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Battery preservation and 'Desktop Mode'

In The correct way to use your MacBook's battery I wrote that Apple techs recommend that you regularly charge and run down the battery in its notebooks for maximum battery performance and lifespan.In other words – don't leave your MacBook plugged in all the time.

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In The correct way to use your MacBook's battery I wrote that Apple techs recommend that you regularly charge and run down the battery in its notebooks for maximum battery performance and lifespan.

In other words – don't leave your MacBook plugged in all the time. In Apple's eyes having more charge cycles is better than having less, in fact, it can even deny a battery warranty claim if your battery has less than 75 charge cycles.

That post resonated with several readers that emailed me to complain that Apple should handle the whole battery charge/discharge process in software, rather than relying on users to remember to do it.

Bruce Kieffer wrote:

I'm listening to PowerPage Podcast Episode 114 and the discussion on batteries. I must say it's a disappointment that the Mac OS isn't smart enough to deal with all power situations. Why should I have to mess with cycling my battery? Why can't the OS know my power habits and take care of conditioning the battery accordingly? I have a PowerBook G4 and I keep it plugged in 24/7. I think in that case the OS should be smart enough to cycle my battery for me.

While I agree with Bruce, the devil as they say, is in the details. After all, how would Apple implement such a technique that keeps the battery optimized while ensuring that you're not left without charge at the worst possible moment in time.

Apple would have to run the battery down (via software) despite the fact that you have it plugged in. That would invite a whole host of problems with users that need to spontaneously grab their machine only to discover that the battery is completely dead.

My suggestion is that Apple implement a "Desktop Mode" in Mac OS X that would prompt you, saying "I noticed that you haven't unplugged your AC power connection in 30 days. Would you like me to go into Desktop Mode? More info... Yes/No"

It could explain that Desktop Mode power cycles the battery "in order to maximize its useful life" or something like that and warn users to make sure to disable Desktop Mode (in Energy Saver > Advanced?) at least 8 hours before running off battery.

Bruce responds:

The best solution would be batteries that don't need to be cycled. Until then, I like your "Desktop Mode" idea, but it too has its problems. Most often I know in advance when I need my computer on the road. But if I have to take it out on a last minute notice, I could be in trouble if the battery was near the end of a discharge cycle. Maybe the Apple folks could set it up to discharge during down times. Say schedule it for midnight to 6 am. As it is now, I will continue with it plugged in all the time since anything else is too much work relative to any benefit I might get in extending the battery life.

What's your solution? Do you regularly run down your MacBook battery or are you a "leave it plugged in all the time" type of person?