4964 (72%) | 527
      2013-07-25 | 4566 (66%) | 534
      2013-08-05 | 4432 (64%) | 537
      2013-08-16 | 4016 (58%) | 542
    

Anyone have any advice to stretch its life longer, or is this pretty typical?

~~~
ballard
mid 2010 5020/5770 (87%) and 393. I'll have to starting track this also.

------
Silhouette
Interesting experiment, but watch out for the vertical scale on the charts
showing capacity against time.

~~~
saidajigumi
Yeah, not pegging the axes at zero makes for a _much_ more dramatic graph -- a
classic way to lie with data viz. Sometimes it's fine to do that (e.g. because
without scaling it's impossible to visually understand some of the data), but
the context should be made clear.

That said, the plot of the Macbook Air's battery performance vs. the Macbook
Pro's is really interesting. I haven't done the tracking, but this agrees with
my anecdotal sense is that my 2011 MBP (likewise a main work+personal system)
has had really excellent battery longevity relative to prior Mac/other laptops
I've used.

------
outworlder
As far as I understand, there are two major factors that will shorten the
battery life considerably.

One is heat. This may not be avoidable depending on the computer usage. My mom
"plays" Second Life (for english lessons) and her battery barely lasted two
years - expanding to the point that the trackpad on her Macbook Pro was
sticking out.

Another is leaving the computer plugged in all the time, which will top the
battery - and apparently lithium batteries hate that.

Some electric cars have the option to only recharge the battery up to 80%, to
increase the lifespan. Would it be possible to do the same with laptop
batteries? Perhaps by patching the SMC?

~~~
GuiA
>Another is leaving the computer plugged in all the time, which will top the
battery - and apparently lithium batteries hate that.

I thought modern batteries had mechanisms in place to prevent that?

~~~
outworlder
I'd think that they will actually recharge to somewhat less than 100%. But
Apple still recommends unplugging the computer from time to time, so I'm
assuming they get to very near full capacity.

My laptop is plugged in to a Thunderbolt Display almost all the time, so the
battery gets topped off. It says that it is "charged", but I have no idea how
much absolute capacity is that.

If I'm not going to unplug the notebook anytime soon (not travelling, not
weekend), then I should be able to tell to leave it half charged (half, since
discharging completely is even worse).

------
rsynnott
One other possibility; does the "battery health" metric actually mean the same
thing it did four years ago? My 2012 MBA is showing 92% capacity, and seems to
last about as long as it did when new. My 2007 MBP shows ~70% capacity, and
lasts about an hour; it lasted about four hours when new. I'm not convinced
it's that meaningful a metric.

------
post_break
I have 378 cycles, 90% capacity. Original capacity, 4680mAh, current capacity
4228mAh. Same laptop as him. Mac is 18 months old. His must be flawed.

------
tokenadult
This discussion is very interesting. I'm puzzled about how to keep batteries
working longer, so I looked around for some sources,

[http://batteryuniversity.com/learn/article/how_to_prolong_li...](http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries)

[http://lifehacker.com/5875162/how-often-should-i-charge-
my-g...](http://lifehacker.com/5875162/how-often-should-i-charge-my-gadgets-
battery-to-prolong-its-lifespan)

[http://www.latimes.com/business/technology/la-fi-tn-five-
fre...](http://www.latimes.com/business/technology/la-fi-tn-five-free-
smartphone-battery-apps-20130809,0,2552192.story)

[http://gigaom.com/2013/06/06/new-ti-chips-speed-charge-
times...](http://gigaom.com/2013/06/06/new-ti-chips-speed-charge-times-and-
extend-battery-life-for-smartphones-tablets/)

with background information about batteries. It would be great to hear
comments about what these sources say. I need a reality check on how to take
better care of batteries in rechargeable devices.

------
ahoge
[http://en.wikipedia.org/wiki/Lithium-
ion_battery#Battery_lif...](http://en.wikipedia.org/wiki/Lithium-
ion_battery#Battery_life)

> _The rate of degradation of lithium-ion batteries is strongly temperature-
> dependent; they degrade much faster if stored or used at higher
> temperatures._

That might be related. MacBook Airs get _really_ hot even if you aren't doing
anything too taxing.

------
mikegrb
So, this inspired me to collect similar data on my laptop. I'm collecting a
few more data points, internal battery temp, individual cell voltage, etc. I'm
estimating 30-60 MB/year at 1 minute intervals. My script is available on
GitHub here [https://github.com/mikegrb/Battery-
Logger](https://github.com/mikegrb/Battery-Logger)

------
enscr
I've set my thinkpad to 'start charging' when below 40% & 'stop charging' when
it reaches 60%. I use it with AC power plugged in while the battery floats
~40-60% charge level. Once a month I power cycle it to re-calibrate the
battery. It's been going good for the past 3 years. Shows 500 cycle count with
80-90 hrs/week usage & ~80% capacity.

------
aroman
I have exactly the same laptop, purchased from an Apple store ~14 months ago.

I have more than double his cycle count at 569. My battery is at 85% capacity.

I'd say your battery is defective, or you were doing something to it that
caused it to degrade more rapidly.

It's also a little unnerving that the 2009 MBP has an apparently far superior
battery, despite Apple's explicit claims to the contrary.

------
jlgaddis
My laptops (two-year-old MacBookPro and three-month-old Thinkpad W530) are
plugged in probably 90% of the time I'm using them (8+ hours per day).

From reading some of the other comments here, it sounds like I shouldn't use
them while they're plugged in. When they're being used 8-12 hours per day,
however, it's impossible to avoid.

------
nwh
My 2011 MacBook Pro is doing a lot better than my 2007 one. With similar use,
the older MacBook went through about a battery every year and a half,
replacing once they could only hold up an hour or so of charge. I'm up to 750
cycles and holding high at 98% "health".

The OPs MacBook air sounds defective, or at least, under-performing.

------
sengstrom
How do you even measure max capacity of the battery? Is it by keeping track of
the current balance or is there some other direct physical way to do it?

Measuring once per minute seems like massive overkill for a property that
changes on a timescale of months, but the interesting question to me is - does
it do anything to the life of the battery?

~~~
cliveowen
Mac OS X makes the stats available directly from the battery.

~~~
sengstrom
Yes, but how does it arrive at the number it reports?

~~~
rocky1138
One assumes by the mAh.

------
rcthompson
Hmm. I've already hit 100 cycles after only 3 months of owning my Macbook
Retina 13-inch...

I guess that makes me a ... power user? ;)

------
thehme
humm, I suppose I should not be too upset then about my Mac Book Pro's
battery. It is now a little over 3 years old and I just hit the 500 battery
cycles mark this week, about the same time that I noticed my trackpad is no
longer working properly. I have had the computer for a while and have not used
extensively for over 1 1/2 yrs (have work computer), so I am unsure what it
could be, but think it may be the battery. This year we have had a hot weather
in the East Coast and my laptop sit out in the changing weather (can't leave
the AC on for it), so this may have impacted the battery's lifetime. In
general, I can just add that for moderate average use, my Mac Book Pro's
battery has lasted quite a bit, but would have liked it to last closer to the
100 cycles promised by Apple's system specs.

------
spiritplumber
Replacing the cells isn't particularly hard if you are willing to take the
time with a dremel -- if you're clever you can then close the battery without
gluing it.

I still have a 4.1 macbook pro that I keep using specifically because it's the
last one they made with a user-swappable battery.

------
Cyph0n
I have a Mid 2011 MacBook Pro - so around 2 years old. According to iStat Pro,
it's been through 430 cycles with 93% battery health. As far as I can see from
the comments, I'm one of the lucky ones.

------
mchanson
Although battery health and maintenance is interesting I have never bothered
to nurse or baby my batteries on my equipment. If the battery gets to be too
short lived its time to replace it.

------
cinquemb
Are they're people out there that replace their own MB(P|A)? Is it possible? I
know there are hacks out there to take apart and fix chargers (I did it
myself).

~~~
nekopa
How did you fix your charger? I have always thought that we (users) shouldn't
have to worry about charging, over-charging, stretching the battery (I have
honestly heard people talking about this) and so on. We have the tech to make
smart chargers, why aren't they here yet?

{OT: has anyone else thought why we don't have a full bay size laptop battery
that can be put inside a desktop for those times the power goes out, but we
don't want/need a UPS?}

~~~
cinquemb
One of the wires broke inside of the magsafe. So with some pliers I opened it
up, then cut the broken part, strip the tip to expose the connection,
reconnected it (tested it and put some electric tape around it to be sure),
and assembled it back together with tiny amounts of hot glue on the edges. I
wish they designed things so they can be taken apart easier. I'm not sure if
this is really "fixing the charger" but some people decided to solder off the
tips connection to the board, cutting the bad part, and soldering it back (I
didn't want to do that much work).

I think for most users, they shouldn't have to worry about it, but I feel like
there should be the ability in the hardware/software for users to have the
ability to maintain/mod their own systems if they please.

------
andrewflnr
I'd like to see the Air-vs-Pro graph in terms of mAh instead of percentage of
factory capacity. Better yet, in terms of expected running time on a full
charge.

------
netcraft
anyone know how to do something similar on a windows laptop?

~~~
jbert
I'd guess:

\- write a little code to drive this API:
[http://stackoverflow.com/questions/7785096/read-laptop-
batte...](http://stackoverflow.com/questions/7785096/read-laptop-battery-
status-in-float-double)

\- and either use a task scheduler to run your code every minute, or startup a
long-lived process which just does this and sleeps

\- output in whatever format you like. CSV is obviously good, but given richer
APIs on windows you could dump it straight into an excel sheet I guess.

~~~
Scaevolus
RRDTool is great for storing these sorts of time-series archives, and it will
generate pretty graphs as well. You could cobble together an app starting from
these StackOverflow postings:

Task Scheduling:
[http://stackoverflow.com/a/2725908](http://stackoverflow.com/a/2725908)

RRD interface:
[https://pypi.python.org/pypi/PyRRD](https://pypi.python.org/pypi/PyRRD)

Battery reading:
[http://stackoverflow.com/a/6156606](http://stackoverflow.com/a/6156606)

------
OMBUG
Nice article, might start tracking this too! My mid-2011 MBA is at 203 cycles
and 99.5% capacity. Seems to be holding up remarkably well.

------
rednukleus
This is why I prefer replaceable batteries. Ultrabooks look nice, but
ultraportables are more practical in my opinion.

------
Axsuul
My 2012 MacBook Air on a full charge only lasts 2-2.5 hours during an intense
coding session. Am I the only one?

~~~
jlgreco
That probably depends wildly on what an "intense coding session" entails. Do
you have an IDE that is keeping your CPU pegged by constantly rebuilding
everything every time you enter a character? Or do you code in Vim and build
every few minutes at the absolute most?

------
kingsofwildcat
I didn't realize battery replacement was such a thing. I have 1856 cycles on a
2008 aluminum macbook with 'normal' health and have never noticed problems. I
gather from here [1] that I should be well into my fourth battery?

[1] [http://support.apple.com/kb/HT1519](http://support.apple.com/kb/HT1519)

------
Zoomla
where are those fuel-cell powered laptops?
[http://techland.time.com/2011/12/23/apple-posits-fuel-
cell-p...](http://techland.time.com/2011/12/23/apple-posits-fuel-cell-powered-
laptops/)

------
arxpoetica
Hilarious that I thought to post this on HN, and there it was, at the top...

------
ballard
2010 MBP MC374LL/A :: Cycles: 393 Health: %87

------
bradjohnson
Link is dead for me, mirror?

------
sixothree
Is this guy really a developer? I can't imagine using a single 15" monitor to
accomplish anything at a productive pace.

~~~
__david__
That's funny, I can't imagine being tethered to a single spot and
accomplishing anything worthwhile!

Snark aside, I love big monitors as much as the next guy, but I've seen very
productive developers that never even maximized their code window, let alone
used multiple screens.

Getting in the flow is _way_ more important than having a nice setup.

~~~
sixothree
Portability is important to me too. Our business continuity plan accounts for
disaster scenarios. My development machine is a laptop (17") with 24" monitor
and another machine with 24" monitor all using one keyboard.

Maybe it's the type of work that I'm doing is very technical but there's no
way I could actually do this much work on a small screen.

