A curious question about my iPad and how slow it is charging

Hi guys,
So I haven't used my iPad in about 1 week, and all that time it has been dead.
However, when I tryed to plug it in to day, it charges just fine, no cable error alert or anything. But it is charging really, really slowly. As I'm typing right now, it's only 5 percent, and I plugged it in about 45 minutes ago.
Could it be because it hasn't been used in a while and it just needs to refresh itself?
Thanks.