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iOS 18 is now available

merlin1128 recently posted an excellent article about chargers for iPhones and iPads, how they work, and how to use them. His tip is reproduced (with permission) below.

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I just recently got an iPad and have the iPhone 4, iPhone 4S, iTouch, Ipod, basically I have everything Apple makes. I can see that a lot of people are confused about chargers due to them showing watts, volts, & amps and since I have a very extensive background in electronics I will clarify all this in this post.

Chargers:

Source: Voltage, Current, Power

• Older PC USB: 5 volts, 0.5 amps,2.5 Watts
• Newer PC USB: 5 volts, 1.0 amps (some 2 amps), 5 Watts (10 watts)
• iPhone “Cube” Charger: 5 volts, 1.0 amps, 5 Watts
• iPad Charger: 5.1 volts, 2.1 amps, 12 watts
• USB C/PD charger: Multiple voltages, 13 watts and up (no upper limit)
• A USB C/PD charger 20 watts and higher can fast charge an iPhone 11 or later

If you use an iPhone charger it will show the iPad is charging; now look above at the numbers and you see that it is about 1/2 of what the iPad charger is so it will take twice as long to charge up your iPad using an iPhone charger. Below these are totally hypothetical numbers and not realistic and I am using them to keep it simple and understandable.

I hope this clarifies things up for everyone on this because it is all just math with the output because they all produce 5 volts only difference is Amps and Watts and the equations for that is Volts x Amps = Watts. Apple gives you the 2.1 Amp 10 Watt charger so it won't take a day to charge your iPad due to the battery being much bigger.

Most USB Hubs produce the .5 Amps even though they have an external power supply you plug into the wall. Their are some USB Hubs that have usually 1 port that will produce the 10 watts 2.1 amps, but it will just be out of one port on the hub, so if you buy one read the specifications carefully. Car chargers are pretty much the same, so read before you purchase.

Here is the name of a USB Hub that has ONE fast charge port they call it that is the same as the iPad Charger: Symba 7 Port USB 3.0/2.0 Hub with One Fast Charging USB 2.0 Port (SD-HUB20102) if you want to charge fast and sync your iPad on your computer.

If you are looking for a Car Charger that is 2.1 amps just like the Apple Charger I got a Satechi 2412ST and what is really nice about it is that it is pretty much flush when plugged in, meaning you don't have this charger sticking out of your accessory socket it is flush which is really nice if you have a cove that needs to close you can leave this in...

I know this is long, but I hope all this helps and clears things up for everyone and if you buy any USB Hubs or Car Chargers for your iPad read carefully that it produces 2.1 Amps to get the fastest charge or if you don't mind it charging slower (1/2 as fast) you can get a 1.0 Amp one.

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