Ask HN: Should I unplug my laptop charger at 100%?
I have talked to numerous people and there is no set consensus on whether I should be unplugging my laptop charger when it is fully charged.
Disclaimer: my knowledge of the field is from ca 2010.
1) Lots of deep discharge cycles do negatively affect battery life. Try not to jump between 0% and 100% too much.
2) Li-ion batteries do not love being at 100% SOC (state of charge). As batteries become more dense, the membranes become thinner. High SOC equates to high chemical potential, which will break down membranes faster. As such, avoid leaving your battery at 100%. This wasn't as much of a problem with older batteries with thicker membranes, but is becoming more and more an issue as we try to squeeze every ounce of density out of batteries.
3) Roughly 70% SOC is where a battery is happiest, but the whole range of ~30-80% is pretty happy for a li ion cell. Try to keep your battery at ~70% or so overnight, at 50% or so for long sleeps.
A good usage pattern: plug in and let charge to 90%, unplug and use for a couple of hours, plug back in at 50% or so, rinse and repeat.
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).
or set your power drivers to do it for you.
Pray tell me how. (Macbook Pro 2010.)
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.
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.
By the way, my battery health is also around 85% after 500 cycles and being plugged in and charged to 100% whenever possible.
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.
100/8460*7633 or 90.22%
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.
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}' 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)"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)
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.
I use it on my Samsung given that I don't really need +5 hours without plugging anyway.
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.
* 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)
Also unplugging/replugging is annoying, get a brand/model that already has the charging cap option and just ask to enable it.
In my experience there can be memory effects when fully capping at 80% over the years, though.
Great. Another reason to avoid barely-one-day batteries on phones. They'll die sooner!
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."
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.
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.
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...
Well isn't this what computers are good at? I thought modern computers had a microcontroller for doing this...
(Incidentally, I'm at least a bit curious myself as to the answer, and have my own pile of conflicting anecdotes I've read.)
True science, that is, proposing hypothetical models, analyzing results, and admitting no real results can be drawn due to insufficient model complexity, has been thrown out the window by pride and laziness.
First, we need to start by assuming a sphererical laptop...
The question is simply "what do we know about this problem" not "what is the absolute unquestionable universal answer."
Also your comment has some interesting points but starting off by comparing statistics and citations to bible quotes and racial stereotypes isn't going to win you much support.
Do that enough times, and you'd quickly have the smartest site on the Internet.
This thread literally has people posting links to Yahoo Answers.
— https://web.archive.org/web/20110521104819/http://www.apple.... via http://apple.stackexchange.com/a/12280
This could also be useful, but doesn't answer the question directly: http://www.apple.com/batteries/maximizing-performance/
The actual preference for getting the MOST DISCHARGES out of a lithium ion battery is discharging it to 50%. This, however, doesn't not to equate to longest battery life (in terms of age) for the use within a laptop/phone.
Edit: There is something state of charge estimation models which may rely on this variable to decide how full they'll charge the battery. If you don't fully discharge and fully recharge the battery to update this capacity value, the SOC estimation model might overcharge the battery, thus decreasing the lifespan.
https://www.apple.com/batteries/maximizing-performance/
They don't say what "long-term" is, but monthly seems reasonable to me.
Also Apple seems to indicate that storage in a deep discharge state is far more damaging than storage at near-capacity based on the wording.
So if you're in doubt, charge it before you store it.
Finally, I don't think there's anything on that page that says you shouldn't keep your laptop plugged in when it's at 100%. I would be very surprised if they didn't have some cycle-conditioning going on. I have both a 2008 unibody and 2010 MBP, both essentially remaining plugged in for years. I don't think the battery life is abnormally low for their age, they still are capable of several hours of usage on battery.
That's why if you pay attention you'll often see your battery % go from 97%-100% and then back down to 97%. It is reporting as "charging" but in reality it goes idle to let the battery de-charge a little.
In short, leave it in because it's not worth worrying about.
I do leave small laptop on suspend overnight (not plugged in) and then I do use it on the train into work, so a small charge/discharge cycle each day.
The big typing box laptop (ancient T61p) is left on and plugged in a lot. May use a timer switch on the wall plug simply to reduce reliance on the overcharge protection in the battery/charger.
I think those with devices that have batteries that cannot be replaced may be more concerned.
I did go mid-way, buying high quality Japanese cells and installing them in a chinese pack. A bit cheaper than a new official battery, but required some work.
But yes, this is the only sweeping statement that could be universally applied. Anything else is just anecdotal and something to talk about at the next happy hour.
http://batteryuniversity.com/learn/article/how_to_prolong_li...
Summary:
Similar to a mechanical device that wears out faster with heavy use, so also does the depth of discharge (DoD) determine the cycle count. The shorter the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life.
To answer your question: No.
Side note: Don't blindly trust the manufacturer. Of course Apple wants you to wear out your laptop as fast as possible, once it's past the warranty. They're a business.
Side note 2: Laptops do NOT charge your battery to 100%. Your battery indicator is fake. 100% on your battery indicator is more like 90% in reality. The charger automatically cuts off before it reaches the true 100%, so all of the comments in this thread about 100% being bad are wrong, because no modern laptops will truly let you reach 100%.
If you never observe a zero (or, presumably, a 100%), it might recalibrate incorrectly. Again, this is based on old and uncited knowledge. There's surely someone here involved in writing power management software that could chime in.
https://answers.yahoo.com/question/index?qid=20130825212946A...
Lithium ion batteries do seem to have memory.
This has happened to several dell and hp laptops I've owned or used long term, but both apple ones still keep charges for close to 3 hours even around 3 years after purchase without replacing the battery.
It's certainly true that the old nickel cadmium batteries were harmed by continuous charging. But nowadays with lithium ion batteries, lots of laptops, batteries, and chargers all have little microcontrollers on them that can be smart about charging and maximizing the lifetime of the battery. The short answer is that you should read the manual that came with your particular system and see what it advises.
The problem with leaving it at 100% is that just sitting at full charge wears it out, it's better to just keep it within 40%-80% than to leave it fully charged.
If you really want to, you can do a little bit of good by letting it drop to 40=80% during periods of non-use.
Too bad that some batteries wear out even faster this way because of the heat.
I'm on an early 2011 MacBook Pro (purchased in March, 2011), which I've used for about 8-10 hours per day, 5 days per week, since the date I purchased it. I have about 6.5 hours remaining at a 91% charge (screenshot for proof http://cl.ly/image/1a2d2y2V1J2O). I consider this to be pretty good for a notebook that has been used extensively for more than 4 years, which is why I felt like I should share my advice on keeping your battery healthy (I do exactly this, and have since day one, except when I'm mobile and actually use the battery - about 2 times per month - today is one of those days):
1. keep your notebook plugged in all day while you work
2. unplug your notebook when you power it off at night
3. on Friday, unplug partway through the day, allowing the battery to drain to about 30% by EOD
4. Monday morning, start back at step # 1
In my opinion, you don't miss all that much except for the following features: * Software updates download * Time Machine performs backups * Spotlight perform indexing
http://batteryuniversity.com/learn/article/how_to_prolong_li...
I don't know how much reserve they keep on hand, but what your OS reports as 0% charge is almost never actually that low.
In other words you can use your battery from 100% all the way down to shutdown- but the more time it spends in the 40-80% range, the longer its service life.
This tells me that leaving your battery plugged in whenever possible is good, since it minimizes the number of cycles you're putting on the battery. If you unplug the battery once it's fully charged (and proceed to use it), you're just subtracting cycles from the battery's life.
On the other hand, apparently there's a cost to letting the battery sit at 100% charge for too long. I don't know how long "too long is", but Apple's battery site says this about long-term storage: "Do not fully charge or fully discharge your device’s battery — charge it to around 50%. If you store a device when its battery is fully discharged, the battery could fall into a deep discharge state, which renders it incapable of holding a charge. Conversely, if you store it fully charged for an extended period of time, the battery may lose some capacity, leading to shorter battery life." [2] Keep in mind this is specifically talking about long-term storage only.
Taken together, I interpret all this to mean that it's best to leave the laptop plugged in at 100% whenever possible, provided that you're occasionally taking it out and using it (so it's not "long-term storage").
That said, I'd love to see some quantitative benchmarks to confirm all this. ;)
References:
For example: Discharging the battery fully might yield 200 cycles, but discharging a battery 50% might yield 500 cycles. Obviously with the 50% discharge, you're only using half the capacity, but when you multiply the number of cycles by the capacity used, you can compare them.
The software I wrote has configurable alerts so a user can get an alert then it's reached a certain change level (like 90%) and then again when it drops below a certain level. Users have specifically ask for that so they can unplug without over-charging.
The feature to show remaining battery and charge time is what I really enjoy about it.
I call malarkey on all of it. I've had my laptop plugged in for years and it sits at 100% most of the time. I don't have time to deal with that kind of hassle, even if it is true.
Great idea, except that if you forgot to turn this feature off and had to leave, you might leave the house with just 60% battery life.
https://forums.lenovo.com/t5/image/serverpage/image-id/34801...
Letting the battery sit at 100% wears it out more than sitting at 40-80%.
It's not right to assume that also applies to in-use products, especially the way people use them. In fact you'd likely reduce battery life because you're putting the battery through a greater depth of discharge (DoD). Assume you let it run from 80% to 60%, you've just gone through a cycle of 20% discharge when you could have kept the DoD at 1%. Also, most modern laptops will run on power once charged, so it's not like an infinite number of 1% cycles.
http://batteryuniversity.com/learn/article/how_to_prolong_li...
From the previous answers to this item, it would seem that most vendors focused on long life unplugged (6 hours! 10 hours! So long, you'll forget where you last put the cord!) and "you'll have to buy a new battery... and they aren't cheap" if you stay plugged in.
While part of me finds that hard to believe, another part wonders if this is just a part of the wonderous circle of (battery) life. Luckily, the conspiracy part left the building, or he would have said that the evil vendors do this on purpose to keep a steady cash flow.
Sorry, didn't mean to evoke this earworm: https://www.youtube.com/watch?v=8zLx_JtcQVI
My current ThinkPad w540 does not seem to do this in Linux, so I suspect that either Linux or Lenovo has solved the problem, but I haven't really investigated what happens. I leave my ThinkPad plugged into a dock most of the day at the office like I did with the W700, but it's battery still has almost full capacity a year later and can still keep it running for 5+ hours on a full charge. (Linux could never get the 7+ hours that it can get under Windows and I haven't run Windows for more than 1 hour in almost a year.)
http://batteryuniversity.com/learn/article/how_to_prolong_li...
A lot of a people seem confused about two concepts in the article: ideal storage and depth of discharge. These are two separate concerns. If you try to maintain the ideal storage charge while it's in-use (say 40%), you're going to end up wearing your battery by putting it through unnecessarily deep discharge cycles.
Unless you want to plug and unplug every few minutes, you should probably just leave it plugged in.
However the reason I know this is the same reason I keep mine in: I've dropped every laptop I've ever owned on the floor multiple times, and I've had one or the other of battery or charger cable fall out at least once for all of them, at least with the battery in the chances of losing power is reduced (though I have on occasion had both fall out at the same time).
Oh, if only that were true...
After 201 full charge cycles in ~2 years (trickle charging at 100% takes awhile to equal one cycle) I'm still at 95% battery life.
My take is that, at least for MacBooks, it doesn't make nearly as much difference as not letting your computer sit in a hot car a lot and other standard battery hygiene things.
From a realistic perspective, though, I've found that (in my experience) to be marginally beneficial; the slight benefit to battery health it had afforded to me wasn't worth the hassle.
However, if you still insist on doing it by yourself, take a look at my hardware-level solutions at http://softwarerecs.stackexchange.com/questions/10441/laptop...
Also one (lame) for bat stats on linux: https://gist.github.com/cmavr8/bdf591d8dc66290ae87a
Chris
1. A lithium ion battery charger is smart, it will not overcharge or harm your battery in any way keeping it charged.
2. In terms of discharging a lithium ion battery - they are not susceptible to memory like ni-cd and ni-mh batteries, so regular discharging is not required.
3. Apple and other companies will suggest discharging your lithium ion battery fully. The reason being that a complete discharge followed by a full recharge will update an internal counter which records the capacity of the battery. The capacity decreases over time, so your battery charge indicator will need this full discharge/recharge regularly to stay accurate. Not important for actual capacity you get out of your battery.
4. There is a recommendation that in order to get the MOST NUMBER OF DISCHARGE CYCLES out of a lithium ion battery, you should only discharge it to 50%. I put MOST NUMBER OF DISCHARGE CYCLES in bold because it is important to know that this is the most important factor in the life of your battery - you do not need to discharge the battery to 50% in order to get a longer life, but if you do need to discharge it, 50% discharge is optimal to avoid any damage by over-discharging. If you discharge your battery EVERY day because you charged it to full, you are going to severely decrease the lifespan.
5. (Edited in) Laptops and phones use a State of Charge estimation model to decide how full the battery is. Depending on the device, the manufacturer may suggest fully discharging and fully recharging the battery so that the estimation model understands the capacity of the battery and avoids overcharging: http://chargedevs.com/features/the-challenges-of-battery-sta...
My recommendation: Don't discharge when it is full. Only discharge when you need to. Charge it at 50% if possible to avoid over discharging. KEEP IT COOL - heat kills batteries lifespan as well.
Battery technology has changed a lot since I worked in the industry - they're always advancing and changing. There are many resources to keep yourself well informed: http://batteryuniversity.com/learn/article/how_to_prolong_li...
Edit: All applications and devices are different. My recommendation might not be the best - some have suggested avoiding keeping your battery at 100% constantly, whereas my suggestion assumes that the charger won't harm the battery by overcharging. For example: battery is at 100% on the device, but in actuality it is sitting at 90% state of charge in the context of lithium ion technology.
Heat transfer from the device it's plugged into.
To maximize the life of the battery, do the following:
Use the battery until the charge is completely
depleted--until the battery status indicator starts
blinking orange.
Recharge the battery completely before using it.
The battery is fully charged if the battery indicator
shows green when the AC adapter is plugged in.I think I just found my project. Stay tuned!
Thus, the longer you can preserve your cycles, the longer your battery will survive.
You can also read this thread: http://www.reddit.com/r/askscience/comments/1snzg1/is_it_act...
when i called apple to replace the battery on warranty because it had started to bulge/swell dangerously and not hold charge, they had me open up the system information panel to see how many cycles it had been through, and it was hilariously low, like, 4. they refused to warranty it.
so at the very least, if you care at all about your warranty coverage, you should probably cycle it normally.
The battery lost 50% of its capacity. The laptop was almost exclusively used while connected to the charger.
So if there hasn't been a big change in how laptop batteries work in the last few years I'd recommend removing the battery whenever the charger is connected if possible.
I've always had laptops plugged in all the time (desktop replacements) for months at end, with the battery acting as a UPS.
When first disconnecting the power adapter, the batteries always discharged much faster than they should. After a few cycles, they went back to normal.
I believe that leaving a laptop plugged in all the time is better for the battery than doing complete discharge-recharge cycles (5-100%).
Hi Zatkin,
General advice: please study the materials hosted at the following great "Battery University" website: http://batteryuniversity.com/
The charge and discharge protocols which are best for battery life and capacity depend on the kind of battery.
Certain batteries benefit from being cycled, like NiMh and NiCad. It's not that important for lithium, IIRC.
Some batteries benefit from priming: treating the battery in a certain way when it is brand new, so it lasts longer and performs better over its lifetime.
(I could use a refresher myself; I'm going to study the materials on that website.)
I know there can be a fine line between a good, thought-provoking question and a useless one, and, to me at least, this seems too far on the "useless question" side of things. It's about basic hardware maintenance, and I'm honestly surprised it's gotten 37 points in 22 minutes (so far).
People are free to down vote me (and they have) for my opinion -- even though I've been polite and (I think) thoughtful. Even still, my opinion stands: HN is the wrong forum for this kind of question. There are many, many questions that HN isn't the place for... How should I charge my car battery? What's the best electric blanket? Should I use 10 or 12 gauge wire wire for my house? Maybe it would be a good question if the OP had researched it a bit first, and posted "surprising facts about your laptop battery" or something. But just a question about laptop batteries?
Each one of these kinds of questions takes away from better quality, thoughtful or surprising content, which is what I like most about HN.