Charging iPad3 with 7w charger - is it possible?

[snowman1235]

Hi,
I'm setting up a new installation in house and would like to have a wall-mounted iPad3 for controlling the smart house installation. They have a very nice USB charger socket in the same design as all the switcher and sockets... However the current that comes out is only 7w and i'm worried it might not be enough for charging the ipad. Any experience with this? I would really like to have this usb socket as it keeps then the same design of all other switches in the house but would like to make sure it will work as it is quite expensive...

Many thanks in advance to anyone who can help me with this!

Cheers!

 

[leelai]

Hi and welcome to the Forum!

Not sure about your question but have a look at this thread. Hope it helps you.
http://www.ipadforums.net/ipad-3-forum/78841-12-28v-charging-ipad3.html

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We also have our own App - It is a very simple app to navigate.
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iPad 2 3G 64gb

 

[snowman1235]

Thanks for reply. ...If I read this properly (and another thread I found on a similar topic about charging by USB directly from laptop) it seems that it would charge, however much slower and possibly not to a full battery?

This would be acceptable, as it will be plugged in most of the time, but it must be charging at least. What are maybe people's experiences with third-party chargers, that are perhaps not 10W but maybe less (like my potential wall charger is 7W)?

 

[AQ_OC]

When I had an iPad 2 I found several chargers on Amazon that claimed to be 10W but were really 5W chargers. They charged the iPad but there were slow, but they could still be used. More importantly, not all 5W chargers would work on the ipad, but those I got of Amazon did. With the iPad 3, which has a much larger battery, using those would drive me nuts because it would take even longer to reach a full charge. So, using a 7W charger is not optimal, but if it s 5V at 1.4A (at least), then it might work, but it also might not. You need to try it before you finalize your build. No one here can know if that charger will really work at all to charge your iPad 3.

So, some 5W chargers charge the iPad 2, but do it slowly. They would take even longer for the iPad 3.

Also, some 5W chargers simply won't work on either iPad, so you need to proceed with caution. Test, test, test. You can't just ask questions. Take it there, hook it up, and see if it charges.

 

[janner43]

I've been wondering why ipad chargers are identified as 10w when I have always been taught (by IT managers, mainly) to check the voltage & amperage of any charging device before using.

My understanding has always been this.

# The new ipad requires "10w" - which should mean any USB socketed charger outputting 5v & 2amps should be fine
# The issue here is not amperage as the ipad will charge slowly from a PC USB port - 5v & .5amps (2.5w). The thing to be careful of is voltage.
# Amps are "drawn" so if the maximum the ipad circuitry requires is 2.1amps, then even a 5v & 4amp charger won't be a problem as the iPad will only draw 2.1a
# Voltage higher than 5v will likely damage your ipad so if the charger you are thinking of is 5v & 1.4amps, ie 7w, it won't damage your ipad but it may not charge it either. There is a possibility that the ipad attempting to draw a higher current than the charger is capable of delivering may damage the charger, but not the other way around.

Hope that is clear & helps

 

[AQ_OC]

I've been wondering why ipad chargers are identified as 10w when I have always been taught (by IT managers, mainly) to check the voltage & amperage of any charging device before using.

My understanding has always been this.

# The new ipad requires "10w" - which should mean any USB socketed charger outputting 5v & 2amps should be fine
# The issue here is not amperage as the ipad will charge slowly from a PC USB port - 5v & .5amps (2.5w). The thing to be careful of is voltage.
# Amps are "drawn" so if the maximum the ipad circuitry requires is 2.1amps, then even a 5v & 4amp charger won't be a problem as the iPad will only draw 2.1a
# Voltage higher than 5v will likely damage your ipad so if the charger you are thinking of is 5v & 1.4amps, ie 7w, it won't damage your ipad but it may not charge it either. There is a possibility that the ipad attempting to draw a higher current than the charger is capable of delivering may damage the charger, but not the other way around.

Hope that is clear & helps

Voltage is an issue but most USB chargers (not talking about a PC port) do use 5V. However, some of them don't have the correct leads connected on the plug to enable the iPad to charge, even when it provides 5V and 1A of current (5W charger).

 

[janner43]

Voltage is an issue but most USB chargers (not talking about a PC port) do use 5V. However, some of them don't have the correct leads connected on the plug to enable the iPad to charge, even when it provides 5V and 1A of current (5W charger).

I understand what you are saying, but how can it be the case that the iPad cable will charge from a standard USB 2.0 pc/mac port if it (the cable)is not wired correctly as per USB 2.0 standards? Surely if a charger has a USB 2.0 compliant socket, the iPad will charge.

 

[AQ_OC]

I understand what you are saying, but how can it be the case that the iPad cable will charge from a standard USB 2.0 pc/mac port if it (the cable)is not wired correctly as per USB 2.0 standards? Surely if a charger has a USB 2.0 compliant socket, the iPad will charge.

I have seen it in action. Some USB 5V/5W chargers won't charge the iPad and others will. Not all of the lines are needed for a charger because no data will be moved over the connection, but one still must use a USB plug. Physically, a plug is just a plug, but electrically it is different because not all of the connections are used. I believe the iPad, and other devices, like the kindle, look for certain electrical characteristics on the line before they allow charging. It is not just a matter of current and voltage.

 

[janner43]

If have seen it in action. Some USB 5V/5W chargers won't charge the iPad and others will. Not all of the lines are needed for a charger because no data will be moved over the connection, but one still must use a USB plug. Physically, a plug is just a plug, but electrically it is different because not all of the connections are used. I believe the iPad, and other devices, like the kindle, look for certain electrical characteristics on the line before they allow charging. It is not just a matter of current and voltage.

Again, I do understand & I don't wish to appear argumentative , but are we sure that this is due to the cable connections rather than poor chargers?

 

[AQ_OC]

Again, I do understand & I don't wish to appear argumentative , but are we sure that this is due to the cable connections rather than poor chargers?

I don't think it has anything to do with the charger being poor, just what it was designed for. The cable connections only work how they work, but if a charger wasn't designed to charge an iPad they one is left the the option of finding one that will.

One perfect example is the charger that comes with the google nexus 7. It is a 10W charger rated at 5V @ 2A but it won't charge my iPad. But my iPad charger will charge it!

 

[janner43]

The USB 2.0 specs are (pinout wise)...
Universal Serial Bus - Wikipedia, the free encyclopedia
Or
USB pinout and wiring @ pinouts.ru

The 30 pin connector would appear to be like this
Apple iPod, iPad and iPhone dock - AllPinouts

So unless the USB end of the apple charging/data cable isn't USB 2.0 compliant (which surely it is) the only thing to ensure is that the non-apple charger is wired to USB 2.0 standard.

 

[janner43]

I think it turns out that neither of us was completely correct

Here... How USB charging works, or how to avoid blowing up your smartphone | ExtremeTech - in a comment, is the following...

The Nook Color's power brick shorts the data pins, which is something the Nook looks for. As noted elsewhere, that's within USB spec; the Nook is just unusually picky in ONLY charging from something that shorts the data lines. Many other chargers put resistors on them instead, to make them communicate properly with various iDevices (again, as noted elsewhere.) The PS Vita is another gadget that does the same thing. A Vita and Nook Color can use each other's chargers, since they're both looking for that data short, but not most other non-computer chargers.

This now makes sense of what I read here, when it says - Apple iPod, iPad and iPhone dock - AllPinouts

Pins 25 and 27 may be used in different manner. To force the iPod 5G to charge in any case, when 'USB Power 5 VDC' (pin 23) is fed,
25 must be connected to 5V through a 10KOhm resistor, and 27 must be connected to the Ground (for example: pin 1) with a 10KOhm resistor.

So, my conclusion is that the ipad will only charge from a charger that has the data pins (2&3) connected within the charger to the correct resistors. After that the charger needs to be 5v / 2amp. Or to put it succinctly, the charger must say that it will charge iDevices. The voltage & amperage can be checked with a multi meter after that to confirm whether they are outputting 1a (5w) or 2a (10w)

 

[janner43]

IOne perfect example is the charger that comes with the google nexus 7. It is a 10W charger rated at 5V @ 2A but it won't charge my iPad. But my iPad charger will charge it!

Can you say that here

I have an Asus Transformer tf101 but am seriously (like 99%) considering changing to the new iPad. We have a 7" Android tablet for my wife, but I'm thinking that having both types in the family will be the best of both worlds

How do you rate the Nexus? And how much difference is there between the two OSs & apps in your opinion?

 

[AQ_OC]

I think it turns out that neither of us was completely correct

Here... How USB charging works, or how to avoid blowing up your smartphone | ExtremeTech - in a comment, is the following...



This now makes sense of what I read here, when it says - Apple iPod, iPad and iPhone dock - AllPinouts



So, my conclusion is that the ipad will only charge from a charger that has the data pins (2&3) connected within the charger to the correct resistors. After that the charger needs to be 5v / 2amp. Or to put it succinctly, the charger must say that it will charge iDevices. The voltage & amperage can be checked with a multi meter after that to confirm whether they are outputting 1a (5w) or 2a (10w)

These connections are what I mean when I was speaking of the electrical characteristics. Those connections are not evident externally at the plug level and you cannot seem them by inspection of the charger or the cable. Yet, you use a usb compatible charger (USB plug, 5V). The iPad is looking for certain characteristics and if it doesn' find them it won't charge. It has nothing to do with the charger being poor, it has to do with what the designer intended.

You're going to have a hard time measuring amperes on these chargers and cables. The simple way to measure is to use a Kill A Watt meter and plug your charger into it. It will tell you the wattage being drawn by the charger. During the full charge mode, it will clearly show 10W for an iPad, though this will drop as the device nears a complete charge.

The iPad can be charged by some chargers that output 5V @ 1A or even less. But the charging will be slower. When you buy a charger, you need to ensure 5V @ 2A if you want the full rate of charging and it does need to state that it is designed for iPad. Lots of chargers are sold for iDevices that only output 5V @ 1A (I have tested these with a Kill A Watt meter and they only deliver 5W). This issue is widespread and many have had problems with it.

 

[AQ_OC]

Can you say that here

I have an Asus Transformer tf101 but am seriously (like 99%) considering changing to the new iPad. We have a 7" Android tablet for my wife, but I'm thinking that having both types in the family will be the best of both worlds

How do you rate the Nexus? And how much difference is there between the two OSs & apps in your opinion?

I have 3 Android tablets. I like the Google Nexus 7 a lot. It is light, has a nice screen, and has Jelly Bean. I find the apple system greatly superior, overall, but the Androids are improving. Both tabs OS are easy to work with, though I'd say Android requires more fiddling, but it is much more configurable. IMO, Android 4.1 (Jelly Bean) is much better than ICS Android 4.0. The Google Nexus is a sweet little machine. Apple will have to respond to it or it will lose the 7-inch market to Google. I find the tablets apps are simply better on iOS as are the accessories. But Android does give you much greater flexibility. You can connect a usb hard drive, keyboard, or ps2 controller to it, for example.