Hey,
In case you wanted to closely monitor the battery (cycle count, actual charge status, etc.) you might want to download an app such as cocnutBattery. First, once you have charged plug the device in and the app will tell you exactly where you are in the charging department, so to speak. Based on that you could estimate the total time until the device is fully charged. On a side note, the battery is indeed huge - 10,000 mAh.
Cheers.