Do I need to charge my iphone more 30 minutes after 100% fully charged?

the information from Apple should come from the engineers who designed the phone.

Anything else is conjecture from people who use the internet and
I'm going with door #1 (Apple). An Apple device showing 100% charge does not need additional time to be "charged" if the device is already reporting it's charge completion.

Again this is what Apple provides as a guide for batteries and again this was likely written from the information provided by the engineers who built the phone, not someone who has provided unsubstantiated technical advice that has not been reviewed by any credible source.

http://www.apple.com/batteries/maximizing-performance/

You are overthinking this. Use your phone, and enjoy.

There is no need to try and micro-manage the process.

Charge at any time for any amount of time.

Use it while it is charging.

It is OK to leave it attached to the charge unit after it reaches 100%.

Read the link (in blue) Jimmy gave carefully above.

All the correct info from Apple is there (it's their product and not Tom, Dick or Harry) and stop believing what the Internet says.

A great many people simply use their phone during the day. At night they plug it in and leave it plugged in until they need to take it with them again the next day. That simple regimen has worked just fine for many iPhone and iPads over the years. There is absolutely no need to monitor or manage the charging of any SMART lithium battery.

Partial charges (and partial discharges) are fine, and once the battery reaches full charge, all charging stops automatically.

Follow Michael Black's advice. Charge the phone overnight. Plug it in when you go to bed. Unplug it when you get up. You get several benefits from this:

• You usually won't have to charge it during the day
• WiFi will stay on, so any background apps will use WiFi instead of cellular data, as WiFi turns off when the phone is asleep and not plugged in
• If you turn on iCloud Backups your phone will automatically back up every day
• There is no downside; it is impossible to overcharge an iPhone, as Michael explained.

Since you are studying electricity, you should be familaiar with the operation of a multimeter. If so, use one to measure the current flow at the start of a charging cycle, continue to observe this current as charging progresses. As the battery charge nears 100%, the current flow becomes less and less. When the battery reaches 100%, current flow stops.

However, since you appear to want to charge it in a way that defies the smart technology built in to modern batteries, go ahead.

ntd252 wrote:

All right thanks for your all suggestions! Maybe I'm thinking about the charging too much. All the worries make me want to understand deeply what charging happens. Also, I'm studying about electricity, so I want to know about it.

About charging overnight or charging too long, I think it can be harmful to the battery.

You think wrongly. The "charger" is not the thingy that plugs into the wall, and the "charger" is not the cable. The charger is an IC in the phone that completely controls charging. When the battery reaches full charge the charging stops COMPLETELY. It does not trickle charge. You can charge it for a week if you want to; when the state of charge drops by about 5% due to apps using energy the charger turns on again to bring it back to full charge. If you are watching the phone carefully all the time you will see this actually happen.

In theory of physics and chemistry, after being fully charged, the charger still has to provide energy to the battery (the charger doesn't switch off completely)

The charger DOES switch off completely.

Since you are studying electricity, go and buy a USB Power Meter, put it in the circuit between the power source and the phone, and monitor the charging current. You will see it drop to zero when the battery reaches full charge. Here are some USB power meters to consider: https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords= usb+power+meter

As Lawrence mentions, charging does indeed stop, truly stop, until the charge state of the battery creeps down below a set threshold.

Most of the "habits" about charging you mention are from people who are simply out of date with the state of modern lithium battery technology. These ingrained ideas about battery use relate to older battery technologies from early laptops and portable devices (e.g. the 1980s in particular when non-luggable, true laptops came into being), such as NiMH (Nickle Metal Hydride batteries, which in turn had replaced dry lead-acid batteries in portable TVs and the like). These battery chemistries were very fickle about partial discharge/charge cycles, did suffer from memory effect and so forth. They also had no or only very simply and limited charge control circuits.

Lithium ion/polymer batteries, if built to the international industry standards (SMART standards) have very sophisticated regulatory circuitry to control both output and charging input to the battery. Those electronic controls are integral to the actually battery itself or to the device which houses the battery in an enclosed device like an iPhone. The electronics control conditions to eliminate over-charging, as well as over-depletion (which is why your iPhone self-powers off when the charge level gets too low, to avoid a damaging over-depletion).

The whole point of Lithium battery technology, and the adoption of those industry standars (aside from making the chemistry safe to actually use), is so consumers do not have to worry about actually managing the state of the battery. They can just use it without having to deal with such issues at all.

That sort of use is fine. You can of course simply charge it more frequently, regardless of how much charge remains, at any time, if you want to make sure it has enough charge for when you do need to use it.

Battery life will decline more rapidly with regular and/or frequent deep discharge cycles, so it is best to make sure the device never runs down so low it auto-powers off. Since partial and frequent charges will do no harm, there is no reason to subject the battery to frequent deep discharges.

But if your use is such you can get a couple or few days between needing to charge that is okay.

As Michael said, yes, that's fine. My wife doesn't use her phone much, and can also go 3 days between charges. But she usually plugs it in every night simply so it is part of her nighttime ritual and she won't forget some day.

You're welcome.