Can use ipad charger to charge iphone?

Most new houses in the US have 200 amp service; my older house (220 years old) only has 150 amp service, which is only 33,000 watts. Same issue, howeve.

My iPhone gets hot with the iPhone charger. It doesn't get any hotter with a 10 watt charger (3rd party, not Apple's). And I've been using a 10 watt charger most of the time for 3 phones over 5 years, with no obvious detrimental effects. I don't know why you think a 5W charger delivers 4.5 VDC; mine measures at 5 volts. And it doesn't matter, because the charger is in the phone, not in the thing you plug into the wall. The thing that plugs in the wall is a 5 VDC power source (actually, by the USB spec, 4.5 to 5.5 V), not a charger. You could use a 1,000 watt 5V charger and it wouldn't make any difference.

But the best argument is deggie's - If the iPad charger could damage an iPhone Apple's lawyers would never have let the web site list the iPhone as being compatible with it.

Lawrence Finch wrote:

Most new houses in the US have 200 amp service; my older house (220 years old) only has 150 amp service, which is only 33,000 watts. Same issue, howeve.

My iPhone gets hot with the iPhone charger. It doesn't get any hotter with a 10 watt charger (3rd party, not Apple's). And I've been using a 10 watt charger most of the time for 3 phones over 5 years, with no obvious detrimental effects. I don't know why you think a 5W charger delivers 4.5 VDC; mine measures at 5 volts. And it doesn't matter, because the charger is in the phone, not in the thing you plug into the wall. The thing that plugs in the wall is a 5 VDC power source (actually, by the USB spec, 4.5 to 5.5 V), not a charger. You could use a 1,000 watt 5V charger and it wouldn't make any difference.

But the best argument is deggie's - If the iPad charger could damage an iPhone Apple's lawyers would never have let the web site list the iPhone as being compatible with it.

I'm not going to argue about the US house electrical specifications, as a live in Europe, but you have 110V?

Which requires twice the amp as 220V for the same amount of wattage.. Really of topic, but I had to ask.

I know this doesen't apply to all iPhones, but many of them get really hot when using the iPad charger, this is a fact I know. The reason however, is unknown, and there may be several causes that generates this symptom.

Let me explain you about the "chargers"; they are switchmode powersupplys with PSFC(Power Supply Feedback Circuit), which make super smooth 5VDC at zero load. But super smooth voltage in this context, means "ripple-smooth", not 5VDC at any load. I'm pretty sure you didn't measure the output of the supply when charging you phone, because the voltage is most likely to drop.

The reason I used 4.5VDC in my example, is because that is the low-voltage threshold of a regular ALC IC, and if the charger should cut the voltage off or it squeezes itself to the maximum. And since the 5W charger is compatible with the iPad, I assume it has a very low threshold, making the charge-voltage close to battery idle-voltage at iPad charge.

First of all, saying something is compatible with something, is a lawyers statement. It's not the most precise statement, and it definitly has some gray areas regarding the technical aspect. Saying something is compatible, means it's capable of something. Is the 10W charger capable of charging a iPhone? Sure! But it's not necessary the ideal charger... Hmm, of course we expect it to be the ideal charger, since it's Apple, but how do we really know?

Second of all, the iPad charger still makes many iPhones really hot, regardless of what Apple says.. There is just too many people experiencing these symptoms. I'm not saying all this just to argue, this is a real problem among many iPhone owners.

EVERYONE!! I am not trying to argue with anyone but I just want you all to know that MERLIN1128 is correct. I just dealt with this personally on 2 iphone and the battery life started to die at 5%, then 10%, then 20%.

So please trust me, this WILL SHORTEN YOUR BATTERY LIFE! However, apple will replace your phone for free if you tell them the battery is not working correctly no questions asked

Hope I helped some people out there :)

Good thing you only chimmed in... In a febble attempt to prove that guy wrong... Now... perhaps that iphone charger is a simple transformer and not a regulated power supply Which many chargers are unregulated, it forcefully applies the charge. In the case of new electronics with self contained batteries, it internal inturrupts the charging circuit from the internal battery..

SO in the event that its unregulated and the device has no way to switch off the incoming current, then yes, it will burn up stuff like he stated! The extra unused engergy gets turned into heat.. The primary in the transformer only knows whats its being asked of by the secondary ... So it will put out what its windings are capable of.. So if it could put out 5 watts, then 5 watts is what its putting out and nothing less. That is where the regulation circuit comes into play.

Hair dryers you used for example are simple devices that pull as much as they can (designed to; based on their winding (or elements). Televisions have transformers and those are ususally regulated inside.

SO that dude you're attempting to totally discredit... Well its a bit rude. He is correct if the charger is unregulated.

ALL regulation is done IN THE PHONE. Charging rate is determined ENTIRELY BY THE CHARGING CURCUIT IN THE PHONE. The iPad charger differs only in that greater current can be drawn by the iPad charger as needed. The iPhone charger in the phone can't use this extra current capacity.

There's no way the iPad charger can charge the phone battery too rapidly or overcharge unless it's grossly defective, in which case it would fry the charging cur hit entirely.

This was exactly my thoughts on the matter, until I read elsewhere that different chargers can have different voltages set on their data lines. This enables attached compatible devices to know what power supply is attached, and its maximum current capability. This in theory could mean that the iPad charger (should I say power supply) would enable the phone to charge at a higher rate.

I didn't have much equipment to hand and didn't have a spare USB connector to hack apart and measure the DC current draw from the chargers. So I measured the AC current draw from the chargers when connected to an iPhone 5. Within 0.2mA both read the same.

iPhone 5 connected to an iPad charger (supplied with 4th Gen iPad) 22.2mA AC when first connected, dropping to 19.2mA when the display turned off. Checked after 10mins with battery at 50% and still reading the same.

When connected to the iPhone charger, as I said above, the readings were within 0.2mA.

This is obviously a very quick and crude test, and I haven't monitored the whole charging cycle but I'm happy to now use either charger for my phone. The resulting DC charging current (using 240V RMS and ignoring the small power supply inefficiency) is 922mA DC, which is well within a 1C charging rate.

Hey guys, it looks like the consensus is that the iphone regulates the charge and it doesnt matter if the charger can provide more power or not. I believe this but at the same time I am confused.

When I use the iPad charger with my iPhone, my phone charges significantly faster and gets hotter as well. How can this be explained? If the iPad charger doesn't allow more current/power through than the iPhone will allow, which should be the power that the iPhone charger gives, how does the iPhone definitely charge more quickly and get hotter?

When I use the iPad charger with my iPhone, my phone charges significantly faster and gets hotter as well.

Hallelujah!

That's all I've been saying from the start 😉

Plus, my charge depletes much quicker when charged with the iPad charger - what about yours?

Yes I have a solution. To all you guys who say that you can't use the iPad charger to charge your iPhone...don't use it!! Use, oh I don't know, your iPhone charger maybe? If you are right and everybody else is wrong, then let them find out the hard way. How about that for a solution? 🙂 Cheers mate!!

I find this interesting:

http://www.idownloadblog.com/2012/05/21/apple-power-adapter-teardown/

Still just a slightly better built power supply, but they try to make it sound smart. With all this tech inside being so important, why didn't apple build a car charger?

I agree with most everyone, the ipad supply should by rights not cause any problem, but it does seem to for some people I know. Must be the 0.1 extra volt in the ipad 5.1V supply that's burning up everyone's phones!

merlin1128,

I am not attacking your point that ipad chargers may do harm.

Sep 5, 2012 9:38 PM:

iPad 3 11,500 mAh battery 42.5 watts

Pad 2 6,944 mAh battery 25 watts

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

5 Volts x 1.42 Amps = 7.1 watts

...

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

Your charger specs/calulations are correct. Your battery specs are not. mAh stands for miliamp hours. 11,500mAh in the ipad3 = 42.5 watt hours, not just watts (also at internal 3.7V btw). In the iPhone4S 1,420mah ≠ 1.42 Amps... 1,420mah = 1.42 Amp hours. 3.7V x 1.42Ah = 5.254Wh

Also you posted this Sep 5, 2012 9:38 PM:

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.

Yet at Sep 6, 2012 8:29 PM, 22 hours and 9 mins later:

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?

So in less than 24hrs you were able to go from not knowing the price of a new iphone battery, to replacing 3 of them yourself, charging them with different chargers, and letting them sit for 3 days to obtain your "results"? Ok sure.

I think everyone is wrong to some degree. I don't think the ipad charger overcharges the iPHone. But there is a good chance it charges it faster. And the faster you charge a battery the worse it is for long term battery life.

Some say the charging is regulated by the device. But I don't think this is an entirely accurate either as some have painted it.

After all Apple makes a more powerful charger for the iPad 3. And this more powerful charger (or power supply) charges the Ipad 3 faster than the included charger. Why is this if the charging is strictly regulated by the device?

It seems that the charging isn't strictly regulated to a certain amperage. But must have some acceptable range at the very least.

This is all easy to test. Charge your iphone with both chargers a few times and make a note of charging times to full from x percentage. See if a pattern develops.

trip1ex wrote:

I think everyone is wrong to some degree. I don't think the ipad charger overcharges the iPHone. But there is a good chance it charges it faster. And the faster you charge a battery the worse it is for long term battery life.

A common misconception. Electric cars (which use the same battery technology as the iPhone) can charge at 120 V, 220 V, or 440 V. A typical electric car charged at 440 V with a high current supply can be completely charged in 20 minutes. Yet it doesn't hurt the battery, which has a 10 year warranty.

Some say the charging is regulated by the device. But I don't think this is an entirely accurate either as some have painted it.

After all Apple makes a more powerful charger for the iPad 3. And this more powerful charger (or power supply) charges the Ipad 3 faster than the included charger. Why is this if the charging is strictly regulated by the device?

Charging is regulated entirely by the device. The iPad 3 power supply can charge faster because it can provide more current than the included charger. The internal charger cannot charge the battery at a higher current than the 5 volt supply can provide.

This is all easy to test. Charge your iphone with both chargers a few times and make a note of charging times to full from x percentage. See if a pattern develops.

Yes, I've done this. I am currently charging my phone with an Apple 10 W charger (5 v, 2.1 amps). It takes the same time to reach full charge (when the starting % is the same, of course) as it does with a 5 W charger that I previously used. I've also measured the temperature of the phone while charging. That is, I MEASURED it using a laser temperature probe, rather than saying "it felt warmer". It stabilized at the same temperature (~85 deg F) regardless of charger.

I can imagine a scenario where the phone will get warmer and appear to charge faster with a higher current charger, but that isn't because the battery is actually charging faster. There are always background processes running in the phone. They are powered by the battery when the phone isn't charging, and by both battery/charger combination when the phone is connected to the charger. If a background process is busy sending or receiving data the additional capacity of a 10 watt charger can power the app while charging the battery at full current. However, a 5 watt charger will be putting current into the battery while the app is taking it out. There's less total power consumption, so the phone won't be as warm. And, as the battery is being drained while charging, it will take longer to charge. There are even scenarios that have been reported in the forum where the battery actually goes down while connected to power (usually to a USB port on a computer, which typically can only supply 2.5 watts).

Afaik not a common misconception that the faster a battery charges the less its lifespan will be.

The difference wouldn't be night and day but measureable and a company could chalk up the difference as acceptable like, for example, 1000 cycles vs 900 cycles. And note there are different battery technologies out there.

And by strictly regulated I mean some of these devices seem to have leeway to accept more charging current (than dictated by the included charger) if it is being provided. Are all iPhones, for example, only able to make use of 1A of charging current? Possible the newest iPhone models can charge faster with a more powerful charger? i say this because Apple made a larger 12W charger for their newest iPads in order to charge them faster even though the first iPad 3's at least came with a 10 W charger.

I'm convinced by Lawrence Finch's and Lumen's latest posts. I'm a EE major who does a lot of electronics DIY work (micro controllers, embedded systems, robots, as well as household repairs), and I trust the measured results from Lawrence and Lumen (in actual current delivered with less than 1% variation between the two chargers, and temperature gained) to believe that: Apple has designed things such that it *should* be totally safe to use an iPad charger to charge an iPhone.

I do see the reasoning in Merlin's points, but I believe that the data has proven that (as Lumen has said) that the charger/current regulator/current limiter is actually built into the iPhone device, and not into the wall adapter. I cannot explain why Merlin's experiments showed greater battery deterioration when using the iPad charger. It must have been chance: perhaps some batteries were worse than others in his test, and his test results happened to reinforce his hypothesis.

I do acknowledge that some people have observed real-world deterioration in their iPhone batteries. However, I am convinced that these issues were due to faulty batteries and/or faulty chargers built into the phone itself. There's no other rational explanation.

Again, I'm convinced.

Another possible explanation of the disparity: maybe it's the charger/current regulator at fault in Merlin's and the other gentleman's experiences and not the batteries. That is, perhaps both Lumen and Lawrence Finch received devices with working chargers/current regulators. Maybe others didn't have faulty batteries, but had faulty chargers/current regulators built into their iPhones. A faulty charger/current regulator could conceivably have this symptom of working fine with iPhone 1A wall adapters, but unable to cope with 2.1A wall adapters. If this is the case, the result would be: battery life would be fine with the 1A adapter, but poor with the 2.1 A adapter.

In any case, it's clear that Apple *designed* their iPhone so that it would behave completely identical with either adapter (or with any other vendor's adapter, for that matter). However, if Merlin and others are indeed seeing battery life degradation when the 2.1A charger is used, it's either:

- a one off coincidence...really attributable to the batteries that Merlin and others used in their tests

- Or, if this behavior is fairly consistent, then perhaps Apple's built-into-the-device charging/current regulating circuit is frequently failing

I'll take my chances and trust Apple's hardware design. I'm going to buy a 2.1A wall adapter (i.e. an iPad charger) to use with my iPhone.... not because I Want to charge my iPhone faster (because it won't), but because I want to be able to occasionally use the same Lightening plug to charge either device at their fastest possible charging rate.