[barlala]

Last week I bought a iPad,but I find a problem that it cann't charger on my computer.I plug it on, it shows the state of not chargering.But it can be chargered on the wall plug.Cann't it be charged on computer?Why?

[DINGSTER1]

USB plugs don't draw enough power for that.

[monkeyluis]

If its a Windows PC there was a known issue with being able to charge from those USB inputs, the iPad cannot get enough power from them. If on Mac then it should charge, I'm able too. But I would just use the power adapter it came with.

[camiller]

Computer USB ports typically can supply up to 500mA based on the original USB standard (although some newer motherboards may supply more). The iPad wall adapter (and many third party adapters) can supply up to something like 2.1A or ~4x the amount of power. The higher power outputs are part of the USB Charging standard which only came out within the last few years. For the most part high end tablets and smartphones either will not charge or will charge at a much slower rate on a low power USB port.

[barlala]

Computer USB ports typically can supply up to 500mA based on the original USB standard (although some newer motherboards may supply more). The iPad wall adapter (and many third party adapters) can supply up to something like 2.1A or ~4x the amount of power. The higher power outputs are part of the USB Charging standard which only came out within the last few years. For the most part high end tablets and smartphones either will not charge or will charge at a much slower rate on a low power USB port.

So I should find a USB charger that can charger my iPad and its output is big enough?

[sunjatan]

Actually,iPad can charge on Apple mac computer.In theory,your computer can charge your iPad,but the output current of ordinary computer is lower than iPad,we usually have ordianry conputer such as sony,HP,Dell.These computer's output current is about 500 mAh.So it must take a long time to charge your iPad,iPad2 battery capacity is about 6000mAh,so it many need 12 hours to charge fully,while iPad need 1A output current to charge normally,otherwise itS current is too small,so you cann't see and your iPad will show the status of not charging,actually,it is charging.But need long long
time.
To solve this problem,you can plug your iPad on the wall to charge,but it's unconvenient for you to play iPad.Because you need to find wall plug.Now,there is another way to solve this problem.That is iPad USB charger--can charge your ipad on any computer,and the output current is 1A,can reduce the charge time for half.As far as I know,at present,there are several manufacturers that produce such product,so many people don't know about this product.They endure long waiting for charging your iPad fully.I have found it on amazon for you.
1.XMultiple iPad USB charging Adapter
This brand is the cheapest,but its customer review is not good and customers appraise the quality is not good.
2.BoxWave iPad Charging Adapter, Allows You To Charge Your iPad 3/iPad 2/iPad on ANY Computer or USB Hub for Compatibility With Generic Chargers
The price of this brand is higher than XMultiple,but its product review is good than XM.But still there is a problem that it cann't switch between charge
and sync modes without unplugging the adapter when you wanna sync,so you need to unplug it before switch modes.
3.RAVPower RP-UA01 iPad USB Charging & Sync Adapter - Allows you to charge your iPad iPad 2 the new iPad with any computer or USB Hub
Though its price is a little higher,but it has its own advantages.Its fuctions is similar with Boxwave,but it has a feature that other brands don't have--it can allow you to switch between charge and sync modes without unplugging the adapter when you wanna sync Its design is very compact and easy for carrying.


So only you choose a right USB charger,then you can charge your iPad on any computer and you don't need to worry about this problem.I think many iPad users have met this problem.I hope my explanation can help others iPad users.

[Lunar]

So I should find a USB charger that can charger my iPad and its output is big enough?

Essentially yes. I'm not 100% sure, but I believe the iPad requires a 5V 2A output charger. Find that and you should be golden. As many others have said in this thread, most computer USB ports do not provide near enough amperage to charge an iPad, or most tablets for that matter.

[edenbisdee7215]

Mostly when you plug your iPad into your computer it does not charge your iPad because mostly USB port of your computer doesn't have enough power to charge an iPad. Typically the iPad can only be the charge with an adapter not with computers. Some time your USB port of the computer not working well.