Recharge battery

GtrDude

macrumors 6502
Original poster
Apr 17, 2011
459
484
I have a new MacBook Air and wanted to know if there are any rules having to do with recharging its battery, both generally and these three in particular:

1. Do I have to fully deplete it before I start recharging?
2. Is it bad for the battery if I start charging it at say 2% left and then have to unplug and stop charging at about 40% and then continue again later with the rest?
3. Should I leave it plugged in for a while after it reaches 100% charge?

Thanks
 

GtrDude

macrumors 6502
Original poster
Apr 17, 2011
459
484
Look like excellent articles.
Lots of good reading.

Thanks
 

GGJstudios

macrumors Westmere
May 16, 2008
44,421
770
I have a new MacBook Air and wanted to know if there are any rules having to do with recharging its battery, both generally and these three in particular:

1. Do I have to fully deplete it before I start recharging?
2. Is it bad for the battery if I start charging it at say 2% left and then have to unplug and stop charging at about 40% and then continue again later with the rest?
3. Should I leave it plugged in for a while after it reaches 100% charge
Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug any time you need to, regardless of the charged percentage, and you never need to completely drain your battery.
The link below should answer most, if not all, of your battery/charging questions, including tips for maximizing battery performance. If you haven’t already done so, I highly recommend you take the time to read it.
 

motrek

macrumors 68020
Sep 14, 2012
2,428
150
Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug any time you need to, regardless of the charged percentage, and you never need to completely drain your battery.
The link below should answer most, if not all, of your battery/charging questions, including tips for maximizing battery performance. If you haven’t already done so, I highly recommend you take the time to read it.
Agree, basically, don't worry about it and plug in your laptop whenever you can. There's never a reason not to have it plugged in.

That being said, I was surprised a while ago when somebody told me that Apple recommended that you charge-cycle a battery once per month (i.e., run on battery power until it gets low an then charge it back up again). I thought that couldn't possibly be true but it does say to do that somewhere on Apple's web site. Now I can't find it anymore. Maybe they removed it.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,421
770
There's never a reason not to have it plugged in.
Of course there is! When there is no electric outlet available! :D
That being said, I was surprised a while ago when somebody told me that Apple recommended that you charge-cycle a battery once per month (i.e., run on battery power until it gets low an then charge it back up again). I thought that couldn't possibly be true but it does say to do that somewhere on Apple's web site. Now I can't find it anymore. Maybe they removed it.
Apple did, indeed have a recommendation about that on their site until recently. However, it wasn't a recommendation to drain the battery low and recharge. It was to put a cycle on the battery, which can be accomplished by draining to 50% and recharging twice, or draining it to 75% and recharging 4 times, etc. The idea is simply not to leave it exclusively on battery, as batteries should be exercised to remain healthy.
 

Malligator

macrumors member
Mar 31, 2011
44
0
I charge my new MBA just like my iPad and iPhone. If I've used it for any significant period during the day I just plug it in when I go to bed and unplug it in the morning. It's not my work computer so I never run it really low in one day's use. I don't even carry my charging cable when I leave the house with it.

Like others said above just plug it in when you can and don't when you can't. I look at it this way...the battery is rated for 1000 cycles to 80%. That means you can use it to 0% every single day and charge it to 100% every single night for ~2.5 years and the battery will still hold 80% of it's original charge.

In addition, Apple will replace the battery for a nominal charge (I've heard $125, but don't quote me).

All-in-all it's just not something to be OCD about...even though I know a lot of us are. I've actually stopped being OCD about battery charging and started being OCD about storage. With only 128GB I constantly monitor and delete every single byte of unnecessary data on my flash drive. :)
 

GtrDude

macrumors 6502
Original poster
Apr 17, 2011
459
484
Thank you for your fantastic replies and directly answering my question.

Just one more thing that your answers have brought up.

If the battery is down to 50% when I charge it to 100% will that be registered as one cycle in your System Report?

If so wouldn't it make sense to always go pretty low before recharging as many people ask, in re-sale, how many battery recycles there are on the laptop?

Thanks
 

joshlalonde

macrumors 6502
Jul 12, 2014
422
0
Canada
I have a new MacBook Air and wanted to know if there are any rules having to do with recharging its battery, both generally and these three in particular:

1. Do I have to fully deplete it before I start recharging?
2. Is it bad for the battery if I start charging it at say 2% left and then have to unplug and stop charging at about 40% and then continue again later with the rest?
3. Should I leave it plugged in for a while after it reaches 100% charge?

Thanks
To answer your questions in exact order, just for clarification:
1. No. But you should do so every so often (say 1-2 weeks)
2. No. It's perfectly fine.
3. Doesn't matter, as long as you don't leave it plugged in constantly; even if you do leave it plugged in all the time, as long as you deplete the battery every so often as aforementioned, you'll be golden.

According to Apple, "A charge cycle means using all of the battery’s power, but that doesn’t necessarily mean a single charge."

My cycle count is 35. I've had this laptop for two months
 

GGJstudios

macrumors Westmere
May 16, 2008
44,421
770
If the battery is down to 50% when I charge it to 100% will that be registered as one cycle in your System Report?
No. Read the WHAT IS A CYCLE? section of the Apple Notebook Battery FAQ that I linked in post #4.
To answer your questions in exact order, just for clarification:
1. No. But you should do so every so often (say 1-2 weeks)
No, you should not fully deplete the battery. Read the Battery FAQ for more information.
 

motrek

macrumors 68020
Sep 14, 2012
2,428
150
...
No, you should not fully deplete the battery. Read the Battery FAQ for more information.
Well, the FAQ says don't deplete the battery and then store the laptop for a long time, because the battery might fully discharge while in storage and Li-ion batteries can't be recharged after they've been fully discharged. (When your laptop says there's 0% charge left, there's actually a fairly significant amount of charge left, to give you a buffer so they battery doesn't get ruined before you can get to a power outlet.)

So I'd say running your laptop down to a few percent is fine as long as you charge it back up within a reasonable amount of time.

There's certainly no reason to run the laptop down and then charge it back up every 1-2 weeks.

Again, just plug the laptop in whenever it's convenient. You're not going to add any extra "cycles" to the battery by doing this, and there's basically minimal/no reason to add wear to the battery if you don't have to... adding wear meaning using the battery when you could just as easily connect the charger.
 

Newtons Apple

Suspended
Mar 12, 2014
22,759
15,219
Jacksonville, Florida
Thanks Josh. That took care of that.

:)
The main thing is to not obcess about your battery and how to charge it. Just plug it in overnight if it is getting low and it will be ready in the morning. Everyonce in a while you can run it down if it make you feel better, I seldom do. I only need to charge my Air a couple times a week.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,421
770
Well, the FAQ says don't deplete the battery and then store the laptop for a long time, because the battery might fully discharge while in storage and Li-ion batteries can't be recharged after they've been fully discharged.
There are separate instructions for storing, which is to leave about a 50% charge when storing for 6 months or more. That's not what's being discussed here. We're talking about regular use of a Mac.
So I'd say running your laptop down to a few percent is fine as long as you charge it back up within a reasonable amount of time.
If you need to use your Mac and there's no outlet available, running so long that the battery drains and your Mac shuts off won't damage the battery, but it's not something you should do intentionally when you can plug it in.
There's certainly no reason to run the laptop down and then charge it back up every 1-2 weeks.

Again, just plug the laptop in whenever it's convenient. You're not going to add any extra "cycles" to the battery by doing this, and there's basically minimal/no reason to add wear to the battery if you don't have to... adding wear meaning using the battery when you could just as easily connect the charger.
Exactly!
 

motrek

macrumors 68020
Sep 14, 2012
2,428
150
The main thing is to not obcess about your battery and how to charge it. Just plug it in overnight if it is getting low and it will be ready in the morning. Everyonce in a while you can run it down if it make you feel better, I seldom do. I only need to charge my Air a couple times a week.
Or just plug it in whenever it's convenient, not just when it's getting low. There's really no reason not to.

I had a 2010 MBA which was plugged in almost all the time. Probably had ~150 charge cycles on it after 4 years. Battery capacity was still at 90% of the factory original amount.
 

JackieInCo

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Jul 18, 2013
5,178
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Colorado
Every MacBook that I have owned since 2008, I have ruined the battery simply from not using it. Batteries need to be used and will get ruined if they aren't. Use them frequently, not just once or twice a month but as often as you can.

The last batter that I ruined was in a 2010 white MB and from never using the battery, it swelled which eventually pushed up through the trackpad cracking the palm rests on each side of the battery causing the trackpad to lift up from the case about an once. The track pad was ruined and obviously the case. Battery capacity was still al 90% and it still swelled so battery capacity means nothing if it doesn't get used. The black MB battery capacity was at 96% when it swelled.

I also ruined the battery in a 2008 black MB, and two MacBook Pros. I have since bought a Mac Mini and now don't have to worry about batteries. I eventually want to get another MBP but without a doubt, the battery will get ruined from non use as all the others.
 

motrek

macrumors 68020
Sep 14, 2012
2,428
150
Every MacBook that I have owned since 2008, I have ruined the battery simply from not using it. Batteries need to be used and will get ruined if they aren't. Use them frequently, not just once or twice a month but as often as you can.

The last batter that I ruined was in a 2010 white MB and from never using the battery, it swelled which eventually pushed up through the trackpad cracking the palm rests on each side of the battery causing the trackpad to lift up from the case about an once.
...
Sorry but this is a bunch of nonsense.

The mechanism of battery swelling is well understood. It's a buildup of gasses within the battery caused by a chemical reaction that's most often triggered by heat.

It has nothing to do with whether or not you're using the battery. In fact, if you use the battery, it will get warmer and thus be MORE likely to swell, not less. (Not to say that this is common, just more likely.)

The fact that your laptop batteries have ALL swollen almost certainly means your laptops are getting too hot. Not necessarily when you're using them. Do you leave your laptops in the car on hot days? Do you use them in intense, direct sunlight? Do you put them on or near your heaters?

Could be almost anything. But one thing is for sure, I am never ever letting you borrow one of my laptops.
 

JackieInCo

Suspended
Jul 18, 2013
5,178
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Colorado
Sorry but this is a bunch of nonsense.

The mechanism of battery swelling is well understood. It's a buildup of gasses within the battery caused by a chemical reaction that's most often triggered by heat.

It has nothing to do with whether or not you're using the battery. In fact, if you use the battery, it will get warmer and thus be MORE likely to swell, not less. (Not to say that this is common, just more likely.)

The fact that your laptop batteries have ALL swollen almost certainly means your laptops are getting too hot. Not necessarily when you're using them. Do you leave your laptops in the car on hot days? Do you use them in intense, direct sunlight? Do you put them on or near your heaters?

Could be almost anything. But one thing is for sure, I am never ever letting you borrow one of my laptops.
Do some research to find out why batteries swell. It's not from getting hot. These were all just used to watch movies and TV shows in iTunes.

Again, none of these ever left the house and they were very rarely used on battery power which is why all the batteries went bad. The first was a 2008 MBP. Sold it a year after purchase and the buyer told me the battery wouldn't last an hour. I had no idea this happened because well, I never used it on battery power.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,421
770
Every MacBook that I have owned since 2008, I have ruined the battery simply from not using it. Batteries need to be used and will get ruined if they aren't. Use them frequently, not just once or twice a month but as often as you can.

The last batter that I ruined was in a 2010 white MB and from never using the battery, it swelled which eventually pushed up through the trackpad cracking the palm rests on each side of the battery causing the trackpad to lift up from the case about an once. The track pad was ruined and obviously the case. Battery capacity was still al 90% and it still swelled so battery capacity means nothing if it doesn't get used. The black MB battery capacity was at 96% when it swelled.
Batteries don't swell from lack of use. Many will swell near the end of their useful life, regardless of how the battery was used. Some swell with plenty of life left in them, due to manufacturing defect.

You won't kill a battery by not using it, but you may shorten its lifespan. Yes, it's a good idea to run on battery power regularly, but it has nothing to do with batteries swelling.
Sold it a year after purchase and the buyer told me the battery wouldn't last an hour. I had no idea this happened because well, I never used it on battery power.
If it swelled within the first year, you could have returned it for free replacement under warranty. Also, you can check the battery health without actually running on battery, to see if its maximum capacity has diminished. If it dropped below 80% health before the target cycles were completed, it may have qualified for warranty replacement.
 

JackieInCo

Suspended
Jul 18, 2013
5,178
1,598
Colorado
Batteries don't swell from lack of use. Many will swell near the end of their useful life, regardless of how the battery was used. Some swell with plenty of life left in them, due to manufacturing defect.

You won't kill a battery by not using it, but you may shorten its lifespan. Yes, it's a good idea to run on battery power regularly, but it has nothing to do with batteries swelling.
The swelling was just an added defect but the fact is, the batteries went bad from not using them.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,421
770
The swelling was just an added defect but the fact is, the batteries went bad from not using them.
Batteries don't "go bad" from lack of use. Their lifespan can be shortened if not exercised, but that doesn't cause swelling or battery failure. Apple has even removed from their website their recommendation about putting at least one cycle per month on a battery.
 

motrek

macrumors 68020
Sep 14, 2012
2,428
150
The swelling was just an added defect but the fact is, the batteries went bad from not using them.
You told me to "do some research" but where is your research? All you're telling us is that your laptop batteries have gone bad and you didn't use them (the batteries)... yes, there is a CORRELATION there but it's not CAUSATION. This is extremely simple logic.

As a counterpoint, I have been through four MacBooks and none of them have had swollen batteries and I leave my laptops plugged in 99% of the time.

Heat is the most common cause of battery swelling--whether it's a one-time event or it happens after many thermal cycles of discharging and recharging the battery. Instead of writing posts full of faulty logic on this board, you might do yourself good to sit and think of other reasons why ALL of your laptop batteries have self-destructed whereas this happens to almost nobody else.
 
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