stranton

Hi all first post i'm on here for my mother who has a 2002 540i, now don't get me wrong i drive an Astra and can pull that engine apart all day but this is not as Astra lol. Her car battery is dis-charging and when i tried to turn it over the starter was just ticking, battery was reading 11.2 v so low, jumped the car and it started fine, alternator was showing 13.6-8 v, my Astra shows 14.6 and my dad's Supra 14.7, am I correct in assuming that this is a little low? is there another fault that this car suffer from? Any help would be appreciated Cheers all Stranton