Slashdot Mirror
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.
- 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.
1) It's "without further ado," not adieu.
You're making much adieu about nothing.
Cockadieudledoo!
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...
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.
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
I love studies with a sample size of one. No statistics, no variability. Definitive.
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.
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.
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.
While a bearing failing out of the blue for something like a cam or crank shaft it is exceedingly rare if they kept oil in the car stuff like water pumps, and alternators are basically consumables and just wear out and aren't too expensive to have replaced. I also get your point about people unnecessarily beating on their vehicles I see the same things. The one that gets me is when the engine first catches it's like they are in a drag race out of their parking spot, let the engine run for a couple of seconds and build oil pressure. My point was that most people should realize that it is much cheaper to maintain your vehicle than it is to replace it and that little problems like little squeaks, rattles, and squeals are a lot cheaper to fix than when what ever was rattling, squealing, or squeaking fails in a catastrophic manner.
For example if a wheel is making noise have it checked either by a shop or your self if you know what to look for and make the noise go away:
It might be the pad wear indicator just starting to scrape (replace the brake pads and enjoy your new found stopping power) It might be that you have run the pad backing into the rotor in which case you avoided a very bad problem but you might need you hearing checked since it got this far
The bearing might just be a little dry in which case greasing it solves the problem
If the bearing is completely dry you just avoided a very bad problem
If the needle bearings are gone you just avoid a very bad problem but why did you wait so long as it should have been making nose for a while so go get your hearing checked
Time to offend someone
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.