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still in school

macrumors 6502
Original poster
Feb 21, 2009
270
0
I want to prolong the battery life as long as possible. If I am sitting at my desk with an available ac outlet and my battery is already full. Is it better to run off the ac adapter? Is it harmful?
 

SeanU

macrumors member
Feb 2, 2009
64
0
Apple is pretty good...

I wish Apple gave you more control over charging thresholds. Li-ion batteries do not like to be fully discharged. The only reason Apple (and others) recommend a full discharge is so that their battery meter is more accurate.

Mac's won't charge the battery if it is just a few ticks under 100% which is a good thing. Apple considers a charging cycle to be a full 0 - 100% battery charge... so if your battery drops to 50%, you plug in and charge to 100%, that is 1/2 a cycle.

The 2 best pieces of advice I have gotten about maintaining batter life are
1) When the battery drops to 30% plug it in and charge.
2) When storing the laptop for extended periods, do not charge it fully. Leave it at 50 or 60%.

Other than that, just use your laptop the way you want to. These batteries lose capacity over time, as well as charge cycles. It will need to be replaced someday.

Sean
 

SeaneyC

macrumors member
Jan 27, 2009
32
0
I wish Apple gave you more control over charging thresholds. Li-ion batteries do not like to be fully discharged. The only reason Apple (and others) recommend a full discharge is so that their battery meter is more accurate.

There is no way in a modern device to fully discharge a Li-Ion or Li-Polymer battery, the circuitry between the battery and device prevents this no matter how hard you try.....

Which is why they recommend doing a full discharge every so often.
 

still in school

macrumors 6502
Original poster
Feb 21, 2009
270
0
well since macs won't let you charge a tick over 100%, and if i keep the ac adapter in, wouldn't that mean i'll be using pure a/c line and avoiding use of battery at all?
 

Zedsdead185

macrumors 6502
Sep 14, 2006
489
23
UK
Hmmm, i would probably suggest unpugging it when you need. I remember being in the same boat as you just over 12 months ago with my new at the time macbook pro. Well, most of the time i use it plugged in, occasionally unplugged, and i think i may have ruined the battery. I've just calibrated my battery again today and coconut battery is telling me the max capacity it can now hold is only 36% of what it used to be :(
 

still in school

macrumors 6502
Original poster
Feb 21, 2009
270
0
Hmmm, i would probably suggest unpugging it when you need. I remember being in the same boat as you just over 12 months ago with my new at the time macbook pro. Well, most of the time i use it plugged in, occasionally unplugged, and i think i may have ruined the battery. I've just calibrated my battery again today and coconut battery is telling me the max capacity it can now hold is only 36% of what it used to be :(

wow, thanks for your input!
 

manhattanboy

macrumors 6502a
Jan 25, 2007
960
370
In ur GF's bed, Oh no he didn't!
I wish Apple gave you more control over charging thresholds. Li-ion batteries do not like to be fully discharged. The only reason Apple (and others) recommend a full discharge is so that their battery meter is more accurate.

Mac's won't charge the battery if it is just a few ticks under 100% which is a good thing. Apple considers a charging cycle to be a full 0 - 100% battery charge... so if your battery drops to 50%, you plug in and charge to 100%, that is 1/2 a cycle.

The 2 best pieces of advice I have gotten about maintaining batter life are
1) When the battery drops to 30% plug it in and charge.
2) When storing the laptop for extended periods, do not charge it fully. Leave it at 50 or 60%.

Other than that, just use your laptop the way you want to. These batteries lose capacity over time, as well as charge cycles. It will need to be replaced someday.

Sean

great post, thanks
 

dubhe

macrumors 65816
May 1, 2007
1,304
10
Norwich, UK
Well, most of the time i use it plugged in, occasionally unplugged, and i think i may have ruined the battery. I've just calibrated my battery again today and coconut battery is telling me the max capacity it can now hold is only 36% of what it used to be :(

I bet if you cycle it a few times you'll be back above 50%.

Batteries are funny things, and as one of the earlier poster said, cycling the battery is more about the chip inside telling you an accurate story than the battery actually having more capacity.

Batteries these days are designed to be used a little, then recharged. That is what we should be doing. Once every couple of months, do a cycle, but more to keep a tab on what the chip is telling you. I think the phrase 'condition' is incorrect.
 

GeekAtBirth

macrumors member
Mar 21, 2009
56
0
I wish Apple gave you more control over charging thresholds. Li-ion batteries do not like to be fully discharged. The only reason Apple (and others) recommend a full discharge is so that their battery meter is more accurate.

Mac's won't charge the battery if it is just a few ticks under 100% which is a good thing. Apple considers a charging cycle to be a full 0 - 100% battery charge... so if your battery drops to 50%, you plug in and charge to 100%, that is 1/2 a cycle.

The 2 best pieces of advice I have gotten about maintaining batter life are
1) When the battery drops to 30% plug it in and charge.
2) When storing the laptop for extended periods, do not charge it fully. Leave it at 50 or 60%.

Other than that, just use your laptop the way you want to. These batteries lose capacity over time, as well as charge cycles. It will need to be replaced someday.

Sean
Is it okay if I just cycle it all the time?
 

imax2k2

macrumors regular
Feb 25, 2009
107
9
I just downloaded Coconut battery and I have the full capacity now on 95%, and thats after 2 months of usage, and it shows I have had about 69 cycles, I usually make it go down to 20-30% and recharge somtimes as low as ~4-5%, is this not how I should be using it? Also is it normal to have dipped 5% in 2 months.

Thanks
 

McGilli

macrumors 6502
Nov 11, 2008
380
0
2) When storing the laptop for extended periods, do not charge it fully. Leave it at 50 or 60%.
Sean

I think that applies more to devices that don't eat a lot of battery when they are powered off.

With all other devices that is what I do - but with the MBA - since even when shut down mine uses about 4% battery per day - I prefer to have it topped up when being stored for a long time (usually around 10 days) - otherwise when i turn it on I would be down to like %10-20% battery .... and then looking at a good 7 to 8 hours to charge! (for mine anyways)
 
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