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MacBook Performance Dropping On AC Power


MacBook Performance Dropping On AC Power

Anyone buying a new Aluminium MacBook and hoping to extend the lifespan of the battery by removing it when using the AC adaptor may want to think again. According to testing done by Gearlog, doing so results in a performance drop of some 37 per cent.

This isn't an 'issue' as such, but rather a feature. According to Apple's support section on its site, system performance is dropped when the battery is removed to stop the machine from shutting down if it tries to draw more power than the outlet can provide.

That seems a little strange, really. The ability of the battery to deliver power drops off over time, but MacBooks almost certainly won't detect that change and drop performance in order to prevent potential shutdowns in that situation.

Of course if you're one of what I expect are very few people actually noticing this as an issue, then the simple solution is simply not to remove your battery. Otherwise chalk this up as interesting, but irellevent.





November 24, 2008, 5:46 pm

Got to love Apple's features!

Just like with the MacBook air where no optical drive or ethernet is a "feature" cos its actually made for the wireless world!


November 24, 2008, 5:51 pm

This has always been the case, and there is nothing wrong with it.

Anyone who takes the battery out of their notebook when they run it on the mains is, in my book, a total weirdo anyway.


November 24, 2008, 6:59 pm

@Ben: Why? If the notebook is always used on mains then the battery life will just degrade due to the lack of power cycles.


November 24, 2008, 7:07 pm

@ Ben: since you clearly have no idea what you are talking about (as it was mentioned even in this article why the removal of batteries is necessary in case of stationary laptops) you are certainly with the right company providing such amazing "features".


November 24, 2008, 7:55 pm

i've never removed my battery just to run things on the mains, and i don't know anybody who does: the risk of forgetting and just unplugging it to move it is too much to bear...


November 24, 2008, 9:21 pm

This isn't news - all Intel MacBooks do this. My 2006 1.83GHz MacBook Pro drops the CPUs to 1GHz without the battery installed.

mr dog

November 24, 2008, 9:40 pm

i left the battery out of my old dell insprion 5100 all the time and after three years still got a good hour and a half out of it on the rare ocasions i went totally mobile; enough to watch a full length film on a flight. then i gave the laptop to a friend who always left the battery in and it now lasts for a mighty five minutes before shutting down.

but at least you can run the system without the battery, if i remember correctly a 'feature' of the old G4 iBook was that even if it was plugged in, removal of the battery would kill the power.


November 24, 2008, 10:11 pm

@ Darfuria & Singularity - Notebook batteries have a certain life span from the date of manufacture anyway. There isn't a great deal to gain by removing the battery just because the machine is being used on the mains for a prolonged period. As for stationary notebooks... Apple has a name for those: "iMac". If you must have an Apple 'stationary' notebook, just leave the battery in. Every notebook comes with one anyway, so it's not like it's costing any extra.

@ Singularity - I'm sorry that you feel I "clearly have no idea" what I'm talking about. The feeling, I assure you, is mutual.


November 25, 2008, 12:15 am

@ Ben - nothing to feel sorry about: your comment above just underlines my point. The life span of batteries is measured in charge cycles (as pointed out by Darfuria) and not time; the time given by the manufacturer is an approximation based to the number of typical charge cycles for that time period. Next time perhaps you would want to do some research before commenting on an unfamiliar topic...


November 25, 2008, 1:27 am

@ Singularity - From Wikipedia: A unique drawback of the Li-ion battery is that its service life is dependent upon aging (shelf life). From time of manufacturing, regardless of whether it was charged or the number of charge/discharge cycles, the battery will decline slowly and predictably in "capacity". This means an older battery will not last as long as a new battery due solely to its age, unlike other batteries. http://en.wikipedia.org/wik...


November 25, 2008, 1:52 am

Battery life will degrade regardless due to operating temperatures, but you have a valid point, Ben.

Got to love the "buy a computer then" card, though. No one can ever resist that one.


November 25, 2008, 2:10 am

@ singularity - that's true of older batteries, but the current generation of Lithium ion batteries start to lose maximum charge the moment they come off the production line, I think the average loss in a year if left in a warm environment (like that of an operating laptop) is around 40% of it's potential capacity. If it's removed from the laptop when the laptop is plugged into mains the rate of decay is substantially reduced (enough to give you several more months of good usage) and even more so if the battery is kept in a cool place.

Robert Elliot

November 25, 2008, 2:40 am

Are there really people out there who pull the battery out, so if they want to pick the laptop up and sit on the sofa for a bit they have to put the battery in first?! I suppose it takes all sorts, funny old world etc. etc.

Geoff Richards

November 25, 2008, 2:47 am

@Robert - I think that's more for people like me, who run their notebook on a desktop, plugged into the mains 90% of the time. The theory goes that this is bad for the battery, so having run it plugged in for the whole year, when I jet off to Australia in 2 weeks I don't find that the battery life is barely 2 hours instead of 5 because my cells are shagged.

Honestly, I don't know whether it's true or not and I gave up the practice ages ago. But that's the principle.


November 25, 2008, 4:02 am

@ Gnormie - you are perfectly right, however the high operating temperature (especially in overheating Apple notebooks) significantly reduces battery life over time (especially if your laptop is plugged in most of the time). The best practice to maximize battery life is nonetheless the same: to remove the battery and store it in a cool place. Besides, this – so called – feature has been put in place by Apple with older generation of laptops (and batteries) as well (as pointed out by other comments in this forum) so I thought it to be worthwhile mentioning.

@Ben – why don’t you read the very article you have mentioned to the end, with special attention to how to prolong battery life. But you get points for research...

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