如果您拥有 iPhone、iPad 或 iPod(iPad or iPod)，您可能已经注意到它的充电方式有些奇怪：快到一定百分比，然后随着接近 100% 越来越慢。几周前我注意到了这一点，由于我对电流、电力、电压、安培、充电器等几乎一无所知，我不确定这是否是我的 iPhone 应该充电的方式。
最终，我也在 iPad 上对其进行了测试，并意识到它做了同样的事情。% pretty fast充电到 70-80% 左右，然后在达到 100% 之前会显着减慢。实际上，根据我的计算，从 1% 到 80% 所需的时间与从 80% 到 100% 所需的时间大致相同！
在这篇文章中，我将解释我对苹果(Apple)产品充电所学到和理解的一点点，希望能让你对到底发生了什么有所了解。如果您是工程师或(engineer or someone)对此主题非常了解的人，请随时在评论中发表您的想法！
电源与充电器
首先要了解的是电源(power source)和充电器之间的区别。在您拥有任何Apple 设备(Apple device)时，您可能在一生中至少说过一次以下声明：“我的充电器在哪里？” ( “Where’s my charger?” )
不幸的是，这种说法在技术上是不准确的。插入墙上的电缆和适配器实际上只是一个(cable and adapter)电源(power source)。它从您的墙上(wall and delivers)汲取电流，并为您的 iPhone、 iPad 或 iPod(iPad or iPod)提供一定数量的(set amount)安培和瓦特。充电器(charger)实际上在设备本身中。这就是为什么您可以使用iPhone 充电器(iPhone charger)为 iPad 充电或使用 iPad 充电器为 iPhone 充电的原因。
iPhone 或 iPad(iPhone or iPad)内部的充电器控制电流流入设备，而不是适配器。如果您检查过，iPhone 适配器(iPhone adapter)的额定功率为 5 瓦和 1 安培。iPad 适配器的额定功率为 10 瓦和 2.1 安。
iPhone 和 iPad 充电器
iPad 或 iPhone(iPad or iPhone)内的电池是可充电锂离子聚合物电池(lithium-ion polymer battery)。这是Apple用于其所有设备（包括Mac计算机）的内容。苹果(Apple)有一个很棒的页面解释了他们的电池技术(their battery technology)，但最好的部分是他们提供的这张图表：
让我们看一下这张图表。在Y 轴上(Y axis)，我们有电流电压(Voltage)(A/V)。A 代表安培，V 代表伏特。第一个数字是安培，第二个是伏特。在X 轴上(X axis)，我们有充电阶段：快速充电和涓流充电。第 2 阶段(Stage 2)解释了为什么您的Apple 设备(Apple device)在电量超过 80% 时会变慢并需要更多时间充电。
如您所见，安培数在前两个小时保持为 1（iPhone 为 2.1，iPad 为 2.1），然后在接下来的两个小时内一直下降到设备充满电后的零。您可能还注意到，有时当您断开iPhone 或 iPad(iPhone or iPad)与充电器的连接时，电量可能在 96% 到 100% 之间。这是因为涓流充电。当它达到 100% 时，它会关闭。如果电池开始下降，它将恢复到大约 96 % and start再次开始缓慢充电。
为什么我们需要涓流充电？
所以这就带来了一个问题：为什么我们需要涓流充电？为什么不直接快速充电到 100% 并完成它呢？好吧(Well)，显然它与锂离子电池背后的化学成分有关，我对此一无所知。简而言之，锂离子电池对过度充电的反应非常糟糕，因此您永远不希望这种情况发生。
涓流(Trickle)充电通过在充电后期减少电流并在电池充满电后完全停止来解决这个问题。这就是为什么即使在充满电后将设备连接到电源(power source)也无害的原因。
总之，充电器在您的设备内部，而您插入墙上的东西是电源适配器(power adapter)，而不是充电器！所有这些技术基本上可以在许多充电周期内保持您的电池寿命。(battery life)如果您有任何问题，请在评论中告诉我们！享受！
OTT Explains – Why Your iPhone Charges Fast First and Then Slows Down
If you own an iPhone, іРad or iPod, you maу have noticed something a little odd about thе way it chargeѕ: fast up to a certain percеntage and then slower and slower as іt gets closer to 100%. I notіced this a few weeks back and sinсe I know practically nothing about current, eleсtricity, volts, ampѕ, сhargers, etc, I wasn’t sure if this was the way my iPhone was supposed to charge оr not.
Eventually, I tested it out on the iPad too and realized that it did the same thing. It would charge to around 70-80% pretty fast and then would slow down significantly before getting to 100%. Actually, from my calculations, the time it took to go from 1% to 80% was about the same time it took to go from 80% to 100%!
In this article, I’ll explain the little I learned and understood about charging Apple products and hopefully will give you a bit of an understanding of what exactly is going. If you are an engineer or someone who knows a lot about this topic, feel free to post your thoughts in the comments!
Power Sources vs Chargers
The first thing to understand is the difference between a power source and a charger. You probably have said the statement below at least once in your life in you own any Apple device: “Where’s my charger?”
Unfortunately, this statement is technically inaccurate. The cable and adapter that you plug into the wall is actually just a power source. It draws current from your wall and delivers a set amount of amps and watts to your iPhone, iPad or iPod. The charger is actually in the device itself. That is why you can use an iPhone charger to charge an iPad or an iPad charger to charge an iPhone.
The charger inside the iPhone or iPad controls the flow of current into the device, not the adapter. If you ever have checked, the iPhone adapter is rated at 5 watts and 1 amp. The iPad adapter is rated at 10 watts and 2.1 amps.
The iPhone and iPad Charger
The battery inside your iPad or iPhone is a rechargeable lithium-ion polymer battery. It’s what Apple uses for all their devices, including Mac computers. Apple has a great page that explains a bit about their battery technology, but the best part is this chart they provide:
Let’s take a look at this chart. On the Y axis we have Current Voltage (A/V). A is for amps and V is for volts. The first number is amps and the second one is volts. On the X axis we have the stages of charging: fast charge and trickle charge. Stage 2 is what explains why your Apple device slows down and takes more time to charge when you get past 80%.
As you can see, the number of amps remains at 1 (for the iPhone, 2.1 for the iPad) for the first two hours and then drops off over the next two hours all the way down to zero when the device is fully charged. You have probably also noticed that sometimes when you disconnect your iPhone or iPad from the charger, it could be anywhere from 96% to 100%. This is because of the trickle charging. When it reaches 100%, it shuts off. If the battery starts to drop, it will kick back in around 96% and start charging again slowly.
Why Do We Need Trickle Charging?
So this bears the question: why the heck do we need trickle charging? Why not just fast charge all the way to 100% and be done with it? Well, apparently it has to do with the chemistry behind lithium ion batteries, which I have no idea about. In a nutshell, lithium ion batteries react very badly to being over-charged and therefore you never want that to happen.
Trickle charging solves this problem by reducing the current at the latter part of the charging and completely stopping it once the battery is fully charged. That is why it is also not harmful to leave your device connected to a power source even after it has fully charged.
In conclusion, the charger is inside your device and the thing you plug into the wall is the power adapter, not the charger! All this technology is there to basically preserve your battery life over many charge cycles. If you have any questions, let us know in the comments! Enjoy!
