I charged the battery on my 760i from empty to full in less than 2 hours. The charging monitor reported charging currents between 30 and 80mA, which means that there could not possibly be more than 160mAh (2h * 80mA) in the battery. According to the sticker on the battery it should hold a charge of 930mAh.
Realisticly the charging current should be 10x the reported value. Is the error in the calculation on MyPhoneExplorer or in the data provided from the phone? I do not believe that the capacity of the battery has dropped down to 160mAh or below, since the phone is brand new.