[alex jb]

Is this lmore linked to the mAhr rating of the standard battery?

I found the same thing while using tomtom navigator and playing tunes into the hire car I had, battery got very hot and 2 hrs later I unplugged it and the red light came on along with the warning about main battery low, to prevent data loss...
Did the same thing later the same day with my double size battery and it did not loose charge, it gained charge over the 2 hrs.

Maybe it's even the charging circuit, doubt it can be addressed via a software tweak though.