Best for battery life...plugged in constantly or no?

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Just got my new MBP 17" i5, 4GB RAM, OS 10.6.4 last week. Trying my best to relearn the Mac stuff again.

I had bad luck with PC laptop batteries not lasting long so what is the best way to care for the life of my battery?

1. Is it better to keep your laptop plugged in constantly while in use and when not in use?

or

2. Is it better to only have it plugged in while being charged but when the battery is fully charged, unplug it while using laptop and while it's asleep.

The 2nd one will obviously increase the number of charge cycles drastically but I wasn't sure what the effect was of leaving it plugged in all the time. I've been leaving it plugged in while in use and when not in use but now I'm worried that maybe this isn't the best thing for the battery.

Thanks!
 

CrimsonRequiem


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When I'm at home I have it plugged in. When I have to go somewhere obviously it's not plugged in. I usually use it until it's around 30% or lower then charge it.

Had this MB for 2 years and the battery health is at 95%.
 
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Searching will find you a lot of information already discussed on this topic.

Also see this:
Apple - Batteries
 

pigoo3

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Yes...this question has been asked & discussed MANY MANY times!!! Please use the search function.:)

- Nick
 
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I actually did use the search function and typed in battery care. What came up was everything but what I was looking for so I posed the question here in the switcher's forum since I am a "switcher" so to speak.

I googled it as well and basically seems like everyone has a different opinion on how best to deal with it (also depending on when article was written). Plus, I'm not up to speed on the different types of Macs and whether or not Apple uses different types of batteries for certain models.

One article I read claims that a "charge cycle" takes place when you run on battery power for however long and then plug it in to charge. Even if you only use 20% of the battery power during that time and then plug it in, it still counts as one cycle.

To completely contradict that article, another writer states that the computer counts one full cycle as a battery discharge of 80% or more no matter how many times you plug and unplug the laptop during that time. So if you unplug and use your battery 20%, plug it back in to recharge it back up to 100%, then unplug again using battery down to 60% before plugging back in that the laptop will actually keep track and add 40% plus 20% for a total of 60% of one full cycle thereby giving you at least another 20% of battery life usage before the computer logs that as one full charge.

I'll just keep it plugged in and fully discharge the battery once a week to keep the battery juices going as Apple recommends. Sometimes it's just nice to be involved in a discussion of something I lack knowledge of as you can see that sometimes the search function and research comes up with confusing information.
 

pigoo3

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I actually did use the search function and typed in battery care. What came up was everything but what I was looking for so I posed the question here in the switcher's forum since I am a "switcher" so to speak.

Whenever doing an internet or forum search...sometimes you have to try multiple terms or combinations of terms until you find what you need. You can't just try one search...or search term...and then give up.

Have you tried these search terms:

- battery
- battery life
- battery time
- runtime
- battery runtime
- battery health
- etc. etc.

I tried "battery life"...and got lots of "hits".:) Sometimes after you have success using one term...and read the threads...you then become aware of more terms to use to do additional searches.

HTH,

- Nick
 
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Short answer: unplug it with some frequency to get the best battery life.

NOTE: I had a Late 2008 2.53Ghz MBP that was plugged in constantly for about 1.5 years. The battery lasted an honest hour and a half with about 20% brightness, Wireless N browsing and email, and iTunes music in the background. I spent a week of evenings after work, before a business trip, unplugging it and running off the battery until the warning popped up. After 7 or 8 days I was seeing about 2 and a half hours of run time. Point being: sedentary batteries lose efficiency, but they can be brought up to speed fairly quickly in my experience.
 
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I googled it as well and basically seems like everyone has a different opinion on how best to deal with it (also depending on when article was written).

Read the site I linked above, and follow Apple's advice. They know best how to treat their batteries.
 
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chas_m

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All I can offer is my anecdotal evidence. I have a 2007 BlackBook that has always spent 99% of its time plugged in. On the the rare occasions that I do run it on battery, it rarely gets below 90% before I am back home and its charging again. Every once in a great while (1-2 times a year), I actually let it run down to reserve power.

This battery (which may or may not be an anomoly) still runs with 95% health and gives me as much time on battery as it always has, around 3 hours depending on what I'm doing.
 
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Thanks for the link shweb. I did check it out.

chas_m, that's actually pretty amazing considering the age. Thanks for the input. Hope I have the same experience with mine.
 
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I believe the best practice is to fully drain the battery and the recharge at least once a month. I have a MacBook I bought in February 2008 and it still has a 88% of it's original charge. That's after using it on battery power almost every day since I got it.

You are going to find that the batteries in the Macs are far from the cheapo ones used in most other laptops.
 
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MacInWin

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This article explains the chemistry behind Lithium Ion batteries clearly. It's a good read. Note in paragraph four it refers to the "digital memory" issue that gives the appearance of reduced capacity in batteries that are kept topped up. Bottom line: the appearance of rejuvenated batteries when fully discharged is not a rejuvenation of the battery but a recalibration of the fuel gauge. They recommend a full discharge every 30 cycles, just to recalibrate the gauge.
 
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I've read so much on batteries over the years that I'm not sure if many people on the net really know about them, but everybody seems to have their own idea. I have gathered that batteries have a finite life in terms of charge cycles, but also you have to exercise them some and it helps to do it a certain way.

I've read that with Litium Ion batteries if you run the battery down to 50% and recharge it, that counts as 1/2 cycle, if you run it down to 0 and recharge it that counts as a full cycle. I've also read that the calibration can get out of whack and the computer will report limited life when the battery might have more life in it. I saw a procedure for PC's where you disable the warnings and let the battery run down all the way, then the PC knows at what point the battery is really out.

I've also noticed that batteries can vary a lot from one to another, no matter what the manufacturer is. I've heard of lots of people with iphones with dead batteries, and I've seen macbooks on craigslist with dead batteries, so Apple isn't immune. Three people in my family have Dell notebooks- one battery lasted 1 year, 1 battery lasted 2 years, the third one is still working after 5 years. I went online to buy a new battery for my mother. I searched lots of sellers, and on Amazon you can read reviews on many of the sellers. Every seller had a lot of customers that had good luck with their products, and a few who said their batteries were crap. So all that leads me to believe that whoever is actually making the batteries (Apple doesn't make their own batteries for instance) either has quality control problems or that is just the nature of Lithium Ion battery manufacturing.

Sorry for the long winded response but I believe in exercising a battery some. I use my notebooks at home on the dining table quite a bit, and what I do is plug the machine in for two or three days while using it, then the fourth day I run it on the battery.
 
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chas_m

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This article explains the chemistry behind Lithium Ion batteries clearly. It's a good read. Note in paragraph four it refers to the "digital memory" issue that gives the appearance of reduced capacity in batteries that are kept topped up. Bottom line: the appearance of rejuvenated batteries when fully discharged is not a rejuvenation of the battery but a recalibration of the fuel gauge. They recommend a full discharge every 30 cycles, just to recalibrate the gauge.

Ah, this may explain my exceptional "luck" with my battery.

Since my battery spends so much of its time plugged in, I only have 103 cycles after 41 months, so that once per year or so I let it drain seems to work out to about every 30 cycles or so! :)

Serendipity!
 

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