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Studying the Slow Decay of a Laptop Battery For an Entire Year
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."
You're discharging it wrong, don't do that.
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.
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.
Ha, I actually stopped reading at "Without further adieu". But that says more about me than the author, I suppose...
Gosh, thanks. That must be why the other ships call me Meatfucker -- GCU Grey Area (Eccentric)
He finds the failure of a product he paid good money for fascinating, rather than infuriating.
- 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.
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.
1) It's "without further ado," not adieu.
You're making much adieu about nothing.
Cockadieudledoo!
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.
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...
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.
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.
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.
No kidding!!! What do you say at this point?
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? 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.
Taking guns away from the 99% gives the 1% 100% of the power.
Apple get the same batteries from the same places everyone else does. They're as fungible as AAs at this point.
No kidding!!! What do you say at this point?
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
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.
E pluribus unum
I love studies with a sample size of one. No statistics, no variability. Definitive.
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.
No kidding!!! What do you say at this point?
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.
Please help metamoderate.
Alt-F4... Give me a little credit, will ya? I'm running Mint on my MBP, you insensitive clod!
Gosh, thanks. That must be why the other ships call me Meatfucker -- GCU Grey Area (Eccentric)
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.
For new laptops these days, we use 80% or 85% as the threshold before a charge cycle takes place. The default for Lenovo is 96%. Most of our users spend 80% of their time tethered to a power cable, and charging every few days after it trickles down to 96% is just silly (and bad for the battery).
Wolde you bothe eate your cake, and have your cake?
can be found at http://batteryuniversity.com/learn/
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.
I've never bought a Mac with RAM fixed to the logic board; and with pretty much every Mac I've ever bought, I've bought it with the minimum RAM configuration and then gone third party to top it up either immediately or within 2 years -- usually saving a few hundred dollars. The one thing Apple IS known for is overcharging for RAM. They've always done this, even back in the SIMM days. They argue that it's because they have higher standards, and thus you're only getting the best RAM from them. I've NEVER had a problem with using properly sourced cheaper RAM with a Mac.
It shows that you don't know the details of Apple's power delivery architecture. Magsafe-equipped Apple laptops are intentionally crippled in that the charger is artificially disabled if you use an unauthorized one. There's a chip in the magsafe plug that connects to the middle pin and is interrogated by the system management on the mainboard. If the interrogation fails, you can still use the power source, but the charger is disabled.
All it takes not to charge the battery is to cover the middle magsafe pin. I've done it by keeping in use one charger with a bad magsafe plug where the chip had died. Died how? Ah, exposure to the saliva of a 1 year old, he liked to lick those plugs, they admittedly taste "funny" since they are energized :)
That way you have the best of both worlds: you don't lose your work if the magsafe plug is kicked loose, and you don't charge the battery if you don't want to. Win-Win.
A successful API design takes a mixture of software design and pedagogy.
It's not the charging that is the issue, it's heat from the laptop. If you removed the battery and just stuck it in an oven at say 40C it would degrade. Batteries are chemical devices, they react to temperature.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC