USB Charging of iPad

[dgm]

I've got a 2011 car with the comms pack including the USB connector.  This works flawlessly with an iPhone 6 and charges the phone whilst in use.  When an iPad Air is connected, everything works as it should but the iPad doesn't charge.

I've definitely ruled out a cable issue, can anyone suggest why the charging works with the iPhone but not the iPad?

[Horizon]

I've got the genuine usb/ charger lead that came with my IPhone 5S which charges my phone perfectly, but it won't charge my IPad 4. I also have a couple non genuine ones that will work on the phone and the Ipad.
Why the genuine one won't work on the IPad is bizarre 

[dgm]

Bizarre indeed, I've tried two genuine Apple leads and two Kanex leads that I've just bought from Costco, same result with all of them.

[X5Sport]

It may be to do with the USB charging voltage.  My iPad Air will charge on either an iPad or iPhone charger,  but not when connected to a PC USB port nor in the car.

The only thing I can put it down to is the charging voltage available to the USB port, or even a current limiter on both my PC and car.

[dgm]

I think you're correct, did a bit of reading into it and that's all I could find.  Disappointing but at least the phone charges.

[squeaky2]

ipad needs a higher amperage than a iphone.  Probably only half to 1 amp on the usb in the car

[dgm]

Yes, I've bought USB travel adaptors and Scosche car chargers with 2.4amp USB in the past to deal with the slow rate of charging of the iPad but I didn't think the car USB would provide no charge at all which it apparently does.  Looks like I'll just have to live with it, it would've been good to have the iPad playing movie sound through the cars speakers via USB whilst still charging.  It works through Bluetooth so that's the way forward.

[The Mechanic]

It is definitely to do with the charging current that can be drawn.  The standard iphone charger only allows a 1 amp current;  The charger that comes with the ipad is 2.5 amp.  Almost all USB outlets will only allow a current of 1 amp to be drawn, hence the lack of charging of ipad.  I have exactly the same problem with my ipad air.

[touring]

I charged the Ipad via a USB adapter in the lighter socket, so you could charge your phone and pad at the same time.

[dgm]

Yeah, no problems with that, I use the Scosche Revolt charger.  It was really the use of the iPad via USB whilst still charging that was bothering me.