iPhone 6s Plus always plugged in, bad for battery?

mango316

macrumors regular
Original poster
Sep 13, 2014
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Would it be bad for the battery if I always plugged in iPhone 6s Plus even though it reached 100% charged when I'm not using?
 

lamborghini392

macrumors member
Oct 22, 2015
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IIRC once the battery hits 100% while plugged in, the charger inside the phone cuts the current to the battery and the phone will continue to run off the charger's current. I have always left all of my phones charging overnight every night and they never suffered from any problems, so no it's not bad for the battery.
 
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mango316

macrumors regular
Original poster
Sep 13, 2014
111
135
IIRC once the battery hits 100% while plugged in, the charger inside the phone cuts the current to the battery and the phone will continue to run off the charger's current. I have always left all of my phones charging overnight every night and they never suffered from any problems, so no it's not bad for the battery.
Cool, thanks for your input!
 

sunking101

macrumors 604
Sep 19, 2013
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It won't do it any good to leave it constantly connected though, because although the battery has an overcharge failsafe you're still constantly topping it off. It will slowly eat into your charge cycles.
 

darrylcn

macrumors regular
Oct 24, 2015
170
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I leave my phone on the charger all day at work (oddly enough to reduce battery cycles) and as a result of that and charging it each evening it's rarely below 50%. I assumed it had a way to just switch over to USB power once it was topped up, but that periodic top up makes sense. Hopefully I'm not doing harm, there's a lot of battery theories out there as you know.
 

sunking101

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Sep 19, 2013
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I leave my phone on the charger all day at work (oddly enough to reduce battery cycles) and as a result of that and charging it each evening it's rarely below 50%. I assumed it had a way to just switch over to USB power once it was topped up, but that periodic top up makes sense. Hopefully I'm not doing harm, there's a lot of battery theories out there as you know.
It will charge to 100%, stop charging, drop to 99% and then start charging again. This constant cycle won't do any harm as such, but it will reduce the longevity of your battery.

Mind you, so does using it off the mains and then recharging. You can't win really but I would refrain from constantly topping it off.
 

lamborghini392

macrumors member
Oct 22, 2015
89
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The battery "self discharges" like 5% per month. So it won't drop be dropping to 99% overnight while it's plugged in. Apple has a threshold set on this number specifically to prevent the battery from constantly trickle charging (and increasing charge cycles like you said). So if you leave it plugged in for a month then maybe it will have to "top it off" but otherwise the battery neither charges or discharges once it hits 100%.
 

darrylcn

macrumors regular
Oct 24, 2015
170
36
That's what I was hoping - that an 8 hr workday (charged to full after losing some during commute on bus) would mean one top up from ~93% then one or two 99->100%s during the day. I'll be on two year contracts next time I renew (Christmas 6S Plus I hope, may have mentioned that hehe!) so my habits may be moot. My 5 is in fact only 1 year old as I replaced it last year at an Apple store following a swelling battery.
 

sunking101

macrumors 604
Sep 19, 2013
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The battery "self discharges" like 5% per month. So it won't drop be dropping to 99% overnight while it's plugged in. Apple has a threshold set on this number specifically to prevent the battery from constantly trickle charging (and increasing charge cycles like you said). So if you leave it plugged in for a month then maybe it will have to "top it off" but otherwise the battery neither charges or discharges once it hits 100%.
That 5% discharge is if switched off.
 

measel

macrumors regular
Jul 25, 2010
106
27
Kalamazoo, MI
Whenever I get a new iPhone, I like to charge it full then drain it full to 0% at least 4-5 times to help push the longevity. Then I only plug it in at nights. Sometime if I knew the next day I would be home most of day (weekends), I don't plug it in at all. At end, The battery give me more than a day for over a year.
 

lamborghini392

macrumors member
Oct 22, 2015
89
24
That 5% discharge is if switched off.
When the phone is plugged in while at 100% the battery is isolated if you will, and the phone continues to run off the current from the charger, not the battery. So the battery is neither charging or discharging which means it's effectively the same thing as having the phone off. Most charging ICs (iPhones, laptops, samsung phones, high end chargers for li-ion xbox 360 remote batteries, etc) do this to prevent unnecessary wear on the battery.

Sometime if I knew the next day I would be home most of day (weekends), I don't plug it in at all. At end, The battery give me more than a day for over a year.
That's not a bad habit actually. I supposed I stand somewhat corrected. Li-ion batteries last their longest when kept between about 40-80% of their capacity. So storing 100% charge inside one might reduce the lifespan slightly, but whether it's sitting on the charger or just idling at 100% overnight doesn't make a difference.
 

Andres186

macrumors newbie
Oct 21, 2015
26
3
I don't understand... it's called MOBILE phone, so people can use it without a cable. Why should it be always plugged in anyway?!
 

Newtons Apple

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It will charge to 100%, stop charging, drop to 99% and then start charging again. This constant cycle won't do any harm as such, but it will reduce the longevity of your battery.

Mind you, so does using it off the mains and then recharging. You can't win really but I would refrain from constantly topping it off.

It will do no more harm than unplugging and turning it off as the battery will drop even while turned off and will need to be charged. Either way you will be eating up cycles. You are right that is can not be avoided and best to not worry about it.
 

Newtons Apple

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Whenever I get a new iPhone, I like to charge it full then drain it full to 0% at least 4-5 times to help push the longevity. Then I only plug it in at nights. Sometime if I knew the next day I would be home most of day (weekends), I don't plug it in at all. At end, The battery give me more than a day for over a year.
You might like to do this but this does nothing to help you battery but instead eats of 4-5 full cycles.
 
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Newtons Apple

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I don't understand... it's called MOBILE phone, so people can use it without a cable. Why should it be always plugged in anyway?!

For some carrying their phone with them is not needed or required. If you sit at a desk all day or at home and do not need to have you phone on your person.

In these cases the battery would avoid as many cycles by leaving it plugged in while a power source is available. I do the same with my MacBook Pro and mostly use it when the power is available, so to save from having additional cycles on the battery, I plug it in. You should too but it is all up to your.
 
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sunking101

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For some carrying their phone with them is not needed or required. If you sit at a desk all day or at home and do not need to have you phone on your person.

In these cases the battery would avoid as many cycles by leaving it plugged in while a power source is available. I do the same with my MacBook Pro and mostly use it when the power is available, so to save from having additional cycles on the battery, I plug it in. You should too but it is all up to your.
Do we have documented proof that this is indeed what happens? Has anyone checked their battery cycle count and then left their iDevice connected to the mains for a couple of days (whilst using it too) before checking the number of cycles again?
 

sunking101

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I once ran a laptop connected to the mains 24/7 and never used the battery. 18 months later when I did try to use it the battery was shot. It held a charge for 20 mins and ever since then I have charged my laptop, used it on battery power until empty and then charged it again. Almost two years later it still lasts for several hours on battery power.

Based on that experience alone I choose not to leave battery-powered devices connected to the mains for any considerable periods of time. Once charged I disconnect them from the mains supply.
 
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Newtons Apple

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I once ran a laptop connected to the mains 24/7 and never used the battery. 18 months later when I did try to use it the battery was shot. It held a charge for 20 mins and ever since then I have charged my laptop, used it on battery power until empty and then charged it again. Almost two years later it still lasts for several hours on battery power.

Based on that experience alone I choose not to leave battery-powered devices connected to the mains for any considerable periods of time. Once charged I disconnect them from the mains supply.
Once upon a time the batteries in laptops were NiCad and they were famous for doing just what you described.

I am not saying that the battery should never be used. Once a month or so I do my work while on battery to bring it down to less than 50%. I had a MacBook Air that I used plugged in for just under two years, seldom used the battery and it was at 91% of factory capacity when I sold it.

People can do as they wish as there is not too much you can do to either harm or enhance your batteries in today's modern devices. I seldom own any Apple hardware for over a couple of years so it is really a non issue for me.
 
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Newtons Apple

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Do we have documented proof that this is indeed what happens? Has anyone checked their battery cycle count and then left their iDevice connected to the mains for a couple of days (whilst using it too) before checking the number of cycles again?
No, but common sense would indicate that if you had two iPhones sitting next to each other and one was plugged in all day while the other was unplugged for 12 hours a day before charging, the unplugged phone would have MORE cycles accumulated after a week. Would you not agree to that?

If that is so and there is a limited number of charge cycles on a set of batteries before they needed to be replaced . . . . .
 

sunking101

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No, but common sense would indicate that if you had two iPhones sitting next to each other and one was plugged in all day while the other was unplugged for 12 hours a day before charging, the unplugged phone would have MORE cycles accumulated after a week. Would you not agree to that?

If that is so and there is a limited number of charge cycles on a set of batteries before they needed to be replaced . . . . .
I meant would the plugged in battery show any charge cycles at all?
 

lordofthereef

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Nov 29, 2011
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People are complicating this way too much be it in their heads, on paper, or both. Leaving the cable plugged in has a net effect of nothing on your battery life. The battery is discharged in use and recharged while plugged in. Though you may not see a quantifiable percentage change, the battery is constantly discharging and recharging. Once you have used a sum of 100% of the battery, this counts as one charge cycle.

Your usage patterns will have infinitely more effect on the longevity of your phones battery two years down the road than your charging patterns would. A person who uses their phone all day, even while on the charger is going to put much more "wear and tear" on their battery than a person who uses their phone sparingly off the charger.
 

lordofthereef

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I wonder that too. Not so sure the battery could count 100 small steps into being a full cycle.
Macbook batteries work this way. My macbook is plugged in 99% of the time and it now has a couple hundred charge cycles on it (it has seen maybe a dozen charge cycles off power if I had to guess). I don't see why an iPhone should be any different.
 

Newtons Apple

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Macbook batteries work this way. My macbook is plugged in 99% of the time and it now has a couple hundred charge cycles on it (it has seen maybe a dozen charge cycles off power if I had to guess). I don't see why an iPhone should be any different.

I remember my MacBook Air 13, after near two years of use while mostly plugged in, only showed like 15 cycles . . . go figure.
 
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