Preserving the battery life

Philly

macrumors member
Original poster
May 21, 2007
57
0
UK
Hi,

I just bought a new macbook pro (an upgrade from my very old G4) and I want to know whats happening to the battery if I keep the thing plugged in to the mains on full charge.

Or, to put it another way, when I'm in "the office" should I keep it plugged in, or use it on the battery once it's full?

Thanks,


Philly
 

GGJstudios

macrumors Westmere
May 16, 2008
44,419
759
Or, to put it another way, when I'm in "the office" should I keep it plugged in, or use it on the battery once it's full?
Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug at any time, regardless of the charged percentage. Just make sure you don't run on AC power all the time, as your battery needs to be used regularly to stay healthy. This should answer most, if not all, of your battery/charging questions:
 

Philly

macrumors member
Original poster
May 21, 2007
57
0
UK
Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug at any time, regardless of the charged percentage. Just make sure you don't run on AC power all the time, as your battery needs to be used regularly to stay healthy. This should answer most, if not all, of your battery/charging questions:




GG....thanks.


Miles....rubbish answer. Wanting to maintain a healthy battery is not a pointless concern.
 

miles01110

macrumors Core
Jul 24, 2006
19,269
30
The Ivory Tower (I'm not coming down)
Miles....rubbish answer. Wanting to maintain a healthy battery is not a pointless concern.
Yes it is, for a couple of reasons.

1) Batteries can be replaced. Time cannot.
2) Any "battery-saving measures" you take are not measurable in the end. Your battery does not have a cutoff date or a rating that you'll be able to say you "extended" as a result of your efforts.
3) All batteries die in the first place.

It's unfortunate that common sense doesn't prevail more often in battery discussions.
 

Roman2K~

macrumors 6502a
Mar 11, 2011
552
16
Does the battery (or OS) of the rMBP behave like that of the 3rd gen. iPad?

From "Apple: iPad Battery Nothing to Get Charged Up About":
Apple does, in fact, display the iPad (and iPhone and iPod Touch) as 100 percent charged just before a device reaches a completely charged state. At that point, it will continue charging to 100 percent, then discharge a bit and charge back up to 100 percent, repeating that process until the device is unplugged.
[...]
“That circuitry is designed so you can keep your device plugged in as long as you would like,” Tchao said. “It’s a great feature that’s always been in iOS.”
@miles01110
1) Batteries can be replaced. Time cannot.
Over the years, I've come to the same conclusion... However, if the answer to the question above is "yes", this would bring full peace of mind.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,419
759
Does the battery (or OS) of the rMBP behave like that of the 3rd gen. iPad?
Apple does, in fact, display the iPad (and iPhone and iPod Touch) as 100 percent charged just before a device reaches a completely charged state. At that point, it will continue charging to 100 percent, then discharge a bit and charge back up to 100 percent, repeating that process until the device is unplugged.
No, Mac batteries do not function in that way. From the following link, which is included in the CHARGING section of the Battery FAQ:
Intel-based computers may stop charging between 93 and 99 percent.

This is normal. The batteries used in these computers are designed to avoid short discharge/charge cycles in order to prolong the overall life of the battery.

When setting the Mac OS X battery status menu bar icon to display charge state by percentage, you may notice that the reported charge stays between 93 or 95 percent and 99 percent.

The adapter will not charge the battery to 100% automatically if it will add additional wear to the battery.
 

Roman2K~

macrumors 6502a
Mar 11, 2011
552
16
@GGJstudios
Thanks. This article does explain how wear is avoided by not charging to 100% (not too quickly, at least). It doesn't specify if the rMBP handles prolonged use on AC any differently than other MBPs, so chances are it's handled the same: we still have to run on battery from time to time.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,419
759
@GGJstudios
Thanks. This article does explain how wear is avoided by not charging to 100% (not too quickly, at least). It doesn't specify if the rMBP handles prolonged use on AC any differently than other MBPs, so chances are it's handled the same: we still have to run on battery from time to time.
The Mac notebook battery info applies to all notebooks, including the rMBP. It's different than the battery information for iPhones/iPads/iPods.