First charge

It doesn’t matter. Lithium ion batteries are not picky about the first charge. You should try to leave it plugged in while first setting it up, because the setup process can use a lot of energy, but there is no need to charge it before setup if it is over 50%.

Charge it overnight. During the day just charge enough to get through the day. But don’t obsess over it. There is very little you can do to damage the phone or that will have that much affect on longevity. The battery will last until you are ready for a new phone most likely, and if it doesn’t it will only cost $69 to replace the battery at an Apple store, usually while you wait. You should also consider AppleCare+, which will cover free battery replacement for two years, as well as screen replacement for $29 and even phone replacement if damaged for $99. And if you still have the phone after 2 years you can extend AppleCare for a small monthly charge.

The absolute best way to get maximum use on a charge, as well as slow the decline of battery capacity long term is to enable Optimized Battery Charging (Settings/Battery/Battery Health) and charge the device overnight, every night. The battery will fast charge to 80%, then pause. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often. The phone will resume charging to reach 100% when you are ready to use your phone; it will “learn” your usage pattern. If you enable iCloud Backup (Settings/[your name]/iCloud - iCloud Backup) the phone will back up overnight also, assuring that you can never lose more than the current day’s updates.

Lawrence Finch wrote:

While this is an interesting and useful discussion, we should probably take it to the Water Cooler and not clutter up or confuse general users.

Although some of the understanding of the technology is still somewhat in its infancy, there isn't necessarily anything magical about it or so complicated that we can't get a little into the weeds. I personally think we can give some people a little more credit for receiving an explanation of how the technology works, even if that's not at the level of a university/corporate white paper. I personally say don't worry about it and let the battery management handle it rather than losing ones sanity overthinking it. But it's not a bad thing trying to provide a little technical background into why batteries lose capacity. Knowing is one thing. Worrying is another.

There's a lot to digest an a lot of different recommendations out there - even among different companies that pretty much use the same battery technology. Apple doesn't have access to some super duper advanced battery technology that Samsung, LG, etc. don't have, yet they make recommendations that are different, and they program their battery managements systems differently. Those are all just design choices. But a little background and I think most people will figure out enough of this to know if they shouldn't need worry about every little detail.

Well, it’s not good to leave it at 100% for extended periods of time. That’s why Apple implemented optimized charging. It only charges to 80% and stops for most of the night, then goes to 100% in time for when you start using it, so it is only at 100% for a short time. This is what it looks like:

As you can see, it stopped charging at 10:30 PM at 80%, then completed the charge around 7 AM, and it started decreasing around 10 AM. So it was only at 100% for 3 hours.

If you charge overnight it is unlikely you will need to charge during the day. You only need to if it drops below or even close to 20%. There’s nothing magic specifically about 20% either, but if it gets that low and you use a feature that requires a lot of power (such as a long phone call) it could go so low the phone would shut off. You should never intentionally let it get so low it shuts off; that is not good for the battery long term.

If you charge it regularly during the day that confuses the optimized charging. You shouldn’t charge it when you get home unless it is very low (under 30%). Put it on to charge when you are finished with it for the day. Do that for a couple of days and optimized charging will begin to work they way my graph shows. I put it on to charge at bedtime, take it off in the morning. It starts at 100%, and most days does not require further charging until the next evening.

I will charge it in the car if I am using navigation (which is a heavy drain), but I also keep it below 80%. As long as it is below 80% before starting nighttime charging optimized charging will work.

While this is an interesting and useful discussion, we should probably take it to the Water Cooler and not clutter up or confuse general users.

presilaa wrote:

Well, and after all that, which is better - to leave your phone at night for optimal charging with pause and charge of 100% or to put it on during the day when it falls below 20% and remove it when it becomes 80% and never let it charge to 100%?

As Lawrence Finch explained above, best practice is to enable Optimized charging in Settings>Battery>Battery Health>Optimized Battery Charging and then plug the phone in at night before you go to bed. The phone will take care of the rest automatically.

But, perhaps more important, don't overthink this. Batteries are consumables. They will decay and need to be replaced. At best, you can delay the end of life by a short period of time.

presilaa wrote:

That is, when I leave it to be charged to 100% every night with this function for rest, there will be no problem with the battery (because it says that it is not good to charge to 100%)

Batteries never truly charge to "100%". Or at least not with any competently designed lithium-ion battery charging system. The "100%" point is chosen at a lower point than the absolute maximum possible as a safety margin as well as to increase the longevity of the battery. Also - no system is going to continuously charge after it's "fully charged" and connected to power, regardless of what's displayed. It will stop charging and then wait for the charge level to drop to a designated point before it will start charging again. But the key is that it's not really charging once it's "full".

There's one tool available for Macs called Coconut Battery. It will provide a live snapshot of things including charging rate of an iPhone or iPad connected to the Mac. It will indicate "Fully Charged" where there's no charging current. And there are interesting side notes like seeing that it's still considered "Fully Charged" even after the charge level drops a little bit. But that sort of thing is pretty standard with charging systems today. They simply have to stop applying a charging current at a certain point to protect the battery. It's not like older NiMH or NiCad batteries that are theoretically safe (although not currently recommended) to apply a "float charge" once fully charged to keep the charge level from dropping. Those types of batteries were safe to charge up to a maximum charge level. That's not a good idea with Li-ion batteries.

presilaa wrote:

if I understood correctly, keeping the phone charged to 100% at night does not interfere with the battery, during the day it is not good to leave at 100% charge for a long time, but it is better to charge up to 80%.

Depends. Apple's "Optimized charging" was mentioned, although I rarely see it work where it stops it at 80% until the morning. I've seen the notice that it would do that a few times, but most nights my iPhone charges up to "100%" even though I have "Optimized charging" enabled. I usually keep my phone connected during the day and don't worry about it. If it's "fully charged" then "Optimized charging" won't even happen.

Everything done with a rechargeable battery is going to be a compromise between utility and longevity. Every time you charge and discharge the battery, it's going to lose a bit of capacity. It's inevitable, but the question is how much? I've gotten to the point where I don't really care. I figure I'll replace my iPhone often enough that I might need one battery replacement and I'll be on to my next device.

But the one thing I'll say again is to not worry about an Apple battery ever overcharging, because it simply won't do that. The charging current stops when it reaches the maximum charge. But there are things that can be done to reduce loss of capacity. The biggest problem is heat. Leaving an iPhone in the sun where it will go to emergency shutdown mode is not a good thing, although it's happened to me several times. A lot of what Apple charging systems do is to reduce heat, whether it's reducing the charging current after 70% charge and even lower as it approaches the maximum (I won't say "100%") charge.

I think about all this from a theoretical view. It's fun learning more about how this all works. But in the end I generally just use it whenever I feel like it and charge it when I find a place to charge it. When I've gotten a new Apple device, I like to charge it, but it's not strictly necessary to do so. I ask this question - "Does the battery serve the user, or does the user serve the battery?"

y_p_w wrote:

Depends. Apple's "Optimized charging" was mentioned, although I rarely see it work where it stops it at 80% until the morning. I've seen the notice that it would do that a few times, but most nights my iPhone charges up to "100%" even though I have "Optimized charging" enabled. I usually keep my phone connected during the day and don't worry about it. If it's "fully charged" then "Optimized charging" won't even happen.

Did you see the screen shot I posted with the charging graph? It does that every night.

Lawrence Finch wrote:

Did you see the screen shot I posted with the charging graph? It does that every night.

Saw it. But I don't see that happening with mine every night. If I charge it when I get home, the "learning" doesn't necessarily stop it from charging to 100% in the early evening. I looked at mine and it's plugged in (the cross hatches), not charging (the line at the bottom with the lightning bolt), and at 100% overnight for at least 10 hours. It certainly doesn't treat the 80% threshold as some sort of absolute that it has to achieve. It doesn't allow the battery to drop to 80% while plugged in, even though I know background activity is enough to drain the battery if the charging circuits don't supply active current to the device.

I take out my phone when I need to and charge it whenever I'm at a power source like my car adapter. I even keep a USB power pack in my pocket if I'm going somewhere that I might need my phone for an extended time. But for the most part I don't worry too much about the battery. I use it, connect it to power when I feel like it, and will replace the battery (or device) when needed. Like I said, does the battery serve me, or do I serve the battery? It's just another consumable like vehicle tires.