However, i'd rather buy a new battery after 5 years (if my laptop is still fit and the battery is dead), than having to complicate my life and think about when to unplug or charge my laptop multiple times each day for 5 years...

My Macbook air from mid 2011 is currently at 100/6700*5629 = 84% battery health. (6700 = design capacity, gathered from "ioreg -l -n AppleSmartBattery -r".

I see some similarities to, e.g., medical pronouncements that some particular food increases risk of cancer. It's easy to get alarmed, but there's a big difference between it increasing my likelihood of getting cancer by 0.05% and making cancer, say, (just to illustrate the point) 100 times more likely. The former I would likely ignore and the latter would probably make me give up the food instantly.

If you are willing to mess with drivers, you may want to try installing Linux. On a 2013 Air, battery life and performance (even graphics!) are surprisingly better with Debian Jessie than with OS X. Of course, it is a newer model than yours, but the drivers will only be more stable and mature with a 2011. Especially if you have 4 GB RAM and you're running into a memory barrier with OS X, you should see a significant improvement.

Always 'Quit' open apps you don't use, never, NEVER have 2 sessions open at the same time, and try using lighter applications when you can (VLC instead of iTunes for music, Skim instead of Preview for PDFs, Preview instead of Photos for images, etc)

I have to use a 2012 MBP with Yosemite from time to time and if I follow these rules it is definitely bearable.

By the way, my battery health is also around 85% after 500 cycles and being plugged in and charged to 100% whenever possible.

  ioreg -l -n AppleSmartBattery -r | grep -i capacity

  "MaxCapacity" = 8329
  "CurrentCapacity" = 8002
  "DesignCapacity" = 8440

    100 / DesignCapacity * MaxCapacity

    MaxCapacity / DesignCapacity * 100

    98.68%

    echo $(ioreg -l -n AppleSmartBattery -r | grep MaxCapacity | awk '{print $3}') / $(ioreg -l -n AppleSmartBattery -r | grep DesignCapacity | awk '{print $3}') \* 100 | bc -l

    ioreg -l -n AppleSmartBattery -r | awk '/MaxCapacity/{mc=$3};/DesignCapacity/{dc=$3};END{print 100*mc/dc}'

After reading this thread I try to keep my battery at a 50-80% charge :)

Except when I do some CPU intensive stuff like compiling or rendering, then it is being charged thought the process.

    upower -i /org/freedesktop/UPower/devices/battery_BAT1 | grep capacity | awk '{print $2}'

    upower -e

    bc -l <<< "100 * $(cat /sys/class/power_supply/BAT*/energy_full) / $(cat /sys/class/power_supply/BAT*/energy_full_design)"

100/8460*7633 or 90.22%

http://atp.fm/episodes/33-a-30-minute-skip-button

TL;DR: good idea, but people will forget and become shitty when their laptop isn't at 100% when they go on a trip.

My thinkpad has a mode for keeping a healthy battery that stops charging at 90%, then trickle charges to keep it there (it also allows for fine tuning of this behavior)

I use it on my Samsung given that I don't really need +5 hours without plugging anyway.

As an aside: the mechanism works in slightly different way (at least on all of my 4 thinkpads of different generations). There are two thresholds, maximum battery capacity when charging can start and capacity when charging stops, the aforementioned application even seems to have some kind of logic to set these thresholds according to battery aging.

Also, trying to keep Li-ion cells charged to constant state of charge is not good for their lifespan. What is commonly known as trickle-charging (charging by infrequent, short but large pulses of current) is actively discouraged by most cell manufacturers, sometimes even citing safety reasons.

* Devices marketed on how long they last on a single charge, but much less often on how quickly the battery degrades * Batteries are a later upgrade upsell opportunity * I would not be surprised to learn that a significant number of device upgrades start as simply wanting a better battery (but why not upgrade at the same time)

I mean it's one thing if my OS can control the charging cycle to some extend, whether Apple can install drivers (and bad guys bad stuff) on my Battery "smart" board.

It may seem like a big leap now, but I bet someday (or perhaps even now, why do people place tape on their webcams otherwise) it could become a problem.

But of course, to my knowledge so far Apple is doing a pretty good job in keeping Macs and OSX kind off secure (don't quote me on that), however than again I don't want OSX to become as restrictive as iOS or I'll have to switch to Linux t get my dev-tools working. (not a fan of that personally)

If a charger could be tweaked to charge the battery slowly and not overcharge it, that'd be the ultimate solution.

SOC is relative to the application, but it is possible many applications nowadays purposely operate within a specific SOC and not exactly 0-100%. We need an Apple battery engineer in here to confirm ;)

Edit: You already acknowledged this elsewhere.

So I'm reluctant to agree or confirm with any sweeping statement about a single variable (in this case, heat generated by charging), because it may be true in some cases but not in all. And it also depends on the specific battery.

Most likely, for most laptops, for most daily use-cases, and a charging pattern of 90-50-90 in 2-3 hours, I'd rather take the slightly increased temperature than keep the battery at 100% for that time period.

But again: it depends. On so many things.

Edit: also, either case (keeping at 100% for 3 hours vs 90-50-90 for 3 hours) is better than keeping at 100% 24/7. So no harm done if you can't decide which is better. Just A) don't plug in all day long and B) don't go crazy with the heat and you'll be fine.

Quote: "If you primarily use your computer with the AC adapter attached and only infrequently use battery power, battery deterioration may occur faster if the battery is constantly charged at 100%. Lowering the charge thresholds for your battery, periodically resetting the battery gauge, using Maximum Lifespan mode, or using Battery Health Mode will help increase its lifespan."

But how do I know the battery reports honest numbers? If all these years spent dealing with hard disks tought me anything, it's that what's being reported by the device could be totally different from the reality :)

Perhaps some brands charge a premium for a "long lasting" battery whose only actual difference from a regular one is a firmware hack that keeps it at %80 charge? Can I actually know this?

http://en.wikipedia.org/wiki/Write_amplification#Over-provis...

How long until the power plug, or the receptacle in the laptop, wears out?

How expensive is labor to fix the receptacle, compared to the cost and convenience of replacing a battery?

Unless the OS manages this for me (and maybe it does behind my back?), I'm not going to bother. But many thanks for the interesting writeup.

Keep your laptop cool, perhaps even consider battery saving options while plugged in if you find it is generating too much heat.

Edit: A running laptop will cause heat, so shut it off when not using it. A plugged in laptop shouldn't create much more heat than a laptop running on battery power, if anything, the battery should be cooler when plugged in and fully charged (assumption made).

If you actually deep discharge a lithium battery to 0%, think they'll sometimes have problems taking a charge again. You see this occasionally when someone has taken to 0% on the meter, then let it self-discharge on the desk for a long time.

In my experience there can be memory effects when fully capping at 80% over the years, though.

Also unplugging/replugging is annoying, get a brand/model that already has the charging cap option and just ask to enable it.

Well isn't this what computers are good at? I thought modern computers had a microcontroller for doing this...

Great. Another reason to avoid barely-one-day batteries on phones. They'll die sooner!

or set your power drivers to do it for you.

Pray tell me how. (Macbook Pro 2010.)