Currently Being ModeratedJan 20, 2012 6:50 AM (in response to ccbb133)
I always tell people there are two ways to wear out a battery. Overuse it or underuse it. Having it plugged in will not affect your battery unless you never actually use it under battery power. My MBP is plugged in all day at my office but at home I only use it on battery power. At night I plug it back in. After more than two years my battery health is still well over 80% and I have no complaints about battery life.
Currently Being ModeratedJan 20, 2012 7:18 AM (in response to Andrew Wolczyk)
Thanks, Andrew. I was told by the Apple store employee not to leave it plugged in all the time because it would degrade the battery, so I was thinking of just physically taking the battery out at work while I have it plugged in and then using the battery at night at home. Sounds like it wouldn't make much difference. Thanks for the insight.
Currently Being ModeratedJan 20, 2012 8:28 AM (in response to ccbb133)
You do not save battery life by removing it and keeping unused for a long time, not by keeping charger plugged all the time. A healthy battery should be used normally, by discharging it totally approx. once in a month. Do not keep battery unsed for a long time (weeks, months), you risk of degrading it irreversibly. Note that a battery cannot keep an eternity so, one good day, you must replace it. My oldest battery is the one in a 2004 PowerBook, of course, not the original one, was replaced in 2007, and is still around 75 %.
Currently Being ModeratedJan 20, 2012 8:35 AM (in response to Cattus Thraex)
Yes, sorry, should have clarified that I was thinking of just taking the battery out during the day while plugged in, but still using the battery daily at home. I just recently replaced the original battery after about 3 years, but I am now using the MacBook much more on a daily basis than I was originally. Thanks much.
Currently Being ModeratedJan 20, 2012 8:37 AM (in response to ccbb133)
There’s one problem with running your MacBook with the battery removed. MacBooks and MacBook Pros automatically reduce the processor speed by about half when the battery is removed.
Currently Being ModeratedJan 20, 2012 11:14 AM (in response to ccbb133)
Never, you do not save its life in this way, not is this healthy for your computer. At normale usage, a good battery should keep at least 3 years at over 65 % of its original capacity. If less than a year, it is anyway replaced under warranty conditions, if after 2 years, bad luck. But there were instances when Apple replace bad batteries, and other components, beyond the warranty period if proved that a large percentage had a worse quality than normal.