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## Can use ipad charger to charge iphone?

473783 Views 342 Replies Latest reply: Sep 10, 2013 3:00 PM by ronhenderson2 Branched to a new discussion.
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Sep 5, 2012 9:38 PM (in response to emfung)

Their was another post about this charging issue and I explained it all basic on my educational level with electronics. Their were some people who turned it into and utter and complete joke. 99% had no electronic background but made tons of dumb comments. As the post went on a couple people that were using the iPad charger on their iPhone ruined their iphone battery. Once these people started posting that these people stopped with their stupid replies. the reason volts, watts, and amps are put on chargers are for a reason or else why would they put them on.

I can get really technical with formulas on this but I will go with a very simple one. All Apple chargers are 5 volts. Amps is the amount of current flowing into your device to charge your battery. Watts are easily calculated V x A = W

Example. Charger is 5 volts and is 1 Amp so it has 5 watts (iPhone charger)

Charger is 5 volts and is 2.1 Amp so it is 10 watts (iPad charger)

That one I just rounded up the number like apple did.

Most PC's 5 volts and it is .5 amps so it is 2.5 watts

Slow. Charging your battery is best to get the most out of it but who would want to plug their new iPad into their PC and wait 24 hours for it to charge??? No one, not even me. Despite it saying "not charging" on the screen plug it in your PC overnight and remember what you started off with, turn off the screen, let it go for 4 hours, and YES it will charge at a VERY slow rate. The screen says not charging, but give it a try and you will see that it did charge up but very little.

Has anyone looked up the battery capacity of the new iPad verses the older generations??

iPad 3       11,500 mAh battery 42.5 watts

Pad 2          6,944 mAh battery 25 watts

So with their 5 volt charger 2.1 Amp 10 Watts you are fine because you are not going over the battery specs .Pretty amazing how they achieved that many mAh just by making it slightly thicker. Very technical how it was done but not for this discussion but it is almost double capacity.

Now let's talk iPhone.

IPhone 4S     1,420 mAh battery (1.42 Amps)

5 Volts x 1.42 Amps = 7.1 watts

iPad charger is 5 Volts 2.1 Amps 10 watts. Now you see the problem? Will it work Yes, but you are over charging (forcing to much current) your battery. End result you are decreasing the life of your battery.

Apple says you can use any charger and you can see above a simple formula in simple math. So why would you use a charger that is 2.1 Amps 10 Watts on a battery that is 1.42 Amps = 7.1 watts

Does anyone know what the cost is for Apple to put a new battery in your phone? I am curious on that one and would guess its not cheap.

Their is a formula in simple math. Can you use the ipad charger on your iPhone ? Yes. Will it shorten your battery life using the iPad charger on your iPhone? Yes.

This is the simplest formula broken down into simple math.

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Sep 6, 2012 3:58 AM (in response to merlin1128)

Despite your very long and knowledgeable-sounding reply, you are totally wrong. There is no problem charging an iPhone with a charger than can supply MORE current than the device needs.. Current is supplied on demand (unlike voltage). The iPhone charging circuit takes what it needs, not what is supplied. If your claim were true evey device in your house would burn up, because your incoming powerline can supply 150, 200, or even 300 amps. Your hair dryer only requires 10 amps, so why wouldn't it burst into flame?

Yes, I have degrees in electrical engineering, earned long before you were born.

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Sep 6, 2012 4:01 AM (in response to Lawrence Finch)

+1

• Level 7 (24,050 points)
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Sep 6, 2012 4:26 AM (in response to merlin1128)

Actually, I realize I was a little unfair. Your analysis is correct up to the point where you say "now lets talk iPhone". The problem is you don't understand that current is a measure of the maximum capability of the charger to supply current, not the amount that will be forced on the device.

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Sep 6, 2012 8:29 PM (in response to Lawrence Finch)

Long before I was born? I am 42 and your age is ? Hair dryers? I don't think I ever saw a hair dryer with a lithium ion battery in it. Since we are talking hair dryers why do they sell chargers for cars and ones for motor cycle batteries? Why not just buy one and don't say buy one that does both that has selectable settings. Reason being is if you use a car charger which is 10 amps on a 2 amp motorcycle battery you will cook it and if you ise the motorcyle charger on a car battery it will take forever to charge it  So now you see why they sell car chargers, motorcycle chargers, and ones with variable charging rates. Please explain that one why their is not one charger for all car and motorcycle batteries. Please don't use the excuse they are lead acid, AGM, etc. Since we are on AGM batteries tell me about those as well. What charger do you use. What voltage does a car alternator put out?

Since you have such expertise answer these questions too. What voltage reading will you get on a 220 volt 3 phase piece of equipment coming in from testing supply to supply? What reading will you get testing one supply to ground? Do you need a neutral wire to use this 220 bolt 3 phase piece of equipment ? What size light bulbs do they use for an L train that ONLY has a 600 volt power source coming in?

Here's a test I did with help of a couple co-workers.

Just like the last forum post here we go again. I used an old iPhone and obtained 2 other ones and put brand new batteries in them. Altered the charger to put out more than 2.1 amps and did 50 charge/discharge cycles on one. Did the same with te other one at 1 amp, and the other at .5 amps

After that let all 3 devices sit for 3 days all at the same settings and the one that was charged at .5 Amps had the best battery capacity and the one with the altered charger was the worst? Please explain that and answer my 3 phase power question.

• Level 5 (7,625 points)
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Sep 7, 2012 3:30 AM (in response to merlin1128)

merlin1128 wrote:

... I used an old iPhone and obtained 2 other ones and put brand new batteries in them. Altered the charger to put out more than 2.1 amps and did 50 charge/discharge cycles on one. Did the same with te other one at 1 amp, and the other at .5 amps

After that let all 3 devices sit for 3 days all at the same settings and the one that was charged at .5 Amps had the best battery capacity and the one with the altered charger was the worst? Please explain that ...

"Slow. Charging your battery is best to get the most out of it"

• Level 6 (13,880 points)
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Sep 7, 2012 5:28 AM (in response to emfung)

"why do they sell chargers for cars and ones for motor cycle batteries?"

Because of the current draw difference between a car battery and a motorcycle battery.  Since a car battery charger is more robust, it costs more than a motorcycle battery charger.  Let's consider something easier for you to understand.  If all of Apple's battery chargers have the same voltage output, why doesn't Apple just sell one?  Because the higher wattage power adapter costs more to manufacture than a lower wattage device.  I have 20 years more experience than you do and 16 of those were with Apple.  Ask away; make my Danish.

"What size light bulbs do they use for an L train that ONLY has a 600 volt power source coming in?"

A couple days ago, a guy posted something about a Trifield meter, and asked how to lower the USB voltage to minimize a magnetic field.  It has nothing to do with your post, except my realization than the sale of tin foil hats has increased by one.

• Level 7 (24,050 points)
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Sep 7, 2012 5:55 AM (in response to merlin1128)

merlin1128 wrote:

Long before I was born? I am 42 and your age is ?

Yes. Before you were born. Certainly. In the year you were born I was on the team that deployed the first electronic landing system for aircraft carriers on the USS Kittyhawk. I designed the shipboard component, and a co-worker and friend designed the airborne receiver.

Thee's no point in arguing with you, as your mind is made up. What is wrong with all of your analogies is that the "charger" for iPhones and iPads is not a charger at all. It is a 5 volt DC power source. The charger itself is inside the device. The internal charger regulates the charging current to the battery. For car and motorcycle batteries the charger is external. Thus, the external charger must regulate the charging current to prevent damage to the battery.

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Sep 7, 2012 6:14 PM (in response to Lawrence Finch)

I still do not see all the questions I put up answered. If any of you are really what you say your background is these are a no BRAINER to answer. one is a little technical I will admit.

Bottom line is over charging a battery decreases its life span. I did the test and proved it. Do I care about what any of you claim you know or do? NO.

Still waiting on the questions I asked. If u really had the background most are simple and you should know the answer instantly. Not answering them tells me all the stuff you typed is something made up.

So. Any of you experts gonna answer these simple questions based on your expertise knowledge? People reading this should be wondering if u claim what you say your knowledge is then why are they not answered. I could have got really technical but figured I would keep it simple.

You do not know about 600 volt supplies or 220V 3 phase??? This is simple stuff.

• Level 8 (47,690 points)
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Sep 7, 2012 6:21 PM (in response to merlin1128)

"You do not know about 600 volt supplies or 220V 3 phase??? This is simple stuff."

Simple, yes. But relevant? No. Impressive? No.

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Sep 8, 2012 12:41 AM (in response to merlin1128)

Actually, as someone reading this thread, I was interested in the discussion until you got angry, bro. I'm more inclined to listen to the calm rational people so you are kind of hurting your case by getting all defensive and attacking everybody else. Calm down and explain, man.

• Level 5 (7,625 points)
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Sep 8, 2012 2:08 AM (in response to Zerotogo)

Anybody who refers to "forcing too much current" is perhaps not the place to seek explanation.

The point under discussion is whether or not the iPad "charger" is harmful to lesser devices.  I believe that Apple employ extremely well qualified people who check the facts before Apple puts the following into every Apple Store on the planet. Look up the iPad charger for yourself, and consider which side of the argument carries more authority.:

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Sep 20, 2012 8:00 PM (in response to Lawrence Finch)

As I biomedical engineer, I can affirm that Mr. Finch's analysis is correct.  FWIW, this is a very simple engineering question which doesn't require debate.  I'm very impressed that you were part of the team that designed the first electronic landing system for the USS Kitty Hawk.  That's really cool!

Also, Merlin has confused mAh and watts in describing the capacity of batteries--watts are a unit of power.  One can compare mAh and watt hours.

The essential point that Mr. Finch already explained is that the wall "charger" is just a 5V DC power source, and the iPhone will draw as much current as it is programmed to, and not the maximum output capability of the wall "charger."

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Sep 27, 2012 7:24 PM (in response to merlin1128)

Merlin, you know enough to be dangerous as they say, but not enough to question yourself. Mr. Finch is correct, the iChargers ; ) are just a simple power source. The regulation is done within the device. Now, could there be an issue with the internal regulation design? Maybe, but doubtful. I can tell you there are engineers dedicated to power supply, distribution, and regulation in any decent electronics design company - I know that for a fact from the time you were 10 years old, and these guys weren't brand new at it back then. (and I bet Apple employs some pretty good ones).

Throwing out all that other stuff detracts from your intent, give it up. Mr Finch is also correct about battery chargers for cars versus motorcycles - the regualtion has to be in the charger because it's being directly connected to the battery. That's not the case with an iPhone or iPad.

If you believe your testing has found something, contact Apple - or one of the product review sites, they would be interested in such an issue and could substantiate your finding if it's valid.

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Sep 28, 2012 9:07 AM (in response to merlin1128)

I think we all agree that overcharging a battery or charging a battery too quickly is not good for its lifespan. However, Mr Finch is correct in many points. Who cares how many degrees you have or how old you are. Your qualifications do not matter if you cannot answer the question correctly.

If you had just broadened your scope of the problem you'd realize that it does not make sense for Apple to design intelligent power adapters. The power regulation comes from the device (iPad, iPhone, etc). The reason why the iPad charges slower when on computer power USB is because the regulation circuit is not getting enough current.  However, as Finch said, greater supply current is not a concern.

A better approach to a more valid test is to verify the current being consumed by both the iPhone on the iPhone charger and iPad charger.   If the current is the same then we can conclude that the battery regulation is working the same. If it doesn't, then there may be some validity into different regulation circuit designs.  We also should check voltages and variation or ripple.

Now I am off to do more fun things than typing on this iPad in this form. Whoops I forgot about voice dictation. Looks like I'm the idiot after all.

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