Can use ipad charger to charge iphone?

Wow, what a thread to stumble into.

Couple things:

Lawrence (and Apple depending on how you interpret "compatible") are the only ones that i see have provided data (measurements) to support that the iPad charger is works the same.

Showing charging or battery life difference does NOT prove causality. There's many ways that you can use the phone to kill the battery faster or shorten its usable life. It doesn't mean the charger made the difference.

As far as I know, USB chargers are pretty much all interchangeable (or at least that's how I've used them coming from many android phones). It makes sense that the phones determine the "pull" because they often need to cut down the charging rate to avoid "overcharging" the battery. That was one way I knew of to truly damage my old Epic 4g. You could keep re-plugging it in at 100% to overcharge it for more battery life (killing it in the long run). The fact that the regulation was done in the phone makes sense.

Anyways, jumping into this thread for the first time, I've only seen real data for Lawrence's argument.

I have to admit having just read through this thread, that I too am buying Lawrence's and Lumen's explanations. They fit with my understanding from my engineering degree, although I have to admit as soon as I was able to drop Electrical, I did - but that was after 2 years of degree level study!

I might be hijacking the thread a bit (apologies if so), but I have a very related question and want to exploit the expertise on show in this thread.

I travel a lot and just bought an iPhone 5 in Europe with a European plug for the power charger. I have an old charger with UK plug from my previous Android phone.

Both Apple and Android chargers show the same output performance stats: 5v, 1A (i.e. 5W max output). In a perfect world, they should then be identical. However...

Is there any reason to believe the Android charger could damage my iPhone? Quality of components perhaps?

I'm hoping to avoid giving Apple yet more money for a UK charger...

Thanks,

Martin

Any quality USB charger that can supply a minimum of 0.5 amp should work with the iPhone. I have several aftermarket chargers that I use interchangeably. The industry did something right for once with USB; it's a world-wide standard, and all devices manufactured to meet the standard should be interchangeable.

For what it's worth, I have from day one charged my iPhone 4 with the supplied charger, an iPad charger, a Bose SoundDock, and at least three anonymous USB plugs that cost at the most £1.50 from eBay, sometimes with an included car charger, through a variety of cables from Apple's down to cables at well less than £1.

I have had zero problems with the phone since I bought it.

FYI, did a test with my one week old iPhone 5 trying the stock base and iPad 3 base. They charge at the same rate as expected:

iPhone

7:58 end 96%

6:08 start

iPad

4:45 end 96%

2:56 start

That is one **** of a coincidence if it's charging at a different rate.

You're link might be the answer and would make sense.

Copy/paste...The USB output also has specific resistances connected to the data pins to indicate to the iPhone how much current the charger can supply, through a proprietary Apple protocol. An iPhone displays the message “Charging is not supported with this accessory” if the charger has the wrong resistances here.

What's it said that was interesting is that the iPhone and the charger use the data pins.

The phone can detect what type of charger it is and the changes the way it operates.

.5 v USB charge (eg. Laptop)

5watt charger

10watt charger

So depending on what the phone is plugged in to depends on how the iPhone charges it self.if the phone knows it can draw more current it does thus charging the phone quicker.

Also if its plugged in to a laptop it knows it can only draw a lower current, to avoid damaging the laptop from drawing to high of a current it can supply. So it would be a slower charge rate.

This would be an answer and explain why people are experiencing these problems.

I’m not even an engineer; I start with that, as this thread is full of hate 🙂

I will not go into the technical details and the dilemma of pulling electricity vs. pushing electricity (whether Power is drawn or pushed) and which component is responsible for the regulation, and which side of the equation do push the other “if you know what I mean”, as it was a nightmare for debaters at the college era.

But if the iPad charger will charge the iPhone faster and would kill its battery (1440mAh) in a few weeks, although it was mentioned by Apple as compatible, then I wonder if it would charge “faster” the iPod Nano 7^th generation (220 mAh), or, iPod Nano 6^th generation (105 mAh), or, Shuffle's (51 mAh). And I mean faster like in 5 minutes and kill it in one day by the same analogy! Since all of the above is compatible with the 10W iPad charger and guess what, with the new 12W iPad charger as well.

Please excuse my ignorance, I’m not an Engineer, I am a Physicist!!

As I recently determined by actual measurement (which you as a physicist would appreciate), and reported in this thread, the iPad charger does not charge the iPhone faster than the iPhone charger does.

Actually a question not strictly a reply. I think I have read everything so far. My question: The Battery Monitoring App I use indicates the same time count down while charging with either the iPad or the iPhone charger, or for that matter one of the USB outlets in an RCA device that plugs into a standard 110 home electrical outlet. Is that a reliable measure of the charge rate? And, does the heat being generated come from the battery itself while being charged, or some kind of internal resistance?

You need to read the specs of the power source. The iPhone charger can supply up to 1 amp. The iPad charger can supply 2.1 amps. But the iPhone will only use 1 amp, so the iPad charger will be running at less than its capacity (nothing wrong with that, BTW; the incoming power in your house can supply 200 amps most likely, but you will never consume that much). If the RCA device can also supply 1 amp or more then it will take the same time as the iPhone or iPad charger to charge the phone. Your battery monitoring app confirms this.

Most older computer USB ports can only supply 1/2 amp (0.5 amp), so the phone will take twice as long to charge using a computer USB port. Some newer computers, and most Macs, can supply 1 amp to at least 1 device, so if your computer qualifies then it will charge the phone as fast as the wall charger. With a Mac the first device to "request" more than 0.5 amps will get up to 1 amp; additional devices will be limited to 0.5 amps.

Lawrence, if you don't think the iPad charger chargers the iPhone faster than an iPhone charger.

Then how do you explain the iPhone charging slower via USB connection?

Going back to the URL about the the break down of the charger it shows that the charger indicates to the phone how much current the phone can draw to charge at optimum speeds.

It uses different resistances though the data pins.

Did you check out the charger break down.

Didn't he just explain slower USB charges (0.5 amps)? Also, as was confirmed above using the timed charging device and my own personal test, the iPhone and iPad chargers charge an iPhone (5 in my case) at the same rate.

Thank you Adrift, for answering. rgvspeed, if you go back in the thread I did timed measurements including temperature measurements using a 1 amp and a 2.1 amp power source (both Apple), and it took the same time to charge with both, and the temperature of the phone was about the same with both (measured, not "it felt hotter").

In that message I also explained why some people might see a faster charge with the 2 amp charger, and it wasn't because the phone charged faster, but because there was a battery drain that slowed the charging with the lower capacity power source.

When a device tries to draw more current than what the USB port can supply (which is .5 amps in your case), the supply voltage of the port drops below 5V.

That could be a way how iPhone "knows" that it cannot draw more current.

So, it sounds like if one were to use the 2amp charger on the iphone, while watching a netflix movie, there would be a benefit in that the higher capacity charger could provide more amperage to charge and watch the movie at the same time.