
The life and death of a laptop battery - wielebny
http://people.skolelinux.org/pere/blog/The_life_and_death_of_a_laptop_battery.html
======
mizzao
For some reason, despite the fact that keeping a Li-I battery near full charge
and in high temperatures drastically decreases its capacity over time, most
laptop (and phone) manufacturers don't bother to have battery management
software (to limit state of charge). I only know of Windows drivers for Sony
and Lenovo.

[http://superuser.com/a/664583/32370](http://superuser.com/a/664583/32370)

This is probably because of some sort of planned obsolescence - they want you
to replace your device.

On the other hand, in electric cars (using the same battery chemistry), where
it is in the company's best interest not to replace the battery, it is charged
to a maximum of 70-80%, except when soaking up extra energy going downhill,
and basically maintains its full capacity for much longer.

~~~
tedunangst
Well, people also complain (extremely loudly) that they paid for a 50Whr
battery, and by golly, they mean to get 50Whr of power out of it! They're not
going to let some slick talking corporate drone trick them into believing they
should only use half of what they paid for.

Practically speaking, even assuming my battery did idle at 50% sitting on my
desk, what happens when I decide to take it out to the coffee shop (or the
airport!) and want it at 100%? I don't want to micromanage charging my battery
and filling it up before I go out. I have enough fun discovering my car is
only ever out of gas when I'm about to depart on a long drive.

~~~
erikpukinskis
So why not have it as an option so people like you who don't want to have to
manage it can have it go to 100% and people like OP can stop st 80%?

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frou_dh
I end up punishing the batteries in my stuff with 100% -> 0% -> 100% cycles
frequently and don't feel bad about it. The battery exists to conform to my
needs, not the other way round! I'm not going to use my stuff in patterns I
find inconvenient just to baby an inanimate object.

~~~
malloreon
I do this too, but for me it works really well.

my 4 year old iphone 4 got 3 days on a single charge when I got rid of it.

My year old 6 still gets 2-2.5 days per charge.

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m1k3r420
Fantastic! I will be giving this a trial on my laptop. My laptop is running
Debian and it usually sits connected to the power all the time.

When I disconnect the charger I have seen estimated battery remaining times of
anything from 2 hours to 87 hours! However in reality it's more like 45
minutes :(

~~~
hmage
You do know that keeping your li-ion battery plugged 24/7 is best way to kill
it, right?

Do a full battery cycle at least once a month and you won't prevent the
catastrophe.

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

Storing a battery at 40 degrees C at 100% charge will degrade it by 35% after
a year. Drop that to 25 degrees C and it'll be degraded by only 20% after a
year. If it was stored at 40% charge instead of 100% charge that drops to only
4% degradation after a year.

~~~
frgewut
Why can't this problem be solved in software? OS knows that AC power is used
100%, right?

~~~
odabaxok
I believe a better question is: Why can't this problem be solved in hardware?
So, it won't depend on the OS and if I shutdown my laptop and leave it on the
charger it will still work.

My 3.5 year old Asus laptop has still similar battery life as it had when it
was new. I always keep it on the charger when I can and sometimes I just shut
it down and leave it on the charger overnight too (but this is rare). When I
bought it, I have noticed that the battery was never above ~95%, but I have
never studied how it works exactly (is it done by HW or by the driver). I have
used it with Win7, Win8, Win8.1 and now Win10.

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habosa
Wow down to 7% of original capacity? I've always had battery woes but that's
exceptionally bad. If you started with 6 hours now you'll get 25 minutes of
battery life!

Does anyone know of any good power management software for Linux? I am about
to get my first Linux laptop and this is one of my primary concerns (since the
laptop is designed for Windows 10).

~~~
JupiterMoon
If you have not purchased already I strongly recommend re-considering and
buying a made for Linux laptop. Putting Linux on hardware intended by the OEM
of Windows is not always a good idea. I've not tried them yet but my next
laptop will come from System76 (unless I see something better before then).

~~~
001spartan
Unfortunately, I can't recommend a System76 laptop. I use the Galago UltraPro
as a work laptop, and it is not an enjoyable experience at all. The
construction is flimsy, and the keyboard is _terrible_. I have never used a
worse keyboard on a laptop. I wanted to love it, but I can't recommend it at
all.

~~~
eutropia
Wait, did you ever get the replacement keyboard the mailed out for free? I run
an ultrapro as well, and they sent me the redesigned keyboard without me
saying a thing.

~~~
001spartan
This was after they replaced the keyboards. The keyboard is still terrible.

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m_sahaf
My Lenovo's laptop (IdeaPad z410) battery is already dead, and I've had it for
a year and a half. When it had Windows on it, I get about 2 hours of battery
time. After I fully installed Ubuntu, I got 3 hours out of the same battery.
Now it never charges, always stuck at around 1%, and it shows that it has a
capacity of only 11.4%. Two of my previous laptops' batteries degraded after
the second year. This is the first time I have a laptop whose battery dies in
less than two years. We have a trend here (as it seems from skimming the other
comments).

~~~
mizzao
Usually when you install Linux on a laptop you can expect any software (non-
firmware) battery management to go out the window.

~~~
m_sahaf
And that's a shame. Battery management should be on the hardware level. I
can't find any information whether detection of AC-charger presence is on the
hardware level or not, which I also think should be on hardware level to stop
charging once the battery is full and fully draw current from the charger.
That will not waste the battery's cycle life. Both of these speak for the
overall quality of the manufacturers' products.

~~~
emn13
"should"... doesn't buy you much. It's a shame there's no standard driver for
this, however, since these Li-ion batteries are all pretty much the same in
terms of charge management. It's a safe bet almost all users would be better
off with a batter that defaulted to around 70% charge unless explicitly (and
temporarily) told to prepare for a long trip.

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artmageddon
How do most people manage their devices(iPhone / MacBook / etc.) if leaving
them plugged in all the time is detrimental to the battery? I _could_ kill all
the apps on my phone and put it in flight mode when I go to sleep, but I may
not get the chance to charge it to full if I have to leave the house
immediately upon waking up. Should I let my battery drain all the way?

~~~
kijin
Leaving laptops plugged in all the time doesn't seem to be particularly bad
for the battery, as long as (1) the laptop doesn't get too hot, and (2) you
actually keep them plugged in all the time, rather than switching frequently
between plugged-in and battery-powered.

My Lenovo laptop has been plugged in for the last 3.5 years, only very
occasionally (once a month?) going on battery power for short periods of time.
Windows reports that I still have 91.7% of the design capacity. I'm not sure
if I should trust that number or not... but the last time I unplugged it, the
battery seemed to last at least 70% as long as it did when it was new, so it's
not totally off, either.

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vxNsr
Windows 8+ has a similar feature built in, to generate your battery report you
just need to go enter powercfg /batteryreport in cmd

Windows 7 can also generate power reports (powercfg -energy) but it's a little
less human friendly

Unfortunately for me it appears that installing windows 10 reset the stats, as
my report only goes as far back as about a week after I installed windows 10.

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Hnrobert42
Very impressive. Concise, thorough, useful. I love seeing posts like this.

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kalleboo
7% remaining capacity after 2 years seems insane to me. I replaced my 2012
MacBook Pro battery this year as it passed 1000 cycles (I'm bad at plugging in
and end up charge cycling daily) and even that battery was still above 70%
capacity...

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mironathetin
Interesting.

Did someone follow the link to the Macbook Air? It shows that the Mac battery
lasts much longer than the Thinkpads. My impression is similar: my Thinkpads
(back when IBM still labelled them) where down after 2 years. All Powerbook or
Macbook batteries that I ever had still did well even after 3 years.

Shocking, on the other hand, is the amount of detail of the battery usage
records that apple stores. Imagine apple had access to them.

~~~
masklinn
One of the things Apple seems to be very good at is managing battery
"overcharge": my 5 years old MBP reports ~90% battery capacity but a
relatively low amount of cycles (~200) because it's almost always tethered.
Other companies seem to handle that less well and have the battery health fall
much faster.

~~~
bukubb
Here's a link to my MBA performance:
[http://imgur.com/2UVFmIU](http://imgur.com/2UVFmIU)

Bought Nov 2013, now has over 250 charge cycles and is still at 90% of
original capacity.

~~~
snowwrestler
How would I generate this graph for my MBA?

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spheniscus
For each of my laptops, I use two batteries: a high-capacity one that I use
when traveling and a regular one for daily use. When unused, I store the high-
capacity battery (charged to about 40%) in the fridge, wrapped in a plastic
bag. Thanks to this treatment, the 9-cell battery of my old spare laptop (Dell
D430) is still good for 4-5 hours of use. It lasted for 6 hours when I bought
in 2008.

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vinceyuan
(I know this post is about linux.) My windows laptop batteries usually die
after 2 years. I think Windows laptops have the problem of overcharging. To
avoid it, I have to unplug the battery when I need to use a laptop as a
desktop. We have to admit Apple does good job in battery management. My 2010
MacBook Pro 13-inch's battery is still in good condition (relatively).

~~~
lucaspiller
> My 2010 MacBook Pro 13-inch's battery is still in good condition
> (relatively).

My 2006 MacBook still holds about 30 minutes of charge in the original
battery. Most of the time I left it plugged in all the time, what do people do
that kills them so quickly?

------
explorigin
My wife's Lenovo has a windows utility that allows you to default the charge
max to 60%. My Dell has a similar option in the EFI settings.

After about a year, there has not been a noticable degradation in battery life
(and I have noticed it in past laptops).

~~~
usrusr
This should be the norm for all devices with built-in lithium battery
charging. Default to a low attrition end voltage, and a simple hardware
control to temporarily enable full capacity charging in anticipation of a
particularly long off-grid phase.

But dead batteries are what keeps the economy spinning, so it must be in all
our best interest that the self-optimizing algorithm of capitalism decidedly
skips on this particular efficiency gain, right?

------
pcurve
IBM Thinkpad actually has pretty good battery reporting tool that tells you
condition, minutes-to-charge, cycle count, voltage, current, capacity Wh,
temperature, mfr. name, mfr. date,design voltage, firmware, etc.

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zamalek
Pro-tip: suspend is not zero power state and can hurt your battery. I used it
on my first work laptop and ruined the battery (brand new) in 1 year. Use
hibernation.

~~~
lucb1e
Tradeoff between killing your battery or killing your SSD then I guess (if you
have an SSD of course). And wasting time when booting, my experience with
hibernation is that it isn't _that_ much faster than a cold boot. Suspend is
more or less instant.

~~~
briHass
I wouldn't worry too much about write endurance with modern SSDs - at least if
you're not using them in a server or something. The Samsung 850 EVO (not even
the PRO model) is rated for 150TB, and most tests got closer to double or
triple that number before the drive failed.

If the full contents of a 16GB memory are written to disk for hibernation
daily, with say another 50GB of work, that's over 6 years before you hit the
lower limit. I probably wouldn't trust a hard disk that was used that heavily
for that long either.

~~~
gambiting
I've written 40TB so far to the 1TB 850 Evo in my workstation and it certainly
has problems now that it didn't have before - it just hangs for a few seconds
at a time, when copying or deleting large number of files. Not sure what it's
doing.

~~~
cdr
If by chance it's an 840 (rather than the VNAND 850), there's been two
firmware updates to improve performance over time - make sure to update the
firmware.

