Where is the battery on my Aprilia Habana Custom 125?

Where is the battery on my Aprilia Habana Custom 125? The bike has been unused for about 4 years and there is no discernible charge. The manual does not seem to deal with this for the 125cc model, only the 50cc, which appears to be different. If the battery is that old, will it need replacing, or could I get a charger and charge it up while it is still in the bike?

Al G
April 2010