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Battery guage... seriously

tunerX

tunerX

Suspended
Original poster
Nov 5, 2009
355
839
So I have noticed that after owning my MBP for two weeks that no matter how long I leave it plugged in the percentage indicator keeps dropping.

On the first day it was at 100. Then over the course of a week it dropped to 99. Now it is at 97.

I am now going through the calibration steps that say to run it down until it shuts down, then leave it in that state for 5 or more hours, then charge it until the little light turns green. I have never done this on any rechargeable device I have owned. But I figure that i need to do this since it says 97 instead of 100 percent.
 
Erasmus

Erasmus

macrumors 68030
Jun 22, 2006
2,756
298
Australia
Your computer will not top up the battery until it drops to below 95%. It does this to reduce charging stress on the battery, extending its life.

Furthermore, under heavy load, your computer will drain slightly more power than the mains power supply can provide. The extra power comes from the battery.

Therefore your battery charge will very slowly drop over time until it falls below 95%, before fully recharging.

(Waits for GGJstudios' "This will answer some, if not all of your battery questions" post...)
 
Last edited:
shardey

shardey

macrumors 6502a
Jan 28, 2010
710
45
Colorado
If you are going to worry about anything, worry about how many charge cycles you have on your battery, and what the full charge capacity (in mAh) is.
 
T

thundersteele

macrumors 68030
Oct 19, 2011
2,984
9
Switzerland
If the battery is between about 95% and 100%, it does not get charged. This is to avoid short charge cycles that are bad for the long term performance of the battery.

If for some reason you want to see it fully charged, disconnect, let it drop to 90%, and reconnect it.

As to why the battery might loose charge while connected:
Under very heavy load, the MBPs consume slightly more power than the adapter can provide, and very slowly discharge the battery.
 
tunerX

tunerX

Suspended
Original poster
Nov 5, 2009
355
839
thundersteele said:
If the battery is between about 95% and 100%, it does not get charged. This is to avoid short charge cycles that are bad for the long term performance of the battery.

If for some reason you want to see it fully charged, disconnect, let it drop to 90%, and reconnect it.

As to why the battery might loose charge while connected:
Under very heavy load, the MBPs consume slightly more power than the adapter can provide, and very slowly discharge the battery.
Click to expand...

OK, so was I supposed to do the battery conditioning?
 
Last edited by a moderator:
U

/user/me

macrumors 6502
Feb 28, 2011
496
0
If it's anything like the iPhone, the battery can't actually charge to 100%, but it's rather displayed as 100% for the user to feel satisfied...
 
GGJstudios

GGJstudios

macrumors Westmere
May 16, 2008
44,545
943
tunerX said:
So I have noticed that after owning my MBP for two weeks that no matter how long I leave it plugged in the percentage indicator keeps dropping.

On the first day it was at 100. Then over the course of a week it dropped to 99. Now it is at 97.

I am now going through the calibration steps that say to run it down until it shuts down, then leave it in that state for 5 or more hours, then charge it until the little light turns green. I have never done this on any rechargeable device I have owned. But I figure that i need to do this since it says 97 instead of 100 percent.
Click to expand...
As others have stated, it's possible that during periods of high demand, your Mac draws power from both the AC adapter and the battery, causing the charge to drop. Also, batteries are prevented from charging between 93% and 99%, to avoid short charge/discharge cycles. It's all quite normal. Finally, the built-in batteries in the newer Mac unibody notebooks come pre-calibrated and do not require regular calibration like the removable batteries.

This should answer most, if not all, of your battery questions:
 
GGJstudios

GGJstudios

macrumors Westmere
May 16, 2008
44,545
943
Comeagain? said:
Why don't you share you Text Edit files, and then you won't be the only person to post it!
Click to expand...
I don't use TextEdit, but you can copy any of my posts. Just click Quote, then copy the text, including links. I'm not the only one, as many have quoted my posts to answer questions, most notably simsaladimbamba.
 
Comeagain?

Comeagain?

macrumors 68020
Feb 17, 2011
2,190
46
Spokane, WA
GGJstudios said:
I don't use TextEdit, but you can copy any of my posts. Just click Quote, then copy the text, including links. I'm not the only one, as many have quoted my posts to answer questions, most notably simsaladimbamba.
Click to expand...

GGJstudios said:
Actually, I use the old copy/paste method from TextEdit files. I should take a look at TextExpander, since you've recommended it before. I've just been too busy (lazy) to research it.
Click to expand...

:confused:
 
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