How can I diagnose an iPad that seems super slow to recharge?

I've had my iPad 1 for almost a year now. For the past few months it has been charging EXTREMELY slowly.

Last night I plugged it in with 54% remaining on the battery life. This morning it is only at 81%. It charged for 17 hours! Is this normal? The battery seems to last just about as long as it used to (once it's finally charged).

I am using the standard wall charger. I have also tried using my friend's charger and had the same result. Any suggestions?

Be sure you are using an iPad charger. If you are using a standard USB charger or an iPhone/iPod charger then it will take a very long time to charge.

This is normal if the CPU and/or GPU in the iPad is stuck in a loop or legitimately in a loop. You can convince yourself of this by noting the power, plugging it in to a charge and then powering off the device.

Start the iPad up after two or four hours has passed. The battery itself and the charging circuitry run without regards for the OS run state.

Once you've determined if this is the power source (USB with low power) or hardware issue you can get that repaired. If it's just a load issue (too much work to do - draining the charge current for just "keeping the lights on") then you can go down the path to isolate which apps or services are causing your large "touch screen is idle, but the CPU is not" power usage patterns.