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Macbook battery burnout? Not advised to always have plugged in?

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I am working on building my first real computer-based music system, have bought a used Macbook to use as a server, and am currently re-ripping my 600+ CDs into AIFF (they didn't transfer so well from WMA lossless on the PC despite several different attempts and methods). I was recently told by one of the younger set who has grown up on Apple products (my financés 18 year old daughter), that it is not a good idea to always leave a Macbook plugged in as it will ruin the battery and the power cord will fry besides. As it is my plan to use this laptop strictly as a music server in a single location and plugged in 100% of the time, that would put a crimp in things to say the least. If it makes any difference, it's a black Macbook 2GHz with 2GB of ram, 160 GB HD (temp storage before I add the Thecus N5200B Pro) and running OS X.


On top of that, I've been using a PC laptops professionally for years, most of the time mounted to docking stations (except when I travel 6-8 times per year) and with never a problem.


Can anybody confirm or dispute her claim? Any and all help would be greatly appreciated.


Much obliged.





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the power cord will fry

Put your hand on the power cord, if you get a burn, it runs hot indeed.

If not, you know the value of the advice.

Batteries might loose their capacity when charged permanently (memory effect). The modern lithium ion type don’t have this problem.

There has been several recalls of batteries because some of them exploded.

If this worries you, try running without the battery



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Hi Martin - I wouldn't heed that advice. Maybe back in the 90s it would have been appropriate, but not anymore. It may be healthy for a battery to be drained and recharged once in a while, but with newer Lithium batteries the effect may be negligible. It's not like the battery is constantly being pumped with juice when it's charged. Computer designers are smart enough to recognize a battery no longer needs power when it's fully charged. Also, check the product manual it wold likely say if this was a bad idea. Plus, most Apple laptops are designed to work with an external monitor and some require the laptop be plugged into the power outlet for this (my MacBook Pro & 30" display).


One interesting thing to note is Apple recommends using its laptops with the battery in at all times because the laptop will actually dip into the battery's power under certain circumstances like extremely heavy loads. This was in the manual for my MacBook Pro.


Founder of Audiophile Style | My Audio Systems

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Even lithium batteries tend to be easily damaged if put continously on AC and with warm/hot temperatures, which are easily reached within the case of a laptop.

some dock stations work in order to avoid full charge of batteries or alternate small cycles of charge / discharge; this is why your laptop may have survived all those years still being always plugged in.


take a look at this article from tesla motors (those who have created the first really competitive li-ion electric car) and you will learn a lot about li-ion batteries. In particular, second and third lines of section "calendar life", where they also refer to the laptop batteries.



in my opinion, if you were planning to have always the computer in a fixed location, an imac instead of a macbook would have been better, however if you let the battery discharge completely and recharge for 2-3 times a week this should preserve your battery life for long time.


As regards the cable frying, it's a bull**it


hope it helps :)




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I really appreciate your help. As my Macbook was purchased used, I don't have a manual, so your comment is very helpful. I also very much appreciate the insight from another regular contributor, Roseval. And to top that off, Francesco weighs in with the Tesla link, and his assistance with different ways of thinking about battery life. I almost feel as if I've hit the trifecta!


Anyway, I think your question to Francesco about weighing overall battery life by being constantly plugged in vs. known cycle times really goes straight to the heart of the matter, and I am most interested in reading his answer.


Thanks for hosting such a terrific site. I've learned more here than I've learned almost anywhere else, and I know now I have lots more ground to cover.


No doubt, this place rocks.




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I've had my macbook plugged in for most of 2 1/2 years and it hasn't exploded yet. It also still gets over 2 hours of use per charge, which is pretty close to what it got originally. So I wouldn't worry about leaving it charged. Worst case scenario, you'll need a new battery somewhere down the line that'll cost $150 or so.


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I have a MacBook Pro at work that's plugged in all the time and the little 12 inch I'm on right now is always plugged in, too. Nothing terrible has happened to either. My guess is that the batteries will last until the end of their float life and that's that.


We replace a LOT of the magnetic-plug chargers at work. They're not the greatest design in the world (Which is galling. We don't go through Dell chargers like popcorn. Apple needs to make their chargers a little less pretty and a lot more sturdy.) But there's nothing to worry about. The failures are mechanical. The little square connectors simply part from too much use/abuse. If you keep your machine always plugged in, that's not a factor. (And I suspect that using one's own money to buy the machine has some sort of mysterious effect that minimizes cord-yanking damage. Just speculating, mind you :-)




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Hello Chris,


In order to reply to your question I can base myself on what I practically experienced:


I had 2 laptops (an Acer and a HP) that had battery going down to zero performance (and I really mean zero, so that would give energy only for 4-5 seconds) after 6-8 months of constant plug-in use.

My wife's ibook is 6 years old, she used it always alternating days of AC plug with days of battery use, and it still lasts a bit more than 2 hours.


Then, besides laptops, also other devices like cellphones (also using Li-Ion batteries) have the same behavior: I have an old sony ericsson from 6ys ago (I guess I bought it when my wife bought her ibook :) ), on which I almost always make complete charge/discharge battery cycles, and still now the battery lasts a lot.


It must be also said that, by what I read from other posts, it seems like macs seem to manage the battery recharge a bit better than normal laptops, and maybe they have been designed in order to preserve the battery as longer as possible even if constantly plugged.


However I still believe that a complete cycle of discharge / charge once a while is only beneficial to the batteries, and the "physiological" calendar life of a battery is much longer than would be if damaged by the constant full power charge (take a look at my examples).





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If you search the Apple.com support site, there is a guide to getting the longest life out of the battery. As far as I remember, they recommend discharging and recharging fully once in a while to keep it in good condition. This is what I've always followed with my Powerbook and three years in the battery seems to hold the same charge as when new.


If you're bothered or if this is inconvenient, you could always run it down to half way (which Apple recommend when stored) and try using the Macbook without the battery in place. No idea if this would work or not. Used to work with my Powerbook 100 but then they supplied a false box to fill the hole.


If a battery or power supply overheats, there is a serious fault, however long it has been plugged in.


P.S. The PB 100 is still going strong but after more than 10 years the non-Lithium battery is no more.


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"If you're bothered or if this is inconvenient, you could always run it down to half way (which Apple recommend when stored) and try using the Macbook without the battery in place. No idea if this would work or not."


That's what I do. It works fine. I leave all my laptop batteries out in fact, both PC and Mac. Once a month or so I charge them up and run them down, then recharge and remove. Sometimes I use them a wee bit before removal to get them off max charge.


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Despite the claims from manufacturers laptop batteries are often a source of problems and recently class action lawsuits.


Apple have a reasonable track record but have suufered from similar problems to Dell and HP with Sony manufactured Lithuium batteries that overheated. There were several software patches released in 2005/6 to deal with prematue battery failure and poor charge retention.


The first generation Macbook Pro suffers from general overheating and this can have an adverse affect on the battery. The only problem I have found has been with the beautifully designed magsafe charging cable that frayed and sparked. I'm on my second battery but this one is doing fine and holding a charge for 2.5 hours.


My HP laptop is just dreadfull - getting through a battery every 6 months. This is probably the fault of the docking station but given the generally appaling build quality of the rest of the laptop I wouldn't want stake my life on that.


Apple do say that their charger will not overcharge the battery but I find that my unit still gets hot to the touch.


The MBP batteries do look gorgeous though all that aulminium look exterior....hhhhhmmmmm


yours, fully charged, tog




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