Charging the ipad takes 4,5 hours?

Maybe. How are you charging it? Via the supplied charger? via USB on a new Mac? via USB on another computer? via an iPd/phone charger?

2 1/2 hours with the supplied charger may be a little long. The charger puts out 10 watts. The iPad battery is 25 watt -hours. So ideally it will take 2 1/2 hours for a full charge. However. the charging circuit is not 100% efficient so it will take longer than 2 1/2 hours.

The charging circuits ramp down at different levels so you can not just use the wattage of the power adapter. Plus we don't know if the Ipad was offline or being used.

AND there are protection circuits to keep the heat low which may lower the current and charge time.

When using the Ipad I get 0.56 to 0.82 amp going into the Ipad when the batteries are at 100 percent.

The battery does say 2.48 watt-hr on the ifixit take-apart but there are two of them.

BOb said: "The battery does say 2.48 watt-hr on the ifixit take-apart but there are two of them.".

Where did you get that info? the following ifxit site says:

http://www.ifixit.com/Teardown/iPad-Wi-Fi-Teardown/2183/2

The 3.75V, 24.8 watt-hour battery provides the juice for an advertised 10 hours of use. In contrast, the iPhone 3GS has a 4.51 watt-hour battery and the MacBook Air has a 40 watt-hour battery.

Yes you are right.
There are 2 cell that make up the power unit - most think the cells are connected in parallel.

I guess the only label we see is for the total battery unit and not just one cell .

I wonder what is under the other white material in the picture.